The lowest three levels of protection defined in the UL rating are 330 V, 400 V and 500 V. A lower clamping voltage indicates better protection, but can sometimes result in a shorter life expectancy for the overall protective system.
UK type G socket adapter with surge protector Clamping voltage Īlso known as the let-through voltage, this specifies what spike voltage will cause the protective components inside a surge protector to short or clamp. Many protectors will connect to all three in pairs (line–neutral, line–ground and neutral–ground), because there are conditions, such as lightning, where both line and neutral have high voltage spikes that need to be shorted to ground. Sockets in a modern house uses three wires: line, neutral and ground. Surge protectors for homes can be in power strips used inside, or a device outside at the power panel. However, if the spike is large enough or long enough, like a nearby hit by lightning, there might not be enough power line or ground resistance and the MOV (or other protection element) can be destroyed and power lines melted. Since a spike lasts only 10s of microseconds, the temperature rise is minimal. The spike's energy is dissipated in the power lines (and/or the ground), or in the body of the MOV, converted to heat. The voltage is reduced as the shorting current flows through the resistance in the power lines. The most common and effective way is the shorting method in which the electrical lines are temporarily shorted together (as by a spark gap) or clamped to a target voltage (as by a MOV) resulting in a large current flow. Some surge protectors use multiple elements. Shorting is done by spark gaps, discharge tubes, zener-type semiconductors, and metal-oxide varistors (MOVs), all of which begin to conduct current once a certain voltage threshold is reached, or by capacitors which inhibit a sudden change in voltage. Blocking is done by using inductors which inhibit a sudden change in current. Long term surges may or may not be handled by fuses and overvoltage relays.Ī transient surge protector attempts to limit the voltage supplied to an electric device by either blocking or shorting current to reduce the voltage below a safe threshold. Even tens of milliseconds can be longer than a protector can handle. Long term surges can destroy the protectors in an entire building or area. Spikes can also occur on telephone and data lines when AC main lines accidentally connect to them or lightning hits them, or if the telephone and data lines travel near lines with a spike and the voltage is induced.Ī long term surge, lasting seconds, minutes, or hours, caused by power transformer failures such as a lost neutral or other power company error, are not protected by transient protectors. Spikes can degrade wiring insulation and destroy electronic devices like light bulbs, battery chargers, modems and TVs etc. A motor when switched off can generate a spike of 1,000 or more volts. Lightning that hits a power line can give many thousands, sometimes 100,000 or more volts. In an AC circuit a voltage spike is a transient event, typically lasting 1 to 30 microseconds, that may reach over 1,000 volts.
MAX 6 SURGE PROTECTOR SERIES
6.10 Series mode (SM) surge suppressors.