Guardian 4389 Repair Manual page 79

DC CONTROL
• Utility source voltage is available to transfer switch Terminal Lugs N1/N2. With the transfer switch main con-
tacts at their "Utility" side, this source voltage is available to Terminal Lugs T1/T2 and to the "Load" circuits.
• Utility voltage is delivered to the primary winding of a sensing transformer (TX), via transfer switch Wires
N1/N2, fuses F1/F2, connected wiring, and Control Panel UTILITY 1 and UTILITY 2 terminals. A resultant volt-
age (about 16 volts AC) is induced into the transformer secondary windings and then delivered to the circuit
board via Wires 224/225. The circuit board uses this reduced utility voltage as sensing voltage. Wires
224A/225A supply 16 VAC to the battery charger.
• Battery output is delivered to the circuit board with the AUTO-OFF-MANUAL switch (SW1) set to AUTO, as
shown.
11
22
TX
225A N2
56VA
224A
225
1VA
224 N1
+
-
0 0 12VDC ACCESSORY SOCKET
15B
13
13
0 0
F2
15B
0
15A
17
23
194
13
0
239
14
0
15
17 15 SCR
56
18
0
0 0
17
15
0 0
18
C1-5
PART 4
C2-6
C2-5
N2
N1
17
F1
15
15
15 15A
15 15
15
23
194
239
14
15
13
C2-1
16 16
14
C1-1
SC FS
0 0
0
G
IM1
D
SP1
18
IM2
D
SP2
194 23 11 22
22
SW1
239
N
11
RED
SC
BATTERY
SM
12V
BLACK
CUSTOMER
SUPPLIED
G G