How a Surge Protector Works

A surge protector shields electronic devices from power surges. If you're curious as to how a surge protector works, the first question is, "What are power surges?" Second, "How do power surges damage electronics?"

Power surges

A power surge, also called transient voltage, is an increase in voltage well above the typical level in a flow of electricity. In the United States, the standard voltage is 120 volts. When voltage rises above 120 volts, equipment can be damaged. A surge protector helps prevent the surge from destroying your equipment.

If a power surge or spike is high enough, it can cause major damage to a machine. The effect is a bit like putting too much water pressure in a garden hose, which can cause the hose to burst.

This is similar to when too much electricity runs through a wire, which can cause the wire to burst. Technically, it heats up like the filament in a light bulb and burns, but you get the idea. Even if the voltage surge doesn't immediately destroy your machine, it may put extra strain on the components, wearing them down.

Surge protection

Surge protectors function by passing the electrical current from the wall outlet to a number of electronic devices plugged into the power strip. If voltage from the wall outlet surges or spikes, a surge protector will divert the extra electricity to the outlet's grounding wire.

Most surge protectors use a device called a metal oxide varistor, or MOV, to divert the extra voltage. An MOV is made of three parts: metal oxide material in the middle and two semiconductors joined to the power and grounding line.

When the voltage passing through is at correct levels, the MOV does nothing. When voltage surges and gets too high, the MOV will conduct much of the current to eliminate the extra voltage.

Besides using a MOV, surge protectors sometimes work using:

Gas Discharge Arrestor

Ionized Gas

Parallel Circuit Design

Series Circuit Design

Built-In Fuse

What causes a power surge?

In a lightning storm, you shouldn't rely on a surge protector. If lightning strikes near a power line, the electrical pressure can be boosted by millions of volts. This causes an immense power surge that will overpower most surge protectors. The best protection is to unplug devices around your home.

More commonly, the operation of high-power electrical devices, such as elevators, air conditioners, and refrigerators causes power surges. Such high-powered equipment requires a lot of energy to turn on or off components like compressors and motors. This creates sudden, quick demands for power, which disturbs the steady voltage flow in the electrical system.

Power surges can also come from faulty wiring, problems with a utility company's equipment, and downed power lines. The intricate system of transformers and lines that brings electricity from a power generator to our homes and offices is extremely complex. Many possible points of failure and other errors can cause an uneven power flow.

More information on surge protectors