If you’ve ever tried to research surge protectors, there is good chance you’ve also come across the term surge arrester. Surge arresters serve the same purpose as surge protectors, but they operate in an entirely different way. Where surge protectors use a parallel circuit design – diverting extra voltage to another line – surge arresters operate on a design called a series circuit. Rather than diverting the extra voltage, a series circuit “stores” the voltage and releases it gradually over time.

Gas discharge arrestors

Gas discharge arresters work much in the same way as household surge protector, but uses gas tubes rather than MOVs. Where MOVs use semiconductors, gas discharge arrestors use inert gas as the conductor between the hot line and the ground line.

The variable resistance of the MOVs is very important to the functionality of a surge protector. It allows the protector to divert extra voltage only when necessary, and once this voltage has been diverted, the hot line voltage returns to a normal level. Meanwhile, the standard current can continue to flow, so that the voltage to your electronics goes unchanged even in the case of a surge. To relate this back to the hose analogy, the MOVs act like a pressure sensitive valve that is only activated when the pressure gets too high. The same principle of variable resistance applies to surge arrestors. At a normal voltage level, the gas in a gas discharge arrester does not conduct electricity well. But when the voltage increases enough, it ionizes the gas, making it a strong conductor. Electrons pass through the conductive gas until voltage levels stabilize, and the gas is no longer ionized. In this way, the gas is naturally variable. So the overall process of diverting voltage is pretty much the same, the only real difference being the type of conductor.

Better or worse than a protector?

Some argue that the surge arresters are better at protecting your electronics. The argument is that they react more quickly than a surge protector because they don’t need to divert the voltage. Some also say that sending electricity to the ground line (as in a parallel circuit) can disrupt the electrical system in a building, thus series circuit designs are better as they avoid this potential problem. Another argument against common surge protectors is that MOVs themselves can blow in a power surge, rendering them useless. This is actually true, but probably not as big a concern as you might think. It’s rare to have a power surge strong enough to blow your surge protectors, and there are things you can do to help avoid this. Primarily, turning off your electronics when they are not in use, and making sure you don’t run too many devices off of one outlet. Furthermore, in a particularly massive power surge (like the one you’d see in a thunder strike), it doesn’t matter whether your system runs on a parallel circuit method or a series circuit. The excess of energy in a thunder will render both useless. For this reason, many advanced surge protectors include an arrestor as part of the circuitry.

Again, thunder related power surges are extremely uncommon, so this is no cause for alarm. If you’re especially worried about it, there are such things as lightning arresters. These tend to be costly, but they are specifically designed to handle power surges caused by lightning.