Terms, definitions and abbreviations
3.1 Terms and definitions
surge protective device SPD
device that contains at least one nonlinear component that is intended to limit surge voltages
and divert surge currents
NOTE: An SPD is a complete assembly, having appropriate connecting means.
SPD having no intended series impedance
NOTE: A one port SPD may have separate input and output connections.
SPD having a specific series impedance connected between separate input and output connections
voltage switching type SPD
SPD that has a high impedance when no surge is present, but can have a sudden change in impedance to a low value in response to a voltage surge
NOTE: Common examples of components used in voltage switching type SPDs are spark gaps, gas tubes and thyristors. These are sometimes called “crowbar type” components.
voltage limiting type SPD
SPD that has a high impedance when no surge is present, but will reduce it continuously with
increased surge current and voltage
NOTE: Common examples of components used in voltage limiting type SPDs are varistors and avalanche breakdown diodes. These are sometimes called “clamping type” components.
combination type SPD
SPD that incorporates both, voltage switching components and voltage limiting components.
The SPD may exhibit voltage switching, limiting or both
short-circuiting type SPD
SPD tested according to Class II tests which changes its characteristic to an intentional internal short-circuit due to a surge current exceeding its nominal discharge current In
mode of protection of an SPD
an intended current path, between terminals that contains protective components, e.g. line- toline, line-to-earth, line-to-neutral, neutral-to-earth.
nominal discharge current for class II test In
crest value of the current through the SPD having a current waveshape of 8/20
impulse discharge current for class I test Iimp
crest value of a discharge current through the SPD with specified charge transfer Q and specified energy W/R in the specified time
maximum continuous operating voltage UC
maximum r.m.s. voltage, which may be continuously applied to the SPD’s mode of protection
NOTE: The UC value covered by this standard may exceed 1 000 V.
follow current If
peak current supplied by the electrical power system and flowing through the SPD after a discharge current impulse
rated load current IL
maximum continuous rated r.m.s. current that can be supplied to a resistive load connected to
the protected output of an SPD
voltage protection level UP
maximum voltage to be expected at the SPD terminals due to an impulse stress with defined voltage steepness and an impulse stress with a discharge current with given amplitude and waveshape
NOTE: The voltage protection level is given by the manufacturer and may not be exceeded by:
– the measured limiting voltage, determined for front-of-wave sparkover (if applicable) and the measured limiting voltage, determined from the residual voltage measurements at amplitudes corresponding to In and/or Iimp respectively for test classes II and/or I;
– the measured limiting voltage at UOC, determined for the combination wave for test class III.
measured limiting voltage
highest value of voltage that is measured across the terminals of the SPD during the application of impulses of specified waveshape and amplitude
residual voltage Ures
crest value of voltage that appears between the terminals of an SPD due to the passage of discharge current
temporary overvoltage test value UT
test voltage applied to the SPD for a specific duration tT, to simulate the stress under TOV conditions
load-side surge withstand capability for a two-port SPD
ability of a two-port SPD to withstand surges on the output terminals originating in circuitry downstream of the SPD
voltage rate-of-rise of a two-port SPD
rate of change of voltage with time measured at the output terminals of a two port SPD under specified test conditions
1,2/50 voltage impulse
voltage impulse with a nominal virtual front time of 1,2 μs and a nominal time to half-value of 50 μs
NOTE: The Clause 6 of IEC 60060-1 (1989) defines the voltage impulse definitions of front time, time to halfvalue and waveshape tolerance.
8/20 current impulse
current impulse with a nominal virtual front time of 8 μs and a nominal time to half-value of 20 μs
NOTE: The Clause 8 of IEC 60060-1 (1989) defines the current impulse definitions of front time, time to half-value and waveshape tolerance.
a wave characterized by defined voltage amplitude (UOC) and waveshape under open-circuit conditions and a defined current amplitude (ICW) and waveshape under short-circuit conditions
NOTE: The voltage amplitude, current amplitude and waveform that is delivered to the SPD are determined by the combination wave generator (CWG) impedance Zf and the impedance of the DUT.
open circuit voltage UOC
open circuit voltage of the combination wave generator at the point of connection of the device under test
combination wave generator short-circuit current ICW
prospective short-circuit current of the combination wave generator, at the point of connection of the device under test
NOTE: When the SPD is connected to the combination wave generator, the current that flows through the device is generally less than ICW.
