Fig. 2,424.—General Electric direct current (form S) voltage regulator. It consists of a main control magnet, relay, condenser and reversing switch, as shown in the diagram fig. 2,428. This regulator cannot be used for compensation of line drop as the current coil is omitted; it is not a switchboard instrument, but is designed for inexpensive installations such as for regulating the voltage of motor generator sets when the current is taken from a trolley line or some other fluctuating source. The regulating outfit comprises, besides the regulator, one or more condenser sections according to field discharge, set of iron brackets when regulator cannot be mounted on front of switchboard, one compensating shunt, when it is desired to compensate for line drop. Field rheostats having sufficient resistance to reduce the voltage the proper amount must be used with voltage regulator installations. To prevent undue decay at the relay contacts, allow one section for each 15 kw. capacity of dynamo with laminated poles, and one for each 22 kw. capacity with solid steel poles.
Ques. What kind of magnetizing flux is produced by the primary windings?
Ans. A practically constant flux which varies in direction.
Ques. How is the secondary wound?
Ans. There is a separate winding for each phase.
Ques. Why is the voltage induced in the secondary constant?
Ans. Because of the constant magnetizing flux.
Ques. How is the line voltage varied by a polyphase regulator?