• Transient Voltages

Transient Voltages (also known as Surges and Spikes) are very short-duration, high voltage anomalies that damage electronic & electrical equipment. The momentary changes in voltage that occur over a period of time can be composed of one very short voltage peak (often less than 1 ms), to a much longer duration or a repeating transient that decays over multiple cycles or a mixture of both. Voltage transients normally last about 50 microseconds (50 millionth of a second) the ANSI C62.41-1991 which is the standard for transients in facilities operating under 600 Volts.

Technical definition
(ANSI std. 1100-1992) A sub-cycle disturbance in the AC waveform that is evidenced by a sharp brief discontinuity of the waveform. Transients may be of either polarity and may be of additive or subtractive energy to the nominal waveform.

> Learn more about Transient Voltage Characteristics


  • Sources of Transient Voltages

Common Internal Sources of Voltage Transients

  • Capacitor Bank Switching
  • Compressors
  • DC Drives
  • Electronic Ballast
  • Generators
  • High-Frequency Lighting Power Supplies
  • Inverters
  • Laser Printers
  • LED Lighting
  • Motor Controllers
  • PC Power Supply’s
  • Photocopiers
  • Power Supplies
  • Pumps
  • Standard Electric Motors
  • Temperature Controllers
  • VFD (Variable Frequency Drives)
  • Welders

  • How do Transients “Travel”

The common aspect of all these internally generated voltages is your electrical distribution system. Your facility wiring is designed to transmit electricity with the least impedance possible so that maximum efficiency is maintained. This same efficiency works to transfer the transients produced throughout your facility with minimal obstruction.

All of your panels are physically bonded together by multiple means. Transient activity “seen” at one panel is easily transmitted to all other panels within your system, dependent upon transient frequency and magnitude. You may even have transient activity you are unaware of even after you have “measured” your power quality.  This is because high-frequency transient activity must be measured near its source.  Many facility managers check power quality at the service entrance panel (because this is where the utility companies tend to do it for free).


  • How much damage / disruption do they cause?

Voltage transient activity is believed to account for 80% of all electrically-related downtime of which lightning accounts for at least 5% of all insurance claims.


  • Effects of Transient Activity

  • Electronic Equipment:
    • Electronic devices may operate erratically. Equipment could lock up or produce garbled results. These types of disruptions may be difficult to diagnose because improper specification and installation of transient voltage surge suppression equipment can actually INCREASE the incidents of failure as described above. Electronic devices may operate at decreased efficiencies. Damage is not readily seen and can result in early failure of affected devices. Unusually high frequency of failures in electronic power supplies are the most common symptom.
  • Integrated circuits:
    • Electronic chips may fail immediately or fail prematurely. Most of the time, the failure is attributed to “age of the equipment”. Modern electronic devices provided clean, filtered power should outlast the mechanical devices they control.
  • Motors:
    • Motors will run at higher temperatures when transient voltages are present. Transients can interrupt the normal timing of the motor and result in “micro-jogging”. This type of disruption produces motor vibration, noise, and excessive heat. Motor winding insulation is degraded and eventually fails. Motors can become degraded by transient activity to the point that they produce transients continually which accelerates the failure of other equipment that is commonly connected in the facility’s electrical distribution system. Transients produce hysteresis losses in motors that increase the amount of current necessary to operate the motor. Transients can cause early failures of electronic motor drives and controls.
  • Lighting:
    • Transient activity causes early failure of all types of lights. Fluorescent systems suffer early failure of ballasts, reduced operating efficiencies, and early bulb failures. One of the most common indicators of transient activity is the premature appearance of black “rings” at the ends of the tubes. Transients that are of sufficient magnitude will cause a sputtering of the anodes – when these sputters deposit on the insides of the tube – the result is the black “ends” commonly seen. Incandescent lights fail because of premature filament failures. The same hysteresis losses produced in motors are reproduced in transformers. The results of these losses include hotter operating temperatures, and increased current draws. Do you want to see a graphic illustration of the results of transient activity on fluorescent tubes? Look at the ends of your tubes, see those dark rings? Effective transient suppression will eliminate those rings and make your bulbs last 4 to 6 times longer.
  • Electrical Distribution Equipment:
    • The facility’s electrical distribution system is also affected by transient activity. Transients degrade the contacting surfaces of switches, disconnects, and circuit-breakers. Intense transient activity can produce “nuisance tripping” of breakers by heating the breaker and “fooling” it into reacting to a non-existent current demand. Electrical transformers are forced to operate inefficiently because of the hysteresis losses produced by transients and can run hotter than normal.

  • How to prevent damage caused by Transient Voltages?

Surge Protection Devices (SPD) mitigate transient voltages damage thereby extending the life of electrical and electronic equipment (*by up to three times). System-wide SPD implementation dramatically increases reliability / operational uptime. SPD transient voltage suppression is very cost effective, easy to install and provide immediate power grid protection for both internal and external derived transients.