Alias: When the estimate of an effect also includes the influence of one or more other effects (usually high order interactions) the effects are said to be aliased (see confounding). For example, if the estimate of effect D in a four factor experiment actually estimates (D + ABC), then the main effect D is aliased with the 3-way interaction ABC. Note: This causes no difficulty when the higher order interaction is either non-existent or insignificant.
Analysis of variance (ANOVA): A mathematical process for separating the variability of a group of observations into assignable causes and setting up various significance tests.
Balanced design: An experimental design where all cells (i.e. treatment combinations) have the same number of observations.
Blocking: A schedule for conducting treatment combinations in an experimental study such that any effects on the experimental results due to a known change in raw materials, operators, machines, etc., become concentrated in the levels of the blocking variable. Note: the reason for blocking is to isolate a systematic effect and prevent it from obscuring the main effects. Blocking is achieved by restricting randomization.
Center Points: Points at the center value of all factor ranges.
Coding Factor Levels: Transforming the scale of measurement for a factor so that the high value becomes +1 and the low value becomes -1 (see scaling). After coding all factors in a 2-level full factorial experiment, the design matrix has all orthogonal columns. Coding is a simple linear transformation of the original measurement scale. If the "high" value is Xh and the "low" value is XL (in the original scale), then the scaling transformation takes any original X value and converts it to (X − a)/b, where a = (Xh + XL)/2 and b = (Xh−XL)/2. To go back to the original measurement scale, just take the coded value and multiply it by b and add a or, X = b × (coded value) + a. As an example, if the factor is temperature and the high setting is 65°C and the low setting is 55°C, then a = (65 + 55)/2 = 60 and b = (65 − 55)/2 = 5. The center point (where the coded value is 0) has a temperature of 5(0) + 60 = 60°C.
Comparative design: A design that allows the (typically mean-unbiased) estimation of the difference in factor effects, especially for the difference in treatment effects. The estimation of differences between treatment effects can be made with greater reliability than the estimation of absolute treatment effects.
Confounding: A confounding design is one where some treatment effects (main or interactions) are estimated by the same linear combination of the experimental observations as some blocking effects. In this case, the treatment effect and the blocking effect are said to be confounded. Confounding is also used as a general term to indicate that the value of a main effect estimate comes from both the main effect itself and also contamination or bias from higher order interactions. Note: Confounding designs naturally arise when full factorial designs have to be run in blocks and the block size is smaller than the number of different treatment combinations. They also occur whenever a fractional factorial design is chosen instead of a full factorial design.
Control group: a set of experimental units to which incidental treatments are applied but not main treatments. For example, in applying a herbicide as one treatment, plots receiving that treatment might be driven over by a machine applying the herbicide but treatments not receiving the herbicide would not normally be driven over. The machine traffic is an incidental treatment. If there was a concern that the machine traffic might have an effect on the variable being measured (e.g. death of strawberry plants), then a control treatment would receive the machine traffic but no herbicide. Control groups are a way of eliminating the possibility of incidental treatments being the cause of measured effects. The incidental treatments are controlled for. Compare treatment groups. A treatment that is only the absence of the manipulation being studied is simply one of the treatments and not a control, though it is now common to refer to a non-manipulated treatment as a control.
Crossed factors: See factors below.
Design: A set of experimental runs which allows you to fit a particular model and estimate your desired effects.
Design matrix: A matrix description of an experiment that is useful for constructing and analyzing experiments.
Design of Experiments: A systematic, rigorous approach to engineering problem-solving that applies principles and techniques at the data collection stage so as to ensure the generation of valid, defensible, and supportable engineering conclusions [1]
Design Point: A single combination of settings for the independent variables of an experiment. A Design of Experiments will result in a set of design points, and each design point is designed to be executed one or more times, with the number of iterations based on the required statistical significance for the experiment.
Effect (of a factor): How changing the settings of a factor changes the response. The effect of a single factor is also called a main effect. A treatment effect may be assumed to be the same for each experimental unit, by the assumption of treatment-unit additivity; more generally, the treatment effect may be the average effect. Other effects may be block effects. (For a factor A with two levels, scaled so that low = -1 and high = +1, the effect of A has a mean-unbiased estimator that is evaluated by subtracting the average observed response when A is -1 from the average observed response when A = +1 and dividing the result by 2; division by 2 is needed because the -1 level is 2 scaled units away from the +1 level.)
Error: Unexplained variation in a collection of observations. See Errors and residuals in statistics. Note: experimental designs typically require understanding of both random error and lack of fit error.
Experimental unit: The entity to which a specific treatment combination is applied. For example, an experimental unit can be a
PC board
silicon wafer
tray of components simultaneously treated
individual agricultural plants
plot of land
automotive transmissions
etc.
Factors: Process inputs that an investigator manipulates to cause a corresponding change in the output. Some factors cannot be controlled by the experimenter but may affect the responses. These uncontrolled factors should be measured and used in the data analysis, if their effect is significant. Note: The inputs can be discrete or continuous.
Crossed factors: Two factors are crossed if every level of one occurs with every level of the other in the experiment.
Nested factors: A factor "A" is nested within another factor "B" if the levels or values of "A" are different for every level or value of "B". Note: Nested factors or effects have a hierarchical relationship.
Fixed effect: An effect associated with an input variable that has a limited number of levels or in which only a limited number of levels are of interest to the experimenter.
Interaction: Occurs when the effect of one factor on a response depends on the level of another factor(s).
Lack of fit error: Error that occurs when the analysis omits one or more important terms or factors from the process model. Note: Including replication in a designed experiment allows separation of experimental error into its components: lack of fit and random (pure) error.
Model: Mathematical relationship which relates changes in a given response to changes in one or more factors.
Nested Factors: See factors above.
