SPD vs SA comparison

SPD  : Surge Protective Devices

SA  : Surge Arrestor

Basic functions

Protect electrical appliances by suppressing surge voltage

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

Development background (period)

After generalization of electrically sensitive equipment

Generalization of electrically sensitive equipment

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

Installation location (UL 1449)

Circuit breaker secondary side (load side)

Circuit breaker primary side (power side)

characteristic

- Low let-through voltage 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.

Applicable standards

IEEE

C62.41

C62.11

NEC

Article 285

Article 280