basis. Voltage control is used where objectionable

circuit must be capable of serving the load over

voltage changes occur with varying voltages. Cur-

the required distance without exceeding the allow-

rent control is used when loads change, but voltage

able voltage drop. The number of circuits and

is well regulated or load power factor remains

conductor sizes will be determined by an economic

substantially constant. Current control is effective

evaluation of the possible configurations including

also when power factor varies in a predictable

construction requirements (span lengths, pole

manner with the load. Kilovar control is used when

heights, pole classes) for conductor capacities at

load voltage is regulated, but power factor varies in

the primary distribution voltage and higher volt-

an unpredictable manner to corresponding load

ages.

variations. More sophisticated current and voltage

(1) *Quick check values. *Table 5-1 has been

control than that covered by IEEE Std 18 can be

prepared to allow a quick check of the capacities of

provided, and manufacturers should be consulted

three-phase medium-voltage circuits at 0.90 power

for application and specification information.

factor by giving the approximate kilovolt-ampere-

mile loading for a three percent voltage drop. For

voltages not given, the use of a factor of the

square of the ratio of the desired voltage divided

cuits will be determined on the basis that each

by the known voltage times the megavolt-ampere-

Integrated Publishing, Inc. |