SPD is thermally stable if, after heating up during the operating duty test, its temperature decreases with time while energized at specified maximum continuous operating voltage and at specified ambient temperature conditions
degradation (of performance)
undesired permanent departure in the operational performance of equipment or a system from its intended performance
short-circuit current rating ISCCR
maximum prospective short-circuit current from the power system for which the SPD, in conjunction with the disconnector specified, is rated Copyright International Electrotechnical Commission
SPD disconnector (disconnector)
device for disconnecting an SPD, or part of an SPD, from the power system
NOTE: This disconnecting device is not required to have isolating capability for safety purposes. It is to prevent a persistent fault on the system and is used to give an indication of an SPD’s failure. Disconnectors can be internal (built in) or external (required by the manufacturer). There may be more than one disconnector function, for example an over-current protection function and a thermal protection function. These functions may be in separate units.
degree of protection of enclosure IP
classification preceded by the symbol IP indicating the extent of protection provided by an enclosure against access to hazardous parts, against ingress of solid foreign objects and possibly harmful ingress of water
conformity test made on one or more items representative of the production[IEC 60050-151:2001, 151-16-16]
test made on each SPD or on parts and materials as required to ensure that the product meets the design specifications[IEC 60050-151:2001, 151-16-17, modified]
contractual test to prove to the customer that the item meets certain conditions of its specification[IEC 60050-151:2001, 151-16-23]
an electrical circuit intended to prevent surge energy from being propagated to the power network during energized testing of SPDs
NOTE: This electrical circuit is sometimes called a “back filter”.
Impulse test classification
class I tests
tests carried out with the impulse discharge current Iimp, with an 8/20 current impulse with a crest value equal to the crest value of Iimp, and with a 1,2/50 voltage impulse
class II tests
tests carried out with the nominal discharge current In, and the 1,2/50 voltage impulse
class III tests
tests carried out with the 1,2/50 voltage – 8/20 current combination wave generator
residual current device RCD
switching device or associated devices intended to cause the opening of the power circuit when the residual or unbalance current attains a given value under specified conditions
sparkover voltage of a voltage switching SPD
trigger voltage of a voltage switching SPD
maximum voltage value at which the sudden change from high to low impedance starts for a voltage switching SPD
specific energy for class I test W/R
energy dissipated by a unit resistance of 1 Ώ with the impulse discharge current Iimp
NOTE: This is equal to the time integral of the square of the current (W / R = ∫ i 2d t).
prospective short-circuit current of a power supply IP
current which would flow at a given location in a circuit if it were short-circuited at that location by a link of negligible impedance
NOTE: This prospective symmetrical current is expressed by its r.m.s. value.
follow current interrupt rating Ifi
prospective short-circuit current that an SPD is able to interrupt without operation of a disconnector
residual current IPE
current flowing through the PE terminal of the SPD while energized at the reference test voltage (UREF) when connected according to the manufacturer’s instructions
device that indicates the operational status of an SPD, or a part of an SPD.
NOTE: Such indicators may be local with visual and/or audible alarms and/or may have remote signalling and/or output contact capability.
contact included in a circuit separate from the main circuit of an SPD, and linked to a disconnector or status indicator
type of SPD with more than one mode of protection, or a combination of electrically interconnected SPDs offered as a unit
total discharge current ITotal
current which flows through the PE or PEN conductor of a multipole SPD during the total discharge current test
NOTE 1: The aim is to take into account cumulative effects that occur when multiple modes of protection of a multipole SPD conduct at the same time.