Orthogonality: Two vectors of the same length are orthogonal if the sum of the products of their corresponding elements is 0. Note: An experimental design is orthogonal if the effects of any factor balance out (sum to zero) across the effects of the other factors.
Paradigm: a model created given the basic design, the hypothesis and the particular conditions for the experiment.
Random effect: An effect associated with input variables chosen at random from a population having a large or infinite number of possible values.
Random error: Error that occurs due to natural variation in the process. Note: Random error is typically assumed to be normally distributed with zero mean and a constant variance. Note: Random error is also called experimental error.
Randomization: A schedule for allocating treatment material and for conducting treatment combinations in a designed experiment such that the conditions in one run neither depend on the conditions of the previous run nor predict the conditions in the subsequent runs. Note: The importance of randomization cannot be over stressed. Randomization is necessary for conclusions drawn from the experiment to be correct, unambiguous and defensible.
Regression discontinuity design: A design in which assignment to a treatment is determined at least partly by the value of an observed covariate lying on either side of a fixed threshold.
Replication: Performing the same treatment combination more than once. Note: Including replication allows an estimate of the random error independent of any lack of fit error.
Resolution: In fractional factorial designs, "resolution" describes the degree to which the estimated main-effects are aliased (or confounded) with estimated higher-order interactions (2-level interactions, 3-level interactions, etc.). In general, the resolution of a design is one more than the smallest order interaction which is aliased with some main effect. If some main effects are confounded with some 2-level interactions, the resolution is 3. Note: Full factorial designs have no confounding and are said to have resolution "infinity". For most practical purposes, a resolution 5 design is excellent and a resolution 4 design may be adequate. Resolution 3 designs are useful as economical screening designs.
Response(s): The output(s) of a process. Sometimes called dependent variable(s).
Response surface: A designed experiment that models the quantitative response, especially for the short-term goal of improving a process and the longer-term goal of finding optimum factor-values. Traditionally, response-surfaces have been modeled with quadratic-polynomials, whose estimation requires that every factor have three levels.
Rotatability: A design is rotatable if the variance of the predicted response at any point x depends only on the distance of x from the design center point. A design with this property can be rotated around its center point without changing the prediction variance at x. Note: Rotatability is a desirable property for response surface designs (i.e. quadratic model designs).
Scaling factor levels: Transforming factor levels so that the high value becomes +1 and the low value becomes -1.
Screening design: A designed experiment that identifies which of many factors have a significant effect on the response. Note: Typically screening designs have more than 5 factors.
Test plan: a written document that gives a specific listing of the test procedures and sequence to be followed.
Treatment: A treatment is a specific combination of factor levels whose effect is to be compared with other treatments.
Treatment combination: The combination of the settings of several factors in a given experimental trial. Also known as a run.
Treatment group: see Control group
Variance components: Partitioning of the overall variation into assignable components.
AC capacitor
A capacitor essentially designed for operation with alternating voltage.[a]
AC conversion factor
For AC conversion, the ratio of the fundamental output power to the fundamental input power.
AC converter
A converter for AC conversion.
AC filter
A filter on the AC side of a converter, designed to reduce the circulation of harmonic currents in the associated system.
AC voltage converter
An AC converter for changing the voltage.
(electronic) AC (power) conversion
Electronic conversion from AC to AC
(electronic) AC/DC (power) conversion
Electronic conversion from AC to DC or vice versa.
AC/DC converter
An electronic converter for rectification or inversion or both.
angle of overlap
The commutation interval expressed in angular measure.
(valve) arm
A part of the circuit of an power converter or switch bounded by any two AC or DC terminals and including one or more simultaneously conducting electronic valve devices connected together and other components if any.
asymmetrical phase control
Phase control with different delay angles in the principal arms of a converter connection or commutating group.
automatic switching on
The property of an equipment having a forced characteristic such that the equipment is switched on automatically.
automatic switching off
The property of an equipment having a forced characteristic such that the equipment is switched off automatically.
auto-sequential commutation
A method of capacitor commutation where the next principal arm to conduct in sequence when turned on connects the capacitor supplying the commutating voltage to the foregoing principal arm.
auxiliary arm
Any valve arm other than a principal arm.[b]
B Edit
basic converter connection
The electrical arrangement of principal arms in a converter.
boost converter
step-up converter
A direct DC converter providing an output voltage which is higher than the input voltage.
boost and buck connection
A series connection of two or more converter connections the direct voltages of which may be added or subtracted depending on the control of the individual connections.
breakdown (of an electronic valve device or of a valve arm)
A failure that permanently deprives an electronic valve device or a valve arm of its property to block voltage.
breakthrough
A failure by which a controllable valve device or an arm consisting of such devices loses its ability to block voltage during the forward blocking interval.
bridge connection
A double-way connection of pairs of arms such that the center terminals are the phase terminals of the AC circuit, and that the outer terminals of like polarity are connected together and are the DC terminals.
buck converter
step-down converter
A direct DC converter providing an output voltage which is lower than the input voltage.
by-pass arm
An auxiliary arm providing a conductive path which allows the current to circulate without an interchange of power between source and load.
