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Comparison of SPD (TVSS) and SA |
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SPD (TVSS) |
SA (Surge Arrestor) |
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Basic functions |
Protect electrical appliances by suppressing surge voltage |
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Function implementation |
Mainly for line-to-line surge voltage suppression Line-to-line insulation protection of equipment |
Mainly suppressing surge voltage between line and ground Earth-to-ground insulation protection of equipment |
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Development background (period) |
After generalization of electrically sensitive equipment |
Generalization of electrically sensitive equipment |
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Object of protection |
Protect electronic equipment such as computers and PLCs from circuit breaker switching surges |
Protection of linear loads such as transformers and motors from circuit breaker switching surges |
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Installation location (UL 1449) |
Circuit breaker secondary side (load side) |
Circuit breaker primary side (power side) |
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characteristic |
- Low surge protection level (VPL) to suit electronic equipment insulation - Long life expectancy - Even if damaged, there is less fragmentation. - Noise can be removed using a filter. |
- High surge limit voltage, suitable for general electrical appliance insulation (BIL) - Short life expectancy - When damaged, a lot of debris is scattered. - Noise cannot be removed. |
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Applicable standards |
IEEE |
C62.41 |
C62.11 |
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NEC |
Article 285 |
Article 280 |
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BIL Basic Impulse Insulation Level
IEEE C62.11-1999 IEEE Standard for Metal-Oxide Surge Arresters for AC Power Circuits (< 1 kV).
IEEE C62.41-1991 IEEE Recommended Practice on Surge Voltages in Low-Voltage AC Power Circuits
NEC Article 280 Surge Arresters
NEC Article 285 Transient Voltage Surge Suppressors, New in 2002 Edition
SPD Surge Protective Device, Surge suppressor, term used by IEC, IEEE
NEMA National Electrical Manufacturers Association, a union of electrical manufacturers, uses SPD and TVSS interchangeably