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SPDC Terms Glossary

Each entry in this glossary consists of the term, letter symbol (if any), its definition(s) and document source(s) in square brackets. When a term has multiple definitions, these are grouped under a single term. If there is a preferred definition for a multiple definition term, this is shown in bold text. Definitions added since 2001 are shown in italic text. Non-preferred definitions are shown in underlined text. When the same definition appears in “The Authoritative Dictionary of IEEE Standards Terms 7th Edition”, STD. 100-2000 appears in the source document list.

For easy access to the large list of terms, the terms are arranged in the following first letter groups:

A-B, C, D-E, F-H, I-L, M-N, O-Q, R, S, T-U, V-Z

Clicking the appropriate letter group takes you to the terms and definitions page for that group. The most up to date version of this glossary is available to SPD Forum members in the SPD Forum Bibliography subcommittee SPDC Dictionary folder.

The groups of terms in this glossary are shown below. Most browsers support the “Find in this page” function (Ctrl+F) in the Edit menu and this can be used to find a specific term.

Terms A-B

ac standby power (varistor), acceptance test, air discharge method, air gap surge arrester, air gap surge protector, air insulation and switchgear, ambient temperature, anode, antistatic, approach speed, arc current, arc voltage, arrester discharge current, arrester discharge voltage, arrester disconnector, arrester duty cycle rating, arrester rating (for silicon carbide arresters only), arrester recovery voltage, arrester sparkover, arrester unit, arrester, deadfront type, arrester, distribution, heavy duty class, arrester, distribution, light duty class, arrester, distribution, normal duty class, arrester, riser pole type, back filter, backup air-gap device, basic impulse insulation level (BIL), basic lightning impulse insulation level, basic switching impulse insulation level (BSL), bidirectional thyristor, blind spot, blocking, body/finger ESD, body/metal ESD, breakdown, breakdown, breakdown current, breakdown region, breakdown voltage, breakdown voltage, ac, breakdown voltage, dc , breakover current, breakover point, breakover voltage, brush-by

Terms C

capacitance (varistor), capacitance, cathode, certification tests, characteristic, charge voltage, circuit pack, clamping factor, clamping voltage, classes of grounding, classification current, classification of arresters, clearing, clearing source, coefficient of grounding, conformance test, contact discharge method, conventional BIL, conventional BSL, coordination of insulation, coupler, coupling factor, coupling network, coupling wire, crest (peak) value (of a wave, surge, or impulse), critical rate of rise of on-state current, current turnoff time

Terms D-E

dc holdover, dc holdover voltage, dc standby current (varistor), decoupling network, deflector, design tests, des, diode, direct ESD event, discharge counter, discharge current, discharge indicator, discharge voltage, discharge withstand current rating, discharge-voltage-current characteristic, disruptive discharge, duty cycle voltage rating, dynamic impedance (varistor), equipment under test (EUT), equipment victim , ESD current wave, ESD event, ESD

Terms F-H

fail-safe, fast approach, fault current, fault-current withstand, flashover, follow (power) current, forward current, forward voltage, forward/reverse conducting quadrant, forward-conducting diode thyristor SPD, forward-conducting triode thyristor SPD, front-of-wave impulse sparkover voltage, furniture ESD, gapless, gas-tube surge arrester, gate, gate reverse current, adjacent terminal open, gate reverse current, forward conducting state, gate reverse current, main terminals short circuited, gate reverse current, on-state, gate switching charge, gate-to-adjacent terminal breakover voltage, gate-to-adjacent terminal peak off-state voltage, glow current, glow voltage, glow-to-arc transition current, grading or control ring, ground end (of a neutral grounding device), ground potential rise, ground terminal, grounded parts, grounded system, ground-fault neutralizer grounded, ground-fault neutralizer, grounding device, grounding transformer, hand/metal ESD, hand-to-metal impedance, holding current

Terms I-L

impedance grounded, impedance voltage, impulse, impulse flashover voltage, impulse protective level, impulse protective volt-time characteristic, impulse reset time, impulse sparkover voltage, impulse sparkover voltage-time curve (arrester), impulse sparkover volt-time characteristic, impulse tests, impulse wave, impulse withstand voltage, incremental surge resistance, indirect ESD event, indoor arrester, induced-potential test, inert gas-pressure system, inhibited oil, initial current pulse, initial slope, insulation class (of a grounding device), insulation level, insulation resistance, intruder electrode geometry, intruder, ionization current, ionization voltage, let-through sparkover, lifetime rated pulse currents (varistor), lifetime rated pulse currents, lightning overvoltage, lightning surge, lightning, line end (of a neutral grounding device), line terminal, longitudinal (common) mode voltage, losses (of a grounding device)

