7
1.2
Changing Transformer Taps
NOTE: This procedure refers
only
to A77 battery chargers that are
rated for 6 to 25 ADC
. All other A77
battery chargers do not include transformer taps. (Special chargers can be ordered upon request.)
Before wiring AC power to the A77, check the wiring of the power transformer PT, to be sure it is connected for
the correct AC input voltage. The A77 accepts standard input voltages of 120, 208 or 240 VAC by changing the
connections to the input terminals. No other changes are required.
NOTE: The A77 is wired at the factory for 240 VAC, except on special request.
Before changing the PT taps, be sure that AC supply and DC loads to the A77 are turned off and locked out.
Verify that no voltage is present by using a voltmeter at all input and output terminals. Turning off the AC and
DC circuit breakers on the A77
does NOT eliminate live voltages inside the enclosure. Also de-energize any
external wiring to the alarm relay contacts.
Verify that all voltages within the enclosure are de-energized and locked out. Change the connections to the
input terminals as shown in the table and figure below.
NOTE: An A77 battery charger rated for 480 VAC or 600 VAC input uses a special transformer that has no taps.
The 480 VAC and 600 VAC transformers cannot be used for any other input voltage.
Changing Transformer Taps Procedure
Before beginning any work inside the charger enclosure ensure that all incoming AC supply and DC load wires
are de-energized. Verify that no voltage is present inside the enclosure by using a voltmeter at all input and
output terminals.
For 120 VAC Input Voltage:
1.
Connect wire marked
A
to terminal
8
2.
Connect wire marked
B
to terminal
10
3.
Connect wire marked
C
to terminal
6
Note that
AC Line
connects to terminal
1
Note that
Neutral
connects to terminal
3
For 208 VAC Input Voltage:
1.
Connect wire marked
A
to terminal
9
2.
Connect wire marked
B
to terminal
8
3.
Connect wire marked
C
to terminal
5
Note that
AC Line 1
connects to terminal
1
Note that
AC Line 2
connects to terminal
2
For 240 VAC Input Voltage:
4.
Connect wire marked
A
to terminal
10
5.
Connect wire marked
B
to terminal
8
6.
Connect wire marked
C
to terminal
5
Note that
AC Line 1
connects to terminal
1
Note that
AC Line 2
connects to terminal
2
ACin1
ACin2
A
B
C
INPUT
VAC
120
1 (L1)
3 (N)
8 10
6
208
1 (L1) 2 (L2) 9
8
5
240
1 (L1) 2 (L2) 10
8
5
Table 3 - Input Terminal Connections
Figure 6 - Input Terminals
Connection Schematic
Summary of Contents for A77
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