3-3
a.
General
.
The regulator must be connected to the generator system as instructed in this section
and as shown in the basic interconnection diagrams (Figures 3-4 and 3-5). Number 16 gauge wire
(or larger) should be used for all connections to the regulator.
b.
Regulator Sensing (Terminals El, E2, and E3)
.
(1) The voltage regulator(s) contain an internal sensing transformer(s) T1 (T2) provided with taps for
various input sensing voltages. These sensing voltages are: 120, 208, 240, 416, 480, and 600 Vac
(refer to Figure 3-7).
The model number of the unit designates single-phase (T1) or three-phase
(T1 and T2) sensing. For operation with generator voltages above 600 Vac, a potential
transformers(s) must be used to supply the regulator sensing voltage. The regulator sensing circuit
load is less than 10 VA and correct polarity must be maintained to the regulator sensing input.
(2) On single-phase sensing models, the voltage sensing leads are connected to terminals E1 and
E3. For three-phase sensing, terminals E1, E2 and E3 are used. For precise voltage regulation, the
sensing leads should be connected as close as possible to the point where regulation is desired.
The regulator regulates the voltage that is applied to its sensing terminals. Therefore, it cannot
correct for voltage drop in leads that may occur at points other than where the regulator sensing
leads are connected. The leads that supply regulator sensing should not be used to supply power to
any other equipment or to the regulator power stage (terminals 3 and 4).
(3) SR4A & SR8A Voltage Regulators are factory preset for 120 Vac sensing voltage. If the
sensing voltage needs to be changed for your installation, perform the following steps.
Step 1
. Remove the cover if applicable.
Step 2
. Remove 9 hex screws.
Step 3.
Remove the printed circuit board without disconnecting the wires.
Step 4.
Locate transformer(s) T1 for single-phase sensing units (T1 and T2 for three-
phase sensing units). These transformers are equipped with Faston connectors
for changing sensing taps.
Step 5.
For single-phase sensing units, move the wire that is factory connected to T1-
120
terminal to the T1 terminal labeled with the desired sensing voltage.
Step 6.
For three-phase sensing units, move the wire that is factory connected to T1-
120
terminal to the T1 terminal labeled with the desired sensing voltage. Also, move
the wire from T2-
120
terminal to the T2 terminal labeled with the desired sensing
voltage.
(4) If the generator is to be operated in parallel with other generators, the phase relationship of
sensing voltage and the paralleling current transformer is very important. (See paragraph 3-3 for
further information.)
WARNING
The SR4A & SR8A Voltage Regulators are shipped factory
preset for 120 Vac sensing.
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