NOTE 2: ITotal is particularly relevant for SPDs tested according to test class I, and is used for the purpose of lightning protection equipotential bonding according to IEC 62305 series.
reference test voltage UREF
r.m.s. value of voltage used for testing which depends on the mode of protection of the SPD, the nominal system voltage, the system configuration and the voltage regulation within the system
NOTE: The reference test voltage is selected from Annex A based on the information given by the manufacturer according to 7.1.1 b8).
transition surge current rating for short-circuiting type SPD Itrans
8/20 impulse current value exceeding the nominal discharge current In, that will cause a shortcircuiting type SPD to short-circuit
Voltage for clearance determination Umax
highest measured voltage during surge applications according 8.3.3 for clearance determination
maximum discharge current Imax
crest value of a current through the SPD having an 8/20 waveshape and magnitude according
to the manufacturers specification. Imax is equal to or greater than In
Table 1 – List of Abbreviations
|ABD||avalanche breakdown device||126.96.36.199|
|CWG||combination wave generator||3.1.22|
|RCD||residual current device||3.1.35|
|DUT||device under test||General|
|IP||degree of protection of enclosure||3.1.29|
|SPD||surge protective device||3.1.1|
|k||trip current factor for overload behaviour||Table 20|
|Zf||fictive impedance (of combination wave generator)||8.1.4 c)|
|W/R||specific energy for class I test||3.1.37|
|T1 , T2 , and/or T3||product marking for test classes I, II and/or III||7.1.1|
|tT||TOV application time for testing||3.1.17|
|Abbreviations related to voltage|
|UC||maximum continuous operating voltage||3.1.11|
|UREF||Reference test voltage||3.1.45|
|UOC||open circuit voltage of the combination wave generator||3.1.22, 3.1.23|
|UP||voltage protection level||3.1.14|
|Umax||voltage for clearance determination||3.1.47|
|UT||temporary overvoltage test value||3.1.17|
|Abbreviations related to current|
|Iimp||impulse discharge current for class I test||3.1.10|
|Imax||maximum discharge current||3.1.48|
|In||nominal discharge current for class II test||3.1.9|
|Ifi||follow current interrupt rating||3.1.39|
|IL||rated load current||3.1.13|
|ICW||short-circuit current of the combination wave generator||3.1.24|
|ISCCR||short-circuit current rating||3.1.27|
|IP||prospective short-circuit current of the power supply||3.1.38|
|IPE||residual current at UREF||3.1.40|
|ITotal||total discharge current for multipole SPD||3.1.44|
|Itrans||transition surge current rating for short-circuiting type SPD||3.1.46|
4 Service conditions
Frequency range is from 47 Hz to 63 Hz a.c.
The voltage applied continuously between the terminals of the surge protective device (SPD)
must not exceed its maximum continuous operating voltage UC.
4.3 Air pressure and altitude
Air pressure is 80 kPa to 106 kPa. These values represent an altitude of +2 000 m to -500 m, respectively.
- normal range: –5 °C to +40 °C
NOTE: This range addresses SPDs for indoor use in weather-protected locations having neither temperature nor humidity control and corresponds to the characteristics of external influences code AB4 in IEC 60364-5-51.
- extended range: -40 °C to +70 °C
NOTE: This range addresses SPDs for outdoor use in non weather protected locations.
- normal range: 5 % to 95 %
NOTE This range addresses SPDs for indoor use in weather-protected locations having neither temperature nor humidity control and corresponds to the characteristics of external influences code AB4 in IEC 60364-5-51.
- extended range: 5 % to 100 %
NOTE This range addresses SPDs for outdoor use in non weather protected locations.
The manufacture shall classify the SPDs in accordance with the following parameters.
5.1 Number of ports
5.2 SPD design
5.2.1 Voltage switching
5.2.2 Voltage limiting
5.3 Class I, II and III tests
Information required for class I, class II and class III tests is given in Table 2.
Table 2 – Class I, II and III tests
|Tests||Required information||Test procedures (see subclauses)|
|Class I||Iimp||8.1.1; 8.1.2; 8.1.3|
|Class II||In||8.1.2; 8.1.3|
|Class III||UOC||8.1.4; 188.8.131.52|