CA01065E_Catalog 70

ARRESTERS

Technical Terms

Phase-to-Phase clearance: The phase to phase spacing required between metal parts at 1800m in order to prevent flash over. Reference Current (Iref): The peak value of the resistive component of a power-frequency current high enough to make the effects of stray capacitance of the arrester negligible. Reference Voltage (Vref): The lowest peak value independent of polarity of power-frequency voltage, divided by the square root of 2, required to produce a resistive component of current equal to the reference current of the arrester. Routine Tests: Tests made by the manufacturer on every device to verify that the product meets the design specifications. Some tests are required by IEEE and IEC standards, while other tests are dictated by Hubbell Engineering. Steep front: A nominal discharge current impulse with a front time of 0.5 microseconds. Also referred to as front-of-wave (FOW)

Strike distance: The distance in air of a line between two conductors on the arrester.

Switching Surge: The surge current when a system changes configuration.

TOV (Temporary Over Voltage): A power frequency (48 – 62 Hz) voltage in excess of normal line-to-ground voltage. A TOV is typically system generated. The magnitude and duration are a function of the power system parameters. U C : The designated root-mean-square (rms) value of power-frequency voltage that may be applied continuously between the terminals of the arrester. Watts Loss: Power loss through an arrester while energized. Routine tests are conducted at 1.25 x MCOV. Wet Withstand: Maximum power frequency voltage that the arrester can withstand in wet conditions without causing an external flashover of the housing.

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