3.3.7 Parallel Operation of Step Regulators. Special adaptations make it possible to operate
step regulators in parallel, however, certain restrictions are imposed by each method. The choice
of a method is dependent upon such factors as circuit impedances, proximity of units, and the
types of equipment being paralleled. This is to prevent off-step operation, which could lead to
excessive circulating current between regulators.
3.3.8 Bypassing Single-Phase Voltage Regulators. In order to provide continuity of service
and to prevent injury to the regulator, special facilities and procedures are necessary for
switching regulators on and off a line. The following are general procedures; individual
manufacturer's instructions should be followed.
220.127.116.11 Disconnecting Regulator. Referring to Figure 3-10 (Bypass Switching
Arrangement for Single-Phase Voltage Regulator), the sequence of operation for disconnecting a
voltage regulator is summarized as follows:
(a) Place regulator control on manual and adjust to neutral position.
(b) Open the control power switch.
(c) Close switch D shorting series winding.
(d) Open switch C and then B.
(e) Open switch A, if used. This switch is required only when terminal S2 - L2 is
not connected to the neutral or ground wire.
18.104.22.168 Connecting Regulator. Referring to Figure 3-10, the sequence of operation for
connecting a voltage regulator is summarized as follows:
(a) Verify that the regulator control switch is in the manual position and that the
regulator is in the neutral position.
(b) Close switch A, if used.
(c) Close switch B and switch C.
(d) Open switch D.
(e) Close the control power switch.
(f) Turn control switch from manual to automatic.