C Edit
capacitor commutation
A method of self-commutation in which the commutating voltage is supplied by capacitors included in the commutation circuit.
capacitor element (or element)
An indivisible part of a capacitor consisting of two electrodes separated by a dielectric.
capacitor losses
The active power consumed by a capacitor.[c][d]
capacitor unit (or unit)
An assembly of one or more capacitor elements in the same container with terminals brought out.
capacitor bank
An assembly of two or more capacitor units, electrically connected to each other.
capacitor
A general term used when it is not necessary to state whether reference is made to an element, a unit or a capacitor bank.
capacitor equipment
An assembly of capacitor units and their accessories intended for connection to a network.
circuit angle
In a rectifier connection, the phase angle between the peak of the line to neutral voltage on the AC line side and the simultaneous or next peak of the unsmoothed direct voltage at zero current delay angle.
circuit crest working off-state voltage
The highest instantaneous value of the off-state voltage developed across a controllable valve device or an arm consisting of such devices, excluding all repetitive and non-repetitive transients.
circuit crest working reverse voltage
The highest instantaneous value of the reverse voltage developed across a reverse blocking valve device or an arm consisting of such devices, excluding all repetitive and non-repetitive transient voltages.
circuit non-repetitive peak off-state voltage
The highest instantaneous value of any non-repetitive transient off-state voltage developed across a controllable valve device or an arm consisting of such devices.
circuit non-repetitive peak reverse voltage
The highest instantaneous value of any non-repetitive transient reverse voltage developed across a reverse blocking valve device or an arm consisting of such devices.
circuit repetitive peak off-state voltage
The highest instantaneous value of the off-state voltage developed across a controllable valve device or an arm consisting of such devices, including all repetitive transient voltages but excluding all non-repetitive transient voltages.
circuit repetitive peak reverse voltage
The highest instantaneous value of a reverse voltage developed across a reverse blocking valve device or an arm consisting of such devices, including all repetitive transient voltages but excluding all non-repetitive transient voltages.
circuit reverse blocking interval
The interval during which a reverse blocking valve device or an arm consisting of such devices is in the reverse blocking state.
circuit off-state interval
The interval during which a controllable valve device or an arm consisting of such devices is in the off state.
characteristic (curve) (of a converter)
A curve showing the relationship between the values of the output voltage and the values of the output current.
commutating voltage
The voltage which causes the current to commutate.
commutation
In an power converter the transfer of current from one conducting arm to the next to conduct in sequence, without interruption of the current, both arms conducting simultaneously during a finite time interval.
commutation circuit
The circuit consisting of the commutating arms and the source providing the commutating voltage.
commutating group
A group of principal arms which commutate cyclically among themselves without intermediate commutation of the current to other principal arms.
commutation capacitor
A capacitor included in the commutation circuit to supply commutating voltage.
commutation inductance
The resulting inductance in the commutation circuit.
commutation interval
The time interval in which commutating arms are carrying principal current simultaneously.
commutation failure
A failure to commutate the current from a conducting arm to the succeeding arm.
commutation notch
A periodic voltage transient that may appear in the AC side voltage of a line or machine commutated converter due to the commutation.
commutation number
The number of commutations from one principal arm to another during one elementary period in each commutating group.
commutation reactor
A reactor included in the commutation circuit to increase the commutation inductance.
composite characteristic
A characteristic consisting of parts of the stabilized voltage and stabilized current characteristics.
conducting direction (of an electronic valve device or of a valve arm)
The direction in which an electronic valve device or a valve arm is capable of conducting current.
conduction interval (of a valve arm)
That part of an elementary period in which the valve arm conducts.
conduction ratio
The ratio of the conduction interval to the sum of the conduction interval and the idle interval.
conduction through
In inverter operation, the situation that a valve arm continues conduction at the end of the normal conduction interval or at the end of the hold-off interval.
(electronic) (power) conversion
Change of one or more of the characteristics of an electric power system essentially without appreciable loss of power by means of electronic valve devices.[e]
(electronic) (power) converter
An operative unit for electronic power conversion, comprising one or more electronic valve devices, transformers and filters if necessary and auxiliaries if any.[f]
converter connection
The electrical arrangement of valve arms and other components essential for the function of the main power circuit of a converter.
converter section of a double converter
That part of a double converter in which the main direct current when viewed from the DC terminals always flows in the same direction.
controllable valve device
A valve device the current path of which is bistably controlled in its conducting direction.
constant current power supply
A power supply that stabilizes output current with respect to changes of influence quantities.
constant voltage power supply
A power supply that stabilizes output voltage with respect to changes of influence quantities.
constant voltage or constant current power supply
A stabilized power supply that operates as a constant voltage power supply or constant current power supply depending on load conditions.
constant voltage to constant current crossover
The behavior of a stabilized power supply that automatically converts the mode of operation from voltage stabilization to current stabilization when the output current reaches a preset value, and vice versa.
continuous flow (of direct current)
A flow of direct current which is not periodically interrupted.
conversion factor (in general)
The ratio of the fundamental output power or DC output power to the fundamental input power or DC input power.
container temperature rise (△θcase) (capacitor)
The difference between the temperature of the hottest point of the container and the temperature of the cooling air.
controlled ideal no-load direct voltage
The theoretical no-load direct voltage of an AC/DC converter corresponding to a specified trigger delay angle assuming no threshold voltages of electronic valve devices and no voltage rise at small loads.
controlled conventional no-load direct voltage
The mean value of the direct voltage corresponding to a specified trigger delay angle which would be obtained by extrapolating the direct voltage/current characteristic from the region of continuous flow of direct current to zero current.
conventional no-load direct voltage
The mean value of the direct voltage which would be obtained by extrapolating the direct voltage/current characteristic. from the region of continuous flow of direct current to zero current at zero trigger delay angle, i.e. without phase control.
cooling-air temperature (θamb) (capacitor)
The temperature of the cooling air measured at the hottest position in the bank, under steady-state conditions, midway between two units. If only one unit is involved, it is the temperature measured at a point approximately 0-1 m away from the capacitor container and at two-thirds of the height from its base.
crossover area
With stabilized power supplies, the range of values of the output quantities within which a change of mode of operation occurs, e.g. from constant voltage to constant current.[g][h]
crossover point
With stabilized power supplies a point given by the intersection of the lines representing the nominal values of the two stabilized output quantities, usually the centre of the crossover area.
current delay angle
The time expressed in angular measure by which the starting instant of current conduction is delayed by phase control.
current pulse width (τ) (capacitor)
Wave Forms
1.A. — A Commutative Diagram.
