Quantcast Low Power Factor

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(a) Locate and repair or isolate the fault.
(b) Make a careful visual inspection for evidence of housing or bushing damage, or oil
(c) Close the recloser with a hookstick, keeping the hook in the operating ring
momentarily so that the recloser can be opened manually in case local trouble or failure becomes
evident. If no local trouble develops, and the recloser again locks out after going through its
proper sequence, it should not be reclosed again until the entire circuit on the load side has been
patrolled and cleared to all sectionalizing devices. Cold-Load Pickup. The inrush current experienced in closing a recloser after a
lockout operation may occasionally introduce some complications. The highest inrush current
can be from automatic starting motors or magnetizing current of transformers; however, these
types of inrush currents are normally short-lived (in the order of three to thirty cycles). Some
reclosers may operate on the instantaneous trip due to this inrush current, and may have to open
and automatically reclose until the sequence of operation comes to the time-delay trip before the
recloser will stay closed. Other reclosers, when reclosed after lockout, do not operate on the
instantaneous trip. They have a time-delay trip operation to lock out, which will normally
override the inrush current and pick up the load. Careful observation by the operator may
indicate whether failure to hold onto the load is caused by a fault or by a momentary overload.
Instant, and perhaps violent, action would indicate a fault, whereas some delay might mean
overload due to inrush current. In the latter case, sectionalizing to drop part of the load, rather
than a patrol, is necessary.
3.7 POWER CAPACITORS. Power capacitors are used in distribution systems to supply
reactive volt-amperes (Vars) to the system. When applied to a system or circuit having a lagging
power factor, several beneficial results are obtained. These results include power factor increase,
voltage increase, system loss reduction, and release of electric system capacity.
3.7.1 Low Power Factor. A low system power factor can be increased by adding corrective
equipment to the system. There are many devices used for power factor correction, including
synchronous motors and power factor correction capacitors. Synchronous Motors. Any synchronous motor may be used for power factor
correction by overexcitation. Power Factor Correction Capacitors. For general use, the most practical and
economical power factor correction device is the capacitor. Capacitors are used at power stations
where an elaborate and expensive synchronous condenser installation is not justified. The
following paragraphs deal exclusively with power capacitors.


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