1-2
Systems Connections
A regulator can regulate a single-phase circuit, or
one phase of a three-phase wye (star) or delta circuit.
Two regulators connected phase-to-phase in open-delta,
or three regulators connected phase-to-phase in closed-
delta, can regulate a three-phase, three-wire circuit.
When connected in wye, three regulators can regulate a
three-phase, four-wire multi-grounded wye circuit. Three
regulators should not be connected directly in wye on
three-phase, three-wire circuits because of the
probability of neutral shift, unless the neutral is
connected to the neutral of a wye-connected bank of
distribution transformers or to the substation transformer
secondary neutral. Typical connection diagrams are
illustrated in Figures 1-1 through 1-5.
WARNING: Connect the “S” bushing to the
source, the “L” bushing to the load, and the
“SL” bushing to neutral. To do otherwise may cause
excessively high or low voltage on the load side of the
regulator or cause severe damage to the regulator.
Figure 1-3.
Regulating a three-phase, three-wire circuit with
two regulators
Figure 1-5.
Regulating a three-phase, three-wire circuit with three regulators
NOTE: Individual switches are shown for the bypass and disconnect functions. However, a regulator-bypass-disconnect switch can be used in
each phase to perform the bypassing and disconnecting operations in sequence. Each of these switches replaces one bypass and two disconnect
switches shown in the diagrams.
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