IEC 61643-331 pdf download

IEC 61643-331 pdf download Components for low-voltage surge protective devices – Part 331: Specification for metal oxide varistors (MOV)
1scope
This part of lEC 61643 is a test specification for metal oxide varistors (MOV), which are usedfor applications up to 1 000 v a.c. or 1 500 V d.c. in power line,or ‘telecommunication，orsignalling circuits. They are designed to protect apparatus or personnel, or both, from hightransient voltages.
This specification applies to MoVs having two electrodes and does not deal with hybriddevices. This specification also does not apply to mountings and their effect on the Mov’scharacteristics. Characteristics given apply solely to the Mov mounted only in the waysdescribed for the tests.
Normative references
The following referenced documents are indispensable for the application of this document.For dated references, only the edition cited applies. For undated references, the latest editionof the referenced document (including any amendments) applies.
IEC 60068-1:1988,Environmental testing – Part 1: General and guidance
IEC 60068-2-6:1995, Environmental testing – Part 2:Tests – Test Fc: Vibration (sinusoidal)
IEC 60068-2-14:1984,Environmental testing – Part 2: Tests – Test N: Change of temperature
IEC 60068-2-20:1979，Environmental testing – Part 2: Tests – Test T: Soldering
IEC 60068-2-29:1987,Environmental testing – Part 2:Tests -Test Eb and guidance:Bump
IEC 60068-2-52:1996，Environmental testing – Part 2: Tests – Test Kb: Salt mist，cyclic(sodium, chloride solution)
IEC 60068-2-78:2001，Environmental testing – Part 2-78: Tests – Test Cab: Damp heat’steady state
IEC 61643-1:1998，Surge protected devices connected to low-voltage power distributionsystems – Part 1: Performance requirements and testing methods
3Parametric terms, letter symbols and definitions
3.1ratings
either a limiting capability or a limiting condition beyond which damage to the MoV may occurNOTE A limiting condition may be either a maximum or a minimum.
3.1.1
single-pulse peak current ITM
rated maximum value which may be applied for a single impulse of specified waveform,without causing Mov failure
NOTE Unless otherwise specified, an 8/20 us waveshape is used. In some cases, the rated line voltage may alsobe applied.
3.1.2
multiple-pulse peak current ITsM
rated maximum value which may be applied for repetitive applications of an impulse ofspecified waveform, without causing Mov failure
NOTE Unless otherwise specified,an 8/20 us waveform is used.
3.1.3
multiple-pulse peak-current derating against pulse width
graphical representation of rated multiple-pulse peak current against rectangular pulse widthfor different numbers of impulses
NOTE Typically, curves are provided for indefinite，106，105，104，,103，102 and 10 pulses together with a single-pulse curve.
3.1.4
temperature derating curve
graphical representation of parameter derating against temperature
NOTE Typical parameters are rated voltage, impulse current, energy and average power dissipation.
3.1.5
single-pulse maximum energy wTM
rated maximum value which may be absorbed for a single pulse of a specified waveformNOTE Unless otherwise specified,2 ms rectangular pulse is used (IEc 60060).
3.1.6
maximum continuous voltage vM (see Figure 1)
voltage that may be applied continuously at a specified temperature
3.1.6.1
r.m.s. a.c. sinusoidal voltage (less than 5 % total harmonic distortion) that may be appliedcontinuously at a specified temperature