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SPDC Terms F-H
FAIL-SAFE
Use of this term is not recommended in C62 series documents.
[C62.32–1987]
FAST APPROACH
Approach speeds that engender short, sub-nanosecond rise-time ESD current waves. Fast approach speed depends on the voltage difference between the intruder and receptor, e.g. for rounded electrodes of 8 mm diameter, greater than 0.05 m/s, l m/s, and 10 m/s at charge voltages of 4 kV, 8 kV and 16 kV respectively.
[C62.47–1992]
FAULT CURRENT
The current from the connected power system that flows in a short circuit.
[C62.1–1989 & C62.11–1987]
FAULT-CURRENT WITHSTAND
The maximum rms symmetrical fault current of a specified duration that a failed distribution class arrester will withstand without an explosive fracture of the housing.
[C62.1–1989]
FLASHOVER
A disruptive discharge around or over the surface of a solid or liquid insulator.
[C62.1–1989 & C62.2–1987 & C62.11–1987 & C62.22–1991]
FOLLOW (POWER) CURRENT
The current from the connected power source that flows through an arrester during and following the passage of discharge current.
[C62.31–1987 & C62.1–1989 & C62.2–1987 & C62.32–1987]
FORWARD CURRENT
(IF)
The current through the device in the forward conducting state.
[C62.37–1996]
FORWARD DIRECTION
(1) The direction of current in a p-n junction that results when the p-type semiconductor region is at a positive potential relative to the n-type region.
(2) The direction of current in a semiconductor device that results when the p-type semiconductor region connected to one terminal is at a positive potential relative to the n-type region connected to the other terminal.
NOTE-This definition does not apply if one or more junctions are connected in series with at least one other junction whose p and n regions are reversed.
[C62.37–1996]
FORWARD VOLTAGE
(VF)
The voltage across the device in the forward conducting state at a specified current IF
[C62.37–1996]
Peak voltage measured across the avalanche surge suppressor for a specified forward pulse current IFS. Applies to asymmetrical bi-directional avalanche junction surge suppressor only.
[C62.35–1987]
FORWARD/REVERSE CONDUCTING QUADRANT
A quadrant of the principal voltage-current characteristic in which the device exhibits a forward direction conduction state. This will be quadrant 1 for a forward conducting thyristor SPD and quadrant 3 for a reverse conducting thyristor SPD.
[C62.37–1996]
FORWARD-CONDUCTING DIODE THYRISTOR SPD
A two-terminal internally triggered thyristor SPD that switches only for negative terminal-2 (cathode) voltage and conducts large currents at positive terminal-2 voltages comparable in magnitude to the on-state voltage.
NOTES:
1 In conventional thyristor applications where the cathode is the common terminal, this device would be called a reverse-conducting diode thyristor.
2 When terminal 2 (cathode) is positive, the device characteristics are similar to those of a forward biased diode.
3 When terminal 2 (cathode) is negative, the device characteristics are similar to those of a breakover-triggered SCR.
[C62.37–1996]
FORWARD-CONDUCTING TRIODE THYRISTOR SPD
A three-terminal thyristor SPD that switches only for negative main terminal-2 (cathode) voltage and conducts large currents at positive main terminal-2 voltages comparable in magnitude to the on-state voltage.
NOTES:
1 In conventional thyristor applications where the cathode is the common terminal, this device would be called a reverse-conducting triode thyristor.
2 Application of an appropriate fixed gate voltage allows switching to take place at voltages well below the intrinsic breakover value.
3 When main terminal 2 (cathode) is positive, the device characteristics are similar to those of a forward biased diode.
[C62.37–1996]
FRONT-OF-WAVE IMPULSE SPARKOVER VOLTAGE
The impulse sparkover voltage with a wave front that rises at a uniform rate and causes sparkover on the wave front.
[C62.11–1987]
FURNITURE ESD
An electrostatic discharge in which the intruder is an inanimate object such as a cart or chair, with or without a human in electrical contact with the object.
[C62.47–1992]
GAPLESS
Not possessing gaps, series or parallel, as in "gapless arrester".
[C62.11–1987]
GAS-TUBE SURGE ARRESTER
A gap, or gaps, in an enclosed discharge medium, other than air at atmospheric pressure, designed to protect apparatus or personnel, or both, from high transient voltages.
[C62.31–1987]
GATE
An electrode connected to one of the semiconductor regions to introduce a control current.
[C62.37–1996]
GATE REVERSE CURRENT, ADJACENT TERMINAL OPEN
(IGAO, IGKO)
The current through the gate terminal when a specified gate bias voltage, VG, is applied and the cathode terminal for a p-gate device or anode terminal for an n-gate device is open circuited.
[C62.37–1996]
GATE REVERSE CURRENT, FORWARD CONDUCTING STATE
(IGAF, IGKF)
The current through the gate terminal when a specified gate bias voltage, VG, is applied and a specified forward conduction current, IF, is flowing.
[C62.37–1996]
GATE REVERSE CURRENT, MAIN TERMINALS SHORT CIRCUITED
(IGAS, IGKS)
The current through the gate terminal when a specified gate bias voltage, VG, is applied and the cathode terminal for a p-gate device or anode terminal for an n-gate device is short circuited to the third terminal.
[C62.37–1996]
GATE REVERSE CURRENT, ON-STATE
(IGAT, IGKT)
The current through the gate terminal when a specified gate bias voltage, VG, is applied and a specified on-state current, IT is flowing.
[C62.37–1996]
GATE SWITCHING CHARGE
(QGS )
The charge through the gate terminal, under impulse conditions, during the transition from the off-state to the switching point, when a specified gate bias voltage, VG, is applied.
[C62.37–1996]
GATE-TO-ADJACENT TERMINAL BREAKOVER VOLTAGE
(VGK(BO); VGA(BO))
The gate to cathode voltage for a p-type device or gate to anode voltage for an n-gate device at the breakover point. This is equivalent to the voltage difference between the breakover voltage, V(BO), and the specified gate voltage, VG.
[C62.37–1996]
GATE-TO-ADJACENT TERMINAL PEAK OFF-STATE VOLTAGE
(VGDM)
The maximum gate to cathode voltage for a p-gate device or gate to anode voltage for an n-gate device that may be applied such that a specified off-state current, ID, at a rated off-state voltage, VD, is not exceeded.
[C62.37–1996]
GLOW CURRENT
The current that flows after breakdown when circuit impedance limits the follow current to a value less than the glow-to-arc transition current. It is sometimes called the glow mode current.
[C62.31–1987]
GLOW VOLTAGE
The voltage drop across the arrester during glow-current flow. It is sometimes called the glow mode voltage.
[C62.31–1987]
GLOW-TO-ARC TRANSITION CURRENT
The current required for the arrester to pass from the glow mode into the arc mode.
[C62.31–1987]
GPR
Acronym for ground potential rise. see: ground potential rise.
[C62.23 – 1995]
GRADING OR CONTROL RING
A metal part, usually circular or oval in shape, mounted to modify electrostatically the voltage gradient or distribution.
[C62.1–1989 & C62.11–1987]
GROUND END (OF A NEUTRAL GROUNDING DEVICE)
The end or terminal that is grounded directly or through another device.
[STD 32–1990]
GROUND POTENTIAL RISE
The voltage that a station grounding grid may attain relative to distant grounding point assumed to be at the potential of remote earth.
[C62.23–1995]
GROUND TERMINAL
The conducting part provided for connecting the arrester to ground.
[C62.1–1989 & C62.11–1987]
GROUNDED PARTS
Parts that are intentionally connected to ground.
[STD 32–1990]
GROUNDED SYSTEM
An electric system in which at least one conductor or point (usually the neutral conductor or neutral point of transformer or generator windings) is intentionally grounded, either solidly or through a grounding device.
[C62.1–1989]
A system of conductors in which at least one conductor or point (usually the neutral conductor or neutral point of transformer or generator windings) is intentionally grounded, either solidly or through a current-limiting device.
[STD 32–1990 (C62.91)]
GROUND-FAULT NEUTRALIZER GROUNDED
Reactance grounded through such values of reactance that, during a fault between one of the conductors and earth. the rated-frequency current flowing in the grounding reactances and the rated-frequency capacitance current flowing between the unfaulted conductors and earth shall be substantially equal. In the fault, these two components of fault current will be substantially 180 degrees out of phase.
NOTE: When a system is ground-fault neutralizer grounded, it is expected that the quadrature component of the rated-frequency single-phase-to-ground fault current will be so small that an arc fault in air will be self extinguishing.
[STD 32–1990]
GROUND-FAULT NEUTRALIZER
A grounding device that provides an inductive component of current in a ground fault that is substantially equal to and therefore neutralizes the rated-frequency capacitive component of the ground-fault current, thus rendering the system resonant grounded.
[STD 32–1990]
GROUNDING DEVICE
An impedance device used to connect conductors of an electric system to ground for the purpose of controlling the ground current or voltage to ground.
NOTE: The grounding device may consist of a grounding transformer or a neutral grounding device, or a combination of these. Protective devices, such as lightning arresters, may also be included as an integral part of the device.
[STD 32–1990]
GROUNDING TRANSFORMER
A transformer intended primarily to provide a neutral point for grounding purposes.
NOTE: It may be provided with a delta winding in which resistors or reactors may be connected.
[STD 32–1990]
HAND/METAL ESD
An electrostatic discharge from an intruding human hand which occurs from an intervening metal object such as a ring, tool, key, etc. Also called hand/metal discharge.
[C62.47–1992]
HAND-TO-METAL IMPEDANCE
The impedance between the human hand and the metal object with which it is associated in a hand/metal ESD. The metal object is usually the intruder discharge electrode. Examples of hand-to-metal impedance include resistance and capacitance between the fingers and a key, between the wrist and a metal watch or bracelet, and between the hand and screwdriver.
[C62.47–1992]
HOLDING CURRENT (IH)
The minimum current required to maintain the device in the on-state.
[C62.37–1996]
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