1.B. — Commutating Circuit Example
2. — Surge Wave Form
{\textstyle f_{p}={\frac {1}{t_{p}}}\qquad \tau =\pi {\sqrt {LC}}}{\textstyle f_{p}={\frac {1}{t_{p}}}\qquad \tau =\pi {\sqrt {LC}}}
τ = capacitor current pulse width
tp = system pulse duration
fp = system pulse frequency
Un = peak recurrent voltage
i = peak current
Fig. 1. Wave Forms
The time of current flow during the charging or discharging from one voltage value to another of the capacitor.[i]
current source inverter
current fed inverter
A current stiff inverter.
current stiff AC/DC converter
An electronic AC/DC converter having an essentially smooth current on the DC side provided e.g. by means to reduce the harmonic currents.
cycloconverter
A direct frequency converter.[j][k]
D Edit
DC capacitor
A capacitor essentially designed for operation with direct voltage.[l]
DC converter
A converter for DC conversion.
DC conversion factor
for DC conversion, the ratio of the DC power value on the load side to that on the source side.
(electronic) DC (power) conversion
Electronic conversion from DC to DC
DC filter
A filter on the DC side of a converter, designed to reduce the ripple in the associated system.
DC form factor
The ratio of the rms value to the mean value averaged over a full period of a periodically varying quantity having a non zero DC component.
DC power
The product of the direct voltage and the direct current (mean values).
DC ripple factor
The ratio of half the difference between the maximum and minimum value of a pulsating direct current to the mean, value of this current.[m]
direct AC/DC converter
An electronic AC/DC converter without a DC or AC link.
direct AC converter
An AC converter without a DC link.
direct (power) conversion
Electronic conversion without a DC or AC link.
direct DC converter
DC chopper
A DC converter without an AC link.
direct commutation
A commutation between two principal arms without transfer through any auxiliary arms.
direct inverter
An inverter without a DC link.
direct rectifier
A rectifier without a DC or AC link.
direct voltage regulation
The difference between the conventional no-load direct voltage and the direct voltage at load at the same trigger delay angle excluding the correcting effect of stabilizing means if any.
double converter
A current stiff reversible AC/DC converter with direct current in both directions.
double-way connection (of a converter)
A converter connection such that the current through each of the phase terminals of the AC circuit is bidirectional.
duty cycle (capacitor)
1. continuous duty; Operation time such that a capacitor is at thermal equilibrium for most of the time.
2. intermittent duty ; Discontinuous working or operation with variable loads which should be described in terms of ON/OFF or HIGH/LOW periods with their durations.
E Edit
electronic AC (power) switch
An electronic power switch capable of switching alternating current.
electronic AC power controller
A unit which is able to operate as a controllable direct AC voltage converter as well as an electronic AC switch.
electronic DC (power) switch
An electronic power switch capable of switching direct current.
electronic device
A device the function of which is based on charge carriers moving through a semiconductor, a high vacuum or a gas discharge.
elementary frequency
The reciprocal of the elementary period.
elementary period
The duration of one cycle of the phenomena that are periodically repeated.
electronic power filter
active power filter
A converter for filtering.
electronic (power) switching
Switching an electric power circuit by means of electronic valve devices.
electronic (power) switch
An operative unit for electronic power switching comprising at least one controllable valve device.
electronic valve device
An indivisible electronic device for electronic power conversion or electronic power switching, comprising a single non-controllable or bistably controlled unidirectionally conducting current path.[n][o]
equivalent series resistance of a capacitor
An effective resistance which, if connected in series with an ideal capacitor of capacitance value equal to that of the capacitor in question, would have a power loss equal to the active power dissipated in that capacitor underspecified operating conditions.
external commutation
A commutation where the commutating voltage is supplied by a source outside the converter or electronic switch.
external quenching
A method of quenching in which the quenching results from causes external to the electronic valve device.
F Edit
false firing
The firing of a latching valve device or an arm consisting of such devices at an incorrect instant.
flyback converter
A DC converter where the energy is transferred from the source side to the load side during the idle interval(s) of the controllable principal arm(s) after being stored in an inductance.
firing
The establishment of current in the conducting direction in a latching valve device or an arm consisting of such devices.
firing failure
A failure to achieve conduction in a latching valve device or an arm consisting of such devices during the conduction interval.
forward breakdown
A failure that permanently deprives a controllable valve device or an arm consisting of such devices of its property to block forward voltage.
forward converter
A DC converter where the energy is transferred from the source side to the load side during the conduction interval(s) of the controllable principal arm(s).
four-quadrant converter
An AC/DC or DC converter with two directions of DC power flow, associated with two directions of direct voltage and two directions of direct current.
free-wheeling arm
A by-pass arm containing only non-controllable valve devices.
frequency converter
An AC converter for changing the frequency.[p]
forced characteristic (of a line commutated converter)
A characteristic obtained by additional means, e.g. stabilization, with specified variation limits of influence quantities.
fully controllable connection
A uniform connection with all principal arms controllable.
fundamental factor
The ratio of the rms value of the fundamental component to the rms value of the alternating quantity.
fundamental power
The active power determined by the fundamental components of voltage and current.
H Edit
half-controllable connection
A non-uniform connection with half the number of principal arms controllable.
harmonic content
The quantity obtained by subtracting from an alternating quantity its fundamental component.
(total) harmonic factor
The ratio of the rms value of the harmonic content of an alternating quantity to the r.m.s. value of the quantity.
high vacuum valve device
An electronic valve device in which the degree of vacuum is so high that the effects of ionization are negligible.
hold-off interval
The interval between the instant when the on-state current of a latching valve device has decreased to zero and the instant when the same valve device is subjected to reapplied off-state voltage.
