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 TABLE 3-2
OVERVOLTAGE LIMITS
Multiplying Factor Times
Duration
Rated rms Voltage
1/2 cycle
4.8
1 cycle
4.2
6 cycles
3.0
15 cycles
2.6
1 second
2.2
15 seconds
1.8
1 minute
1.7
5 minutes
1.5
30 minutes
1.35
occasionally be encountered. Blowing of fuses or high-temperature operation may indicate an
overload condition. Capacitors and auxiliary devices are normally designed to carry at least 135
percent rated kVar maximum including kVar due to resonance. If the capacitor kVar exceeds
135 percent of its rating, it should be reported.
3.7.10 Personnel Protection. Operators, working on capacitors or other equipment to which
capacitors are connected, should wear rubber gloves and safety glasses or a face shield for
protection from arcing. Such work includes opening or closing switches or fused cutouts, testing,
short-circuiting terminals, and grounding capacitor terminals to the case or rack. When the area
around capacitors and other electrical apparatus is wet, wood platforms, insulated stools, or
rubber boots should be used. After disconnecting a capacitor, and before any work is attempted,
the operator should wait at least five minutes to allow time for the resistors to drain off the major
portion of the residual charge. The capacitors should then be short-circuited several times or
until no arc is observed. An insulated jumper should be used for short-circuiting. Each terminal
should then be grounded. The short-circuiting device and ground connection should be left in
place until the work is finished, but must be removed from the capacitor before the unit is
reenergized.
3.8 DISTRIBUTION SUBSTATION. Each distribution substation normally serves a single load
area. At the distribution substation the subtransmission voltage is reduced for general
distribution throughout the area. The substation consists of one or more power-transformer
banks together with the necessary voltage regulating equipment, buses, and switchgear.
3-55
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