A device that protects AC-powered electrical devices from voltage spikes. A surge suppressor’s job is to stop transient high voltages by either blocking them or shunting them to ground. Many surge suppressors use MOVs (metal oxide varistors), often made from zinc oxide, which conduct electricity when the voltage exceeds a certain rating. Each time an MOV is hit with high voltage, it degrades a small amount; MOVs have a limited lifespan, which means that surge suppressors using this technology need to be replaced periodically. Other types of surge suppressor technology include diodes, gas discharge tubes, selenium “clamping” semiconductors, and more.
Important specs for surge suppressors include:
- Clamping voltage — the voltage above which the surge suppressor will block or shunt electricity. Low clamping voltage means better protection, but usually shorter suppressor life.
- Joules rating — the amount of energy the surge suppressor can absorb without failing.
- Response time — how long it takes the surge suppressor to respond to over-voltage. The longer the response time, the longer any connected equipment will be subjected to excessively high voltage.