I Edit
indirect AC converter
An AC converter with a DC link.
indirect AC/DC converter
An electronic AC/DC converter with a DC or AC link.
indirect commutation
A series of commutations from one principal arm to another or back to the original one by successive commutations via one or more auxiliary arms.
indirect (power) conversion
Electronic conversion with one or more DC or AC link(s).
indirect current link AC converter
An AC converter with a current stiff DC link .
indirect DC converter
A DC converter with an AC link.
indirect inverter
An inverter with a DC link.
indirect rectifier
A rectifier with a DC or AC link.
indirect voltage link AC converter
An AC converter with a voltage stiff DC link.
inductive direct voltage regulation
The direct voltage regulation due to the commutation inductance(s).
influence quantity
In the field of power electronics any quantity generally external to a power supply which may affect its performance.
inherent delay angle
The current delay angle occurring, even without phase control, caused by multiple overlap.[q]
inherent direct voltage regulation
The direct voltage regulation excluding the effect of the AC system impedance.
intermittent flow (of direct current)
A flow of direct current which is periodically interrupted.
internal discharge device
A device incorporated in the capacitor connecting the terminals of the unit, capable of reducing the residual voltage effectively to zero after the capacitor has been disconnected from the supply.
internal (element) fuse
A device incorporated in the capacitor which disconnects an element or a group of elements in the event of breakdown.
insulation voltage (Ui)
The RMS rated value of the insulation voltage of capacitive elements and terminals to case or earth. If not specified, the RMS value of the insulating voltage is equivalent to the rated voltage divided by a square root of 2.
interphase transformer
An electromagnetic device enabling the operation in parallel of two or more phase displaced commutating groups through inductive coupling between the windings placed, on the same core.
inversion factor
For inversion, the ratio of the fundamental output power to the DC power.
ideal no-load direct voltage
The theoretical no-load direct voltage of an AC/DC converter assuming no reduction by phase control, no threshold voltages of electronic valve devices, and no voltage rise at small loads.
idle interval (of a valve arm)
That part of an elementary period in which the valve arm does not conduct.
ionic valve device
filled valve device
An electronic valve device in which the effects of the ionization of a gas play an important role.
(electronic) (power) inversion
Electronic conversion from DC to AC
inverter
AC/DC converter for inversion.[r]
J Edit
jumping characteristic
The property of an equipment to jump from one characteristic to another, e.g. by changing the predetermined value of a stabilizing device.
L Edit
latching valve device
A controllable valve device which latches when it is turned on, that means it remains in the on state when the trigger signal has ended.[s][t][u]
line commutation
An external commutation where the commutating voltage is supplied by the line.
load commutation
An external commutation where the commutating voltage is taken from a load other than the line.
lowest operating temperature (θmin) (capacitor)
The lowest temperature at which the capacitormay be energized.
M Edit
machine commutation
External commutation where the commutating voltage is supplied by a rotating machine.
maximum current (Imax) (capacitor)
The maximum RMS current for continuous operation.
maximum loss power (Pmax) (capacitor)
The maximum loss power with which the capacitor may be loaded at the maximum case temperature.
maximum operating temperature (θmax) (capacitor)
The highest temperature of the case at which capacitor may be operated.
maximum peak current (i) (capacitor)
The maximum current amplitude which occurs instantaneously during continuous operation.
maximum surge current (is) (capacitor)
The admissible peak current induced by a switching or any other disturbance of the system which is allowed for a limited number of times.
metal-foil capacitor (non self-healing)
A capacitor in which the electrodes usually consist of metal foils separated by a dielectric, in the event of breakdown of the dielectric, the capacitor does not restore itself.
model capacitor
A smaller unit which simulates a complete unit or element in an electrical test, without reducing the severity of the electrical, thermal or mechanical conditions.[v]
multi-connected converter
A converter consisting of two or more converter units parallel connected or series connected or both, each of which is an operative converter of its own.
multiple connection (of commutating groups)
A connection in which two or more identical commutating groups which do not commutate simultaneously are connected in such a way that their direct currents add.
multicycle control
The process of varying the ratio of the number of cycles which include current conduction to the number of cycles in which no current conduction occurs.
multicycle control factor
The ratio between the number of conducting cycles and the sum of conducting and non-conducting cycles in the case of multicycle control.
N Edit
natural characteristic (of a line commutated converter)
A characteristic determined only by the basic parts of the equipment, e.g. transformer and valve device assembly.
non-conducting direction (of an electronic valve device or of a valve arm)
The reverse of the conducting direction.
non-controllable connection
A uniform connection with all principal arms non-controllable.
non-controllable valve device
rectifier diode
A reverse blocking valve device the current path of which conducts in its conducting direction without any control signal being applied.
non-recurrent surge voltage (Us) (capacitor)
A peak voltage induced by a switching or any other disturbance of the system which is allowed for a limited number of times and for durations shorter than the basic period.
non-reverse blocking valve device
A controllable valve device which is not capable of blocking any voltage of more than several volts in its non-conducting direction.[w]
non-uniform connection
A connection with both controllable and non-controllable principal arms.
O Edit
off state
forward blocking state
The non-conducting state of a controllable valve device or an arm consisting of such devices when load current in the conducting direction is not allowed to flow due to the absence of a turn-on signal.
on state
conducting state
The condition when conducting current flows through an electronic valve device or an arm.
one-quadrant converter
An AC/DC or DC converter with one possible direction of DC power flow.
operating temperature (capacitor)
The temperature of the hottest point on the case of the capacitor in thermal equilibrium.
overpressure disconnector
A disconnecting device designed to interrupt the current path in the case of abnormal increase of the internal pressure.
