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More Surge Protector (surge protection) Information

Surge protectors are the primary defense you have to protect your sensitive electronic, computer, and stereo equipment from electrical surges or electrical spikes caused primarily by your power company, storms, and by internal electrical fluctuations within your home or office building. Internal causes can occur whenever equipment in a building is suddenly energized, like an elevator or air conditioning compressor; at home it can be when the refrigerator starts or washing machine changes cycles. These electrical surges or spikes usually only last for a short time, often less than a full electrical cycle which is 1/60 of a second, but over time repeated electrical spikes or power surges have a cumulative effect and will work to deteriorate electronic components which can eventually fail.

Surge protectors can be built with one or more of the following electronic components:

  • A fuse burns out or circuit breaker trips when excessive power is being consumed and fed to a device. These can protect both from surges caused by the device itself and from external surges that last long enough.

  • An iron poor transformer can transmit AC power similar to a normal iron core transformer (although less efficiently), but will be unable to transmit sudden surges that saturate the small iron core.

  • A MOV is a small device that will short out when presented with a sufficiently high voltage, hopefully passing the surge to ground through the MOV rather than through the protected device. Unfortunately, these devices tend to self destruct (and are therefore one-shot devices) with sufficiently strong surges. Many cheap surge protectors only have MOV's, and probably will not survive even a single lightning strike.

  • A zener diode is a small diode designed to protect against normal spikes in a circuit, especially motor controller circuits. These are sometimes paired as a transient voltage suppression diode.

  • A gas discharge tube is used much like a MOV, except that it relies on a trapped gas to become ionized to pass the voltage. This has the advantage of being able to pass much more power without self destructing, but with the disadvantage of reacting to the high voltage more slowly.

  • An Uninterruptible power supply (in addition to other surge protection devices listed above) typically passes external power past the unit's battery, which will absorb spikes much like a capacitor in parallel acts as a low pass filter. (This also keeps the battery charged, and in the event of a failure, the battery can continue to supply power without any interruption otherwise needed to switch it in.) Typically these are the best ones, but are also more expensive.

Voltage spikes are fast, short duration surges (overvoltages) in the electric potential in a given circuit. These are typically caused by lightning strikes, although power outages, tripped circuit breakers, short circuits, and power transitions in other large equipment on the same power line, and malfunctions caused by the power company can also cause them. While technically, the pulse produced by a nuclear explosion detonation produces a voltage spike, these rare events are commonly referred to as an electromagnetic pulse (EMP). The effect of a voltage spike is to produce a temporary increase in current flow. For sensitive electronics this can cause excessive current flow. In /semiconductor junctions, the voltage may exceed the reverse breakdown potential, thus destroying or severely weakening the device. A transient voltage suppression diode, transil, varistor, or a range of other overvoltage protective devices can be used to minimize this damage.
While generally referred to as a voltage spike, the phenomenon in question is actually a power spike, in that it is measured not in volts but in joules. The root cause is the rapid buildup and decay of a magnetic field, which will induce whatever voltage on the lines as is necessary to pass the given quantity of energy. Most equipment damage from surges and spikes can be prevented by the use of surge protection equipment.

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