In electrical engineering (this includes information technology), spikes are fast, short duration (from nano seconds up to about a second) electrical transients (usually in many hundreds to many thousands of volts) in voltage (voltage spikes), current (current spike), or transferred energy (energy spikes) in an electrical circuit.
Fast, short duration electrical transients (overvoltages) in the electric potential of a circuit are typically caused by
- lightning strikes
- power outages
- tripped circuit breakers
- short circuits
- power transitions in other large equipment on the same power line
- malfunctions caused by the power company
- electromagnetic pulses (EMP) with electromagnetic energy distributed typically up to the 100 kHz and 1 MHz frequency range.
- Inductive spikes
http://en.wikipedia.org/wiki/Voltage_spike, 4 December, 2008.
Surges are of longer duration than spikes, lasting for a few seconds to several minutes; and typically only over a range from 140 to a few hundred volts.
Users, and I.T. personnel have gotten lazy about the terminology over the years and typically are lumping surges and spikes under the term surge nowadays.
The thing is, simple surge protectors (your standard powerstrip type) basically dump excess power to the ground, and then either trip a breaker or burn out a fuse in the protector; breaking the circuit and keeping the dangerous level of power from reaching your system. Of course that causes your system to shut down.
Spikes are not protected by simple surge protectors as the jump in voltage is fast enough to get through the breaker/fuse before it trips, or is high enough to arc over the gap even if it burns out.
And simple surge protectors do nothing about dips or drops in power; which can be just a dangerous to your equipment (especially motors driving cooling fans).
Ideally, you want a solution that is a combination uninterrupted power supply, spike and surge protector, and line conditioner. The power supply kicks in to deliver adequate power during drops. The spike and surge protection works for both. And the line conditioner keeps you cycling at the necessary 50 or 60 cycles your system works best at.