P Edit
pair of antiparallel arms
Two valve arms in parallel with opposite conducting directions.
pair of arms
Two series connected valve arms with the same conducting direction.
parallel operation
A mode of operation of stabilized power supplies in which all similar output terminals are connected together and arranged so that the total load is shared by all the supplies.
phase control factor
In the case of phase control, the ratio of the voltage at prevailing current delay angle to the voltage at zero current delay angle, all voltage drops being assumed to be zero.
phase converter
An AC converter for changing the number of phases.
phase control
The process of varying the instant within the cycle at which current conduction in an electronic valve device or a valve arm begins.
power electronics
The field of electronics which deals with the conversion or switching of electric power with or without control of that power.
principal arm
A valve arm involved in the major transfer of power from one side of the converter or electronic switch to the other.[x]
pulse control
The process of varying the starting or termination instants or both of a repeated current conduction in a principal arm.
pulse control factor
The conduction ratio of a principal arm in the case of pulse duration control, assuming the commutation inductance to be zero.
pulse frequency (fp) (capacitor)
The repetition rate of periodic current pulses.
pulse frequency control
Pulse control at variable frequency and fixed pulse duration.
pulse frequency control
Pulse control at variable frequency and fixed pulse duration.
pulse number
The number of non-simultaneous symmetrical direct or indirect commutations from one principal arm to another which occur during one elementary period.
pulse width modulation control
PWM control (abbreviation)
Pulse control in which the pulse width or frequency or both are modulated within each fundamental period to produce a certain output waveform.
Q Edit
quenching
The termination of current flow in an arm without commutation.
quenching voltage
The voltage which causes quenching of the current.
P Edit
power electronic capacitor
A power capacitor intended to be used in power electronic equipment and capable of operating continuously under non-sinusoidal current or voltage.
R Edit
reactive power converter
A converter for reactive power compensation that generates or consumes reactive power without the flow of active power except for the power losses in the converter.
rated AC voltage (Un) (capacitor)
The maximum operating peak recurrent voltage of either polarity of a reversing type waveform for which the capacitor has been designed.[y][z][aa]
rated DC voltage (Un) (capacitor)
The maximum operating peak voltage of either polarity but of a non-reversing type wave form, for which the capacitor has been designed, for continuous operation.
real no-load direct voltage
The actual mean direct voltage at zero direct current.
(electronic) (power) rectification
Electronic conversion from AC to DC
rectification factor
For rectification, the ratio of the DC power to the fundamental input power.
rectifier
An AC/DC converter for rectification.
regenerative arm
A valve arm which transfers a part of the power from the load side to the source side.
(electronic) (power) resistance control
Control using the continuous variation of the resistance of electronic devices.
resistive direct voltage regulation
The direct voltage regulation due to resistance (threshold voltages of electronic valve devices excluded).
resonant converter
A converter using (a) resonant circuit(s) to provide commutation or to reduce switching losses.
resonant frequency (fr) (capacitor)
The lowest frequency at which the impedance of the capacitor becomes minimum.
reversible converter
A converter in which the direction of the power flow is reversible.
reverse blocking state
the non-conducting state of a reverse blocking valve device or an arm consisting of such devices when reverse voltage is applied between its main terminals (electrodes).
reverse blocking valve device
A valve device which is capable of blocking a specified direct voltage applied in its non-conducting direction.
reverse breakdown
A failure that permanently deprives a reverse blocking valve device or an arm consisting of such devices of its property to block reverse voltage.
ripple voltage (on the DC side)
The peak-to-peak alternating voltage component of the voltage on the DC side of a converter.
S Edit
slave operation
A mode of operation of stabilized power supplies achieving coordinated control of interconnected stabilized supplies by setting the master supply alone.
self-commutation
A commutation where the commutating voltage is supplied by components within the converter or the electronic switch.
self-healing metallized dielectric capacitor
A capacitor, the electrodes of which are deposited on the dielectric (usually by evaporation); in the event of breakdown of the dielectric, the capacitor restores itself.
semiconductor converter
An power converter with semiconductor valve devices.[ab]
semiconductor switch
An electronic power switch with semiconductor valve devices.[ac]
semiconductor valve device
An electronic valve device which is a semiconductor device.
sequential phase control
Asymmetrical phase control such that the delay angles are determined according to a given sequence.
single converter
A current stiff reversible AC/DC converter with direct current in one direction.
single-way connection (of a converter)
A converter connection such that the current through each of the phase terminals of the AC circuit is unidirectional.
snubber (circuit)
A subcircuit connected to one or more electronic valve devices in order to relieve it (them) of stress as for instance overvoltage transients, switching losses, high rate of rise of current or voltage, etc.[ad]
stabilized current characteristic
A characteristic with a stabilized output current.
stabilized output characteristic
A forced characteristic with an output quantity which is stabilized with respect to changes of influence quantities.
stabilized voltage characteristic
A characteristic with a stabilized output voltage.
stabilization
In the field of power electronics the reduction of the effect of changes of influence quantities on the output quantity.
stabilized power supply
In the field of power electronics an equipment which takes electrical energy from a source and supplies it stabilized by means inside the equipment to one or more pairs of output terminals.
stage (of a series connection)
A part of a series connection of two or more converter connections consisting of one or more parallel connected converter connections.
steady-state condition (capacitor)
Thermal equilibrium attained by the capacitor at constant output and at constant cooling-air temperature.
symmetrical phase control
Phase control with equal delay angles in all principal arms of a fully controllable converter connection or commutating group.
switched valve device
A controllable valve device which may be turned on and off by a control signal.
