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A part of the circuit of a
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.
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 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.
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 a
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.
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.
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]
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
τ = capacitor current pulse width tp = system pulse duration fp = system pulse frequency Un = peak recurrent voltage i = peak currentFig. 1. Wave Forms
The time of current flow during the charging or discharging from one voltage value to another of the
capacitor.[i]
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.
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.
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.
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.
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).
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.
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.
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
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.
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
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.
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
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.
Pulse control in which the pulse width or frequency or both are modulated within each fundamental period to produce a certain output waveform.
Q
quenching
The termination of current flow in an arm without
commutation.
quenching voltage
The voltage which causes quenching of the current.
R
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.
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.
The peak-to-peak alternating voltage component of the voltage on the DC side of a
converter.
S
slave operation
A mode of operation of stabilized power supplies achieving coordinated control of interconnected stabilized supplies by setting the master supply alone.
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.
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.
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.
The ratio between the equivalent series resistance and the capacitive reactance of a
capacitor at specified sinusoidal alternating voltage and frequency.
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.
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.
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.
^AC capacitors may be used with dc voltage up to the rated voltage only by permission of the capacitor manufacturer.
^Sometimes an auxiliary arm temporarily fulfills more than one of the following functions: by-pass arm, free-wheeling arm, turn-off arm or regenerative arm.
^Unless otherwise stated, the capacitor, losses will be understood to include losses in fuses and discharge resistors forming an integral part of the capacitor.
^At high frequency, the capacitor losses are predominantly due to losses in connections, contacts, and electrodes.
^Characteristics are, for example, voltage, number of phases and frequency including zero frequency.
^In English, the two spellings "convertor" and "converter" are in use, and both are correct. In this document, the spelling "converter" is used in order to avoid duplications.
^Within this area, the output quantities are not well defined.
^Unless otherwise specified, the crossover area is given by the overlap of the load effect bands or of the tolerance bands.
^The pulse current waveform example are shown in Fig. 1.
^By creating an alternating voltage from successive waves of the higher frequency AC system the cycloconverter provides a lower output frequency.
^By creating an alternating voltage from successive voltage samples of suitable frequency and duration the cycloconverter provides a higher or lower output frequency.
^DC capacitors may be used with ac voltage only by permission of the capacitor manufacturer.
^With low values of the DC ripple factor this quantity is approximately equal to the ratio of the difference to the sum of the maximum and the minimum value.
^Typical electronic valve devices are thyristors, power rectifier diodes, power switching bipolar and field effect transistors and insulated-gate bipolar transistors (IGBT).
^Two or more electronic valve devices may be integrated on a common semiconductor chip (examples: a thyristor and a rectifier diode in a reverse conducting thyristor, a power switching field effect transistor with its inverse diode) or packaged in a common case (semiconductor power module). These combinations are to be considered as separate electronic valve devices.
^An AC converter for changing both the frequency and the voltage and possibly the number of phases is also called a frequency converter.
^Multiple overlap occurs in line commutated converters at high angles of overlap.
^In English, the two spellings "invertor" and "inverter" are in use, and both are correct. In this article, the spelling "inverter" is used in order to avoid duplications.
^Most latching valve devices can be turned off only by suppressing the current through the conducting path by external means.
^A gate turn-off (GTO) thyristor is a latching valve device which can be turned off by a control signal.
^A latching valve device may be reverse blocking or non-reverse blocking.
^The sum of stresses should always be considered, for instance, the sum of temperature, mechanical conditions and electrical stresses.
^In certain power electronic circuits such valve devices require means to suppress any reverse voltages, e.g. inverse parallel connected non-controllable valve devices (rectifier diodes).
^Depending on the mode of operation a principal arm may act as an auxiliary arm or vice versa.
^The waveform can have many shapes — An example is given in Fig. 1.
^The mean value of the waveform may be positive or negative.
^It is important to note that the nominal voltage is not a RMS value.
^Similar terms are used for converters in general or for specific kinds of converters and for converters with other or specific electronic valve devices, e.g. thyristor converter, transistor inverter.
^Similar terms are used for electronic switches or power controllers with specific electronic valve devices, e.g. thyristor controller, transistor switch.
^Specific terms as for instance RC snubber, parallel snubber, AC side snubber, etc. are in use.
^With line, machine or load commutated converters the reference instant is the zero crossing instant of the commutating voltage.
^With line, machine or load commutated converters the reference instant is the zero crossing instant of the commutating voltage. With AC controllers it is the zero crossing instant of the supply voltage. For AC controllers with inductive loads the trigger delay angle is the sum of the phase shift and the current delay angle.
^Similar terms are applied to stacks or assemblies comprising specific electronic valve devices, e.g. diode stack (rectifier diodes only), thyristor assembly (thyristors only or in combination with rectifier diodes).
^Simultaneously the next electronic valve device to conduct is turned on.
References
Attribution
This article incorporates text from this source, which is in the
public domain: IS 1885-27: Electrotechnical vocabulary. 27. New Delhi,
Bureau of Indian Standards. 2008.
This article incorporates text from this source, which is in the
public domain: IS 13648: Power electronics capacitors. New Delhi,
Bureau of Indian Standards. 1993.