Terms M-N

main discharge current wave, mains, main terminals, main terminal 1, main terminal 2, maximum (highest) system voltage, maximum continuous operating voltage (MCOV), maximum junction temperature, maximum rating; absolute maximum rating, means of grounding, mechanical limit, metal-oxide surge arrester (MOSA), methods (or types) of grounding, minimum impulse flashover voltage, multiple ESD event, negative differential-resistance (region), negative-breakdown resistance thyristor SPD, neutral ground capacitor, neutral grounding device, neutral grounding impedor, neutral grounding reactor, neutral grounding resistor, neutral grounding wave trap, n-gate thyristor, nominal rate of rise (of an impulse wave front), nominal system voltage, nominal varistor voltage, nonlinear exponent, non-repetitive current rating, non-repetitive peak forward current, non-repetitive peak on-state current, non-repetitive peak pulse current, normalized rising slope

Terms O-Q

off state of a thyristor SPD, off-state capacitance, off-state current, off-state voltage, oil-immersed (for a grounding device), oil, on-state current, on-state (region), on-state voltage, operating duty cycle, oscillatory surge, outdoor arrester, overshoot duration (varistor), overshoot duration, overvoltage, parameter, peak forward recovery voltage, peak gate switching current, peak nominal varistor voltage, peak off-state gate current, peak pulse impulse current, permanently grounded device, p-gate thyristor, positive-breakdown-resistance thyristor SPD, power-frequency sparkover voltage, power-frequency withstand voltage, principal current, principal voltage, principal voltage-current characteristic, prorated section, proximity ESD, quadrant

Terms R

radio influence voltage (RIV), rated average power dissipation, rated continuous current, rated current (of a neutral device) (current rating), rated dc voltage (varistor), rated forward surge current, rated frequency (of a grounding device), rated multiple peak pulse power dissipation, rated peak single pulse transient current (varistor), rated recurrent peak voltage (varistor), rated rms voltage (varistor), rated single pulse transient energy (varistor), rated thermal current, rated time (time rating), rated time temperature rise (for a grounding device), rated transient average power dissipation (varistor), rated voltage, rating, reactance grounded, receptor electrode geometry, receptor, recovery voltage, remote earth (potential), repetitive peak forward current, repetitive peak off-state current, repetitive peak off-state voltage, repetitive peak on-state current, repetitive peak reverse current, repetitive peak reverse voltage, repetitive rating, reseal voltage rating of an arrester, resistance (varistor), resistance grounded, resistance method of temperature determination, response time (varistor), response time, reverse blocking quadrant, reverse direction, reverse-blocking diode thyristor SPD, reverse-blocking triode thyristor SPD, routine tests

Terms S

sag, sealed tank system, SED static electric discharge, series gap, short circuit, short time rating (of a grounding device), shunt gap, solidly grounded, sparkover, standard lightning impulse, standard switching impulses, starting temperature (for a grounding device), static dissipative, statistical BIL, statistical BSL, steady-state temperature rise (for a grounding device), subassembly, surge (surge-protective device), surge arrester, surge let-through, surge protector, surge remnant, surge response voltage, surge-protective device, susceptibility, swell, switching current, switching overvoltage, switching point, switching quadrant, switching resistance, switching voltage, system (circuit) voltage

Terms T-U

tap, temperature coefficient of breakdown voltage, temperature derating, temporary overvoltage, terminals, thermal current rating, thermal resistance, thermal resistance, thermometer method of temperature determination, thyristor, time to impulse sparkover, transfer time, transient thermal impedance, transition current, transition time, transverse (differential) mode voltage, traveling wave, triboelectric charging, triboelectric series, ungrounded, unidirectional thyristor SPD, uninhibited oil, unit operation

Terms V-Z

valve arrester, valve element, variation of holding current with temperature, varistor voltage, vent, virtual duration of wave front (of an impulse), (virtual) junction temperature, virtual zero point (of an impulse), voltage clamping ratio (varistor), voltage clamping ratio, voltage overshoot (varistor), voltage overshoot, voltage rating, voltage to ground, vulnerability, waveform, wavefront (of a surge or impulse), wave shape (of an impulse test wave), wave shape designation (of an impulse), wave shape of a rectangular impulse of current or voltage, wave tail (of an impulse), wave, withstand voltages