T Edit
tangent of the loss angle (tanδ) of a capacitor
The ratio between the equivalent series resistance and the capacitive reactance of a capacitor at specified sinusoidal alternating voltage and frequency.
threshold voltage (of an electronic valve device)
The value of the voltage obtained at the intersection of the voltage axis and the straight line approximation of the on-state characteristic of an electronic valve device.
transfer factor (of a DC converter)
The ratio of the voltage on the load side and the voltage on the source side.
transition current
The mean direct current of a converter connection when the direct current(s) of the commutation group(s) become(s) intermittent when decreasing the current.
trigger advance angle
The time expressed in angular measure by which the trigger pulse is advanced with respect to the reference instant.[ae]
trigger delay angle
The time expressed in angular measure by which the trigger pulse is delayed with respect to the reference instant in the case of phase control.[af]
triggering
The control action to achieve firing of a latching valve device or an arm consisting of such devices.
tolerance band
With stabilized power supplies the range of steady-state values of a stabilized output quantity lying between specified limits of deviation from a preset value, e.g. a nominal value.
total direct voltage regulation
The direct voltage regulation including the effect of the AC system impedance.
total harmonic distortion THD
The ratio of the rms value of the harmonic content of an alternating quantity to the rms value of the fundamental component of the quantity.
turn-off arm
An auxiliary arm which temporarily takes over the current directly from a conducting valve arm, consisting of one or more latching valve devices which cannot be turned off by a control signal.
two-quadrant converter
An AC/DC or DC converter with two possible directions of DC power flow associated with one direction of direct current and two directions of direct voltage or vice versa.
U Edit
uniform connection
A connection with either all principal arms controllable or all principal arms non-controllable.
V Edit
valve device assembly
An electrically and mechanically combined assembly of electronic valve devices or stacks, complete with all its connections and auxiliaries in its own mechanical structure.[ag]
valve device blocking
An operation to prevent further turn-on of a controllable valve device or an arm consisting of such devices by inhibiting the control signals.
valve device commutation
A method of self-commutation in which the commutating voltage is created by turning off the conducting electronic valve device by a control signal.[ah]
valve device quenching
A method of quenching in which the quenching is performed by the electronic valve device itself.
valve device stack
A single structure of one or more electronic valve devices with its (their) associated mounting(s) and auxiliaries if any.
voltage stiff AC/DC converter
An electronic AC/DC converter having an essentially smooth voltage on the DC side provided e.g. by a low impedance path for the harmonic currents.
voltage source inverter
voltage fed inverter
A voltage stiff inverter.
Annuity
A fixed sum of money paid to someone every year, often as a pension.
Asset
An item of property owned by a person or company regarded as having a value, and which can meet a debt.
Back of House
Support personnel in a financial services company.
BACS
"Bankers' Automated Clearing Services" - electronic financial transaction service, often used to pay employees.
Bail out
The giving of financial assistance to a failing business to save it from collapse.
Bank of England
The central bank for the UK. It acts as the government's bank, issues currency, oversees monetary policy and sets interest rates.
BIC
Bank Identifier Code - a number used to identify each bank and branch.
Blue chip
Adjective used to describe high quality and specifically in the banking world to describe stocks which are a reliable investment, but less so than gilt-edged stock. Originates either from a high value poker chip, or from a sliver of diamond.
Bond
A loan to a corporate or government for a defined period at a fixed interest rate.
Boom and bust
A process of economic expansion and contraction, often in repeated cycles.
Boutique
An investment bank which offers some but not all banking services, generally in corporate finance.
Broker
A person who buys and sells stocks for others in return for a commission.
Budget, the
Government's plans for the fiscal year.
Bulge bracket
The largest multinational investment banks.
Capital
Assets which are available for a purpose such as investment or starting a company. It is different to money because money is used only to purchase things, capital is used to generate wealth, e.g. through investment.
Capital market
The financial system which raises capital by dealing in shares, bonds and long term investments.
Cash flow
The amount of money being transferred in and out of a business, affecting liquidity.
Chancellor of the Exchequer
The chief finance minister of the UK who prepares the Budget.
Collateral
Assets that are offered to secure a loan or type of credit
Commodity
A raw material that can be bought or sold such as coffee or coal.
Credit
A payment received. Alternatively, an agreement to repay something of value in the future. Thirdly, the borrowing capacity of a person or company.
Credit rating
An assessment of a particular issuer's credit worthiness which results in a rating being assigned. Ratings range from AAA (very high) to D (in default). Several companies study issuers and make ratings decisions, including Moody's and Standard & Poor's.
Debit
A payment made.
Default
Failure to repay a loan.
Diversification
The strategy of investing broadly across a number of different investments to reduce risk; a hallmark of mutual fund investing.
Domiciled
Reside or be based.
Duty
A tax levied on goods not humans
Emerging market
A country which is developing the characteristics of a developed market, but is not yet fully developed. Normally a country experiencing rapid growth and industrialisation.
Exposure
Being placed at risk of financial losses.
Financial Instrument
A document involving monetary value which can be equity based, represent ownership of an asset or represent a loan made to an owner of an asset. They are tradeable packages of capital. Essentially, it is an equity, asset or loan.
Fiscal
Government revenue, e.g. taxes.
Freddie Mac and Fannie Mae
Two American institutions involved with mortgages. They were heavily involved in the causes of the credit crunch of 2008 as they were over exposed to risk.
Front Office
The sales personnel and finance employees - normally where revenues are generated.
FTSE 100
"Financial Times Stock Exchange", pronounced "futsie" - a share index of 100 companies on the London Stock Exchange with the highest market capitalisation. Its rises and falls are used as a gauge of business prosperity.
GDP
"Gross Domestic Product" - the monetary value of all the finished goods and services produced within a country's borders in a specific time period, usually annually.
Gold Standard
A now obsolete exchange whereby the value of a currency is defined by gold.
Golden Rule of Banking
Short term transactions should be financed with short term money, and long term transactions with long term funds.
Gordon Gekko
Fictional stockbroker from the 1987 film Wall Street who has become a byline for greed thanks to his (mis)quote "greed is good".
Government bond
A bond issued by a national government to finance spending. While this means the bond is free of credit risk because the government can always pay the debt by raising taxes or printing money, it does depend on a stable political system.
Gross
The full amount of income, profit or interest without any deductions from tax or costs.
Hedge
An attempt to protect against loss on a bet or investment by making a compensating transaction.
Hedge fund
Investments of a few (normally wealthy) people pooled together and managed professionally. Their goal is to aggressively maximise return on the investment but the term actually originates from their previous strategy of "hedging risk".
HMRC
"Her Majesty's Revenue and Customs" - the UK Government department tasked with collecting taxes, paying some forms of state support and administering some regulatory regimes such as the national minimum wage.
Holding company
A parent corporation, limited liability company or limited partnership that owns enough voting stock in another company to control its policies and management. This means the holding company is protected against the other company's losses or liabilities, but reaps the rewards of its profits. It can also be based in jurisdictions with lower tax rates while allowing the other company to continue to operate wherever.
IMF - International Monetary Fund
Created to promote monetary and exchange stability in the global economy. This means it monitors financial developments around the world and lends funds to needy countries.
Inflation
An increase in prices which means that the purchasing power of money falls - in other words you get less for your money than you used to.
Interest
Money paid regularly as a charge for borrowing money, typically an annual percentage rate.
IPO - Initial Public Offering
The first sale of a company's shares to the public, also known as a stock market listing or flotation. Often used as a means for a young company to raise capital to expand.
Junk bond
Risky investments which can offer higher yields than safer bonds. Often issued by companies with a low credit rating as investors demand higher rewards as compensation for the risk of investing in them.
Lehman Brothers
A bank whose bankruptcy and collapse signalled the beginning of the 2008 credit crunch.
Leverage
Borrowing capital to finance an investment much larger than that which the borrower can afford with their own cash, in order to increase the potential return of the investment. For example, instead of using £200,000 to buy one house to sell on for £220,000, the investor could split their money across 10 houses priced at £200,000 and pay £20,000 to each and borrow the money to pay the rest.
Then they could sell the houses for £220,000 x 10 and make £200,000 profit, not the £20,000 they make on buying a house entirely with their own money. The bigger the ratio of borrowed money to owned, the more leveraged they are. Likewise a company which has £10 million can borrow £20 million and have £30 million to spend on growth, without increasing its equity and diluting its shares.
Liability
A company's debts that arise during its business operations, e.g. loans.
LIBOR - London Interbank Offered Rate
A rate which some leading banks charge each other for short-term loans. It is used to calculate interest rates on loans throughout the world.
Liquidation
When a business is terminated or bankrupt, its assets are sold to pay creditors.
Liquidity
The measure of how quickly an investment can be turned into cash. A mutual fund generally is considered a very liquid investment, because shares can be redeemed at any time. In contrast, a house is a very illiquid investment.
LSE - London Stock Exchange
The primary stock exchange in the UK. It has 350 companies from 50 countries.
Maturity
The finite time period at the end of which the financial instrument stops and the principle is repaid with interest.
Merger
The combining of two or more companies.
Mezzanine
A type of financing which combines debt and equity financing. It is debt capital which gives the lender the right to ownership and equity if the loan is not paid. It is often quite high risk so it can also be high yield for the lender. The word is derived from the Latin for "middle" as the risk is medium.
Microfinance
A system to allow low-income individuals or groups who cannot access normal financial services to save, lend or insure themselves. Its goal is to make these low-income demographics become self-sufficient.
Net
Gross income which has had tax deducted.
Options
An agreement for the right to buy or sell a financial asset at an agreed price during a certain time period. If the price of the asset rises, the option buyer can buy it at the agreed lower price and sell for a profit. On the other hand, if the price drops, the option writer can sell at the agreed price which is now higher, making themselves a profit instead.
PAYE - Pay as you earn
Employers deduct income tax from employees' paycheques and remit it to the government.
Penny stock
Originally denoting stocks with less than a $1 a share, they now can refer to stocks with more worth but which still operate outside of the major exchanges. They are generally very illiquid.
Portfolio
The collective noun for financial assets held by investors or managed by financial professionals.
Public company
A company who has issued securities through an IPO and consequently the value of their company is determined by the markets.
Quarter
Three months of the financial calender, often used as a basis for reporting performance. Often expressed as Q1 Q2 Q3 and Q4.
Recession
When two consecutive quarters record negative economic growth.
Redeem
Repay a financial instrument at its maturity date.
Remittance
Sending money to pay a bill, invoice, tax or similar.
Retail banks
Banks which provide high street services such as savings accounts and mortgages.
Securities
A financial instrument which can be either a stock, a bond or an option.
Share index
A measure of change in an economy or securities market.
Shares
Either a financial asset or a unit of ownership interest in a company.
SME
Small and Medium Sized Enterprises
Speculation
Essentially the same as an investment but with a much higher risk of losing the initial outlay, though with a potential for a very high return. It sometimes has negative connotations such as irresponsibility.
Stocks
The same as shares and equity.
SWIFT - Society for Worldwide Interbank Financial Telecommunications
A system for secure financial transactions such as transfers.
Takeover
When one company buys another company. Occasionally a publicly listed company will be acquired in a hostile take over against its will when the buying company suddenly buys all the shares.
Tax avoidance
A legal attempt to minimise the amount of tax owed.
Tax evasion
An illegal attempt to mimimise the mount of tax owed.
The Treasury
Government department responsible for formulating and implementing financial and economic policy.
Trader
Someone who enagages in the transfer of financial assets in a market, but for a much shorter time than an investor.
Volatility
Volatility refers to the amount of fluctuation in price of a security. Generally speaking, the higher the volatility the riskier the investment.
Wall Street (NY Stock Exchange)
The original home of the New York Stock Exchange and historic headquarters of the largest US banks. A collective noun for the financial commnuity in NY.
Wolf of Wall Street
Jordan Belfort, the subject of a Leonardo diCaprio film, who was a stockbroker convicted of fraud.
World Bank
An international organisation dedicated to aiding developing nations by providing finance, advice and research.
Yield
The income return on an investment, usually expressed as a percentage based on the investment's cost.
