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What's the difference between a surge and a spike in voltage?

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1. Steady-State Voltage - Steady-state rms voltage values are those that stay constant for 10 seconds or longer. 2. Nominal or Normal Voltage - The normal planned voltage for a system. For most equipment this is 110-125VAC.
3. Power Failure - A power failure is a zero voltage condition lasting for more than one cycle (1/60 second) on any one of the three phases being used.
4. Blackout - A total power failure lasting several seconds to hours or more.
5. Brownout - A planned and generally announced city or regional-wide reduction by the utility in the steady-state voltage possible due to heavy electrical consumption.
6. Undervoltage - A continuous reduction in the steady-state voltage below the normal voltage. Similar to brownout but this term is generally used to refer to unplanned reductions or localized problems within the building or circuit.
7. Overvoltage - A continuous exceeding of the normal voltage.
8. Sag - Sags are cycle-to-cycle decreases in the power line voltage on any one of the three phases below the normal value. The lasting time of a sag is its duration in the number of cycles of the 60HZ line frequency that the disturbance is below, and returns to the normal level.
9. Dip - Dips are very short (but visible in incandescent light bulbs) decreases in the normal power line voltage. These are similar to sags but are noticeably faster. A dip is a fast sag.
10. Surge - Surges are cycle-to-cycle increases in the power line rms voltage on any of the three phases above the normal voltage. Lasting time for surges is measured the same way as are sags.
11. Swell - Swells are longer term multi-cycle slow rising surges lasting from a few seconds to several minutes.
12. Impulse - An impulse is a very short term disturbance up or down superimposed on the AC sine wave that typically lasts between 0.5 and 100 microseconds. In-phase going impulses which increase the instantaneous voltage are called spikes. Out-of-phase impulses which decrease the instantaneous voltage are called notches.
13. Spike - An over voltage impulse ranging from 400V to 5600V or more which is superimposed on top of the AC sine wave. These, when over 600V, are potentially very damaging disturbances.
14. Notch - An under voltage impulse similar to a spike but of reverse polarity to the instantaneous value of the AC sine wave so as to take a momentary notch out of the sine wave. Notches are typically too fast to see. These typically last as long as spikes but can be up to several milliseconds. In addition, spikes and notches usually come in pairs or in an oscillating series. For every notch there is usually an immediately following spike due to power line inductances and capacitances.
15. Transient - A transient is any short-term non-normal event on the power line. All power line disturbances are transient by definition.
16. EMI - Broad spectrum electromagnetic noise interference either conducted on the power line directly from the source or radiated to the power line then conducted to the susceptible equipment.
17. RFI - Electromagnetic noise interference in the radio spectrum.
18. TVI - Electromagnetic noise interference in the television spectrum.
19. EMP - A very large and very fast rising electromagnetic pulse caused by catastrophic events such as lightning or nuclear detonation.
20. Harmonic - Harmonics are sinusoidal currents and voltages with frequencies that are integral multiples of the fundamental power line frequency. Harmonics distort the normal sine wave.
21. Normal Or Differential Mode - Events which occur across the normal current carrying wires of the power line-hot wire to neutral wire. Also called the transverse or metallic mode.
22. Common Mode - Events which occur from the current carrying wires, hot and neutral, relative to the safety wire-ground.
23. MOV - Metal Oxide Varistor. A voltage dependent resistor. A low cost but very effective protection device. They can handle large surges and switch in 1 to 5 nanoseconds. It works by absorbing voltage surges and spike impulses. They are most effective when used in groups of three to provide both differential mode and common mode protection.
24. Silicon Avalanche Zener Diodes - A solid-state junction device. These devices are very fast acting but have low energy handling capability. Switching speed is in picoseconds. They work by shunting the surge or spike impulse around the protected circuit.
25. Gas Discharge Tube - A calibrated spark gap in a gas filled chamber. These devices are relatively slow, activating in microseconds but can handle very large surges. They work by shunting the surge or spike impulse around the protected circuit.
26. EMI/RFI Filter - A circuit or device containing series inductive (load-bearing) and parallel capacitive (nonload-bearing) components which provides a low impedance path around the protected circuit for high frequency noise. Filters also attenuate impulses since a Fourier's Analysis of a spike will reveal it is composed of high- frequency waveforms. Filters and surge suppressors when used together thus act synergistically.
27. UPS - An Uninterruptible Power System which provides a steady source of electric energy to a piece of equipment.
28. Continuous UPS - A UPS system for which the load is continually drawing power through the batteries and inverter and never directly from the normal AC power line.
29. Standby UPS - A UPS system which normally connects your equipment to the normal AC power line with the batteries and inverter in standby mode. When the power line is weak or fails it transfers the load to the batteries and inverter without any load malfunction and without any user action. When the power line returns to normal the load is automatically retransferred back to the AC power line.
30. Voltage Surge Suppressor - A fast acting circuit or device containing MOVs, Silicon Avalanche Diodes, Gas Discharge Tubes, or other components which suppresses voltage surges and spikes to a safe level. The energy in the surge or spike is either dissipated as heat in the protection components or is diverted to earth ground by the circuitry.
31. Voltage Regulating Transformer - A continuous acting transformer, usually ferro-resonant, which instantaneously regulates the output voltage to normal levels despite wide swings in the input voltage.
32. Voltage Stabilizer - A switching device which selects appropriate windings of a transformer to maintain normal output voltage levels despite wide swings in the input voltage. Switching occurs after the power is non-normal for a few seconds. This device is commonly confused with a voltage regulating transformer but they differ greatly in response time. Stabilizers are generally too slow to protect solid-state devices.
33. Power Line Conditioner - A PLC is a combination of a voltage regulating transformer with a super isolation transformer which provides smooth, regulated, noise free, AC voltage with no ohmic connection between input and output. A PLC will solve most problems other than complete power failure.

Posted on Nov 11, 2014



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A spike is an increase in voltage for 1-2 nanoseconds.
A surge is the increase lasts 3+ nanoseconds.

Posted on Feb 05, 2014


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