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Surge
Protection Device (SPD) Specification Glossary
Maximum
Operating Voltage (MCOV):
Maximum allowable continuous sinusoidal voltage (RMS)
at 50-60hz.
Measured Limiting (Let-Through) Voltage:
The maximum magnitude of voltage that is measured across
the terminals of the SPD during the application of impulses
of specified waveshape and amplitude.
Input
Power Frequency:
Frequency range in which the SPD operates without causing
damage to the SPD or equipment, or interference with the
power signal. Applicable to AC circuits.
Peak
Surge Current:
Maximum current allowed for a single 8x20 microsecond
waveform, us impulse with continuous voltage applied.
The higher the number, the more surge current the unit
will dissipate.
Filter
Frequency Range:
The range of frequency in which a filter operates. The
3db points on the low and high ends of the frequency scale
usually dictate this.
Frequency
(Noise) Attenuation:
The range of attenuation for a given frequency range.
A larger negative number indicates a greater attenuation.
Energy:
Maximum allowable energy for a single impulse on an 8x20
us current waveform. Indicative of the maximum amount
of energy that a suppressor can dissipate. This energy
is transitory and is dependent upon three (3) variables:
1. Voltage, 2. Current, and time. Any variation of the
three will effect this figure.
Response
Time:
The time in which a suppression device responds to a transient.
Protection
Modes:
Protection mode indicates the suppressor's ability to
protect different paths of transient activity. Normal
mode = line to ground and /or neutral to ground. Common
mode = line to line.
Dynamic Let-Through Voltage Test:
Test conducted with normal operating voltage applied.
Static
Let-Through Voltage Test:
Test conducted with no normal operating voltage applied;
e.g.: neutral-to-ground, which has no voltage normally
applied.
Positive
Or Negative Polarity:
Indicates the direction in which the surge occurs.
Transient
Phase Angle:
The point on the sine wave at which a transient occurs.
IEEE states that transients can occur at any phase angle.
It is important to be able to see the SPD'S response to
transients at varying phase angles.
Peak Transient Voltage:
The peak transient voltage which is applied to the SPD
under test according to ANSI/IEEE C62.41 1980, section
4.1.
Surge
Transient Amperage:
IEEE has developed waveform guidelines for testing. In
this guideline, discharge currents (surge currents) are
given as 200A, 500A, 3000A. These values when combined
with the appropriate transient waveshape represent possible
transient activity according to ANSI/IEEE C62.4 1 - 1980.
Listings:
Statement of independent laboratory testing, for safety
and/or performance.
References used for above definitions:
ANSI/IEEE C62.4 1-1980
UL Second Edition 1449 (REV Feb 9, 2007)
Dictionary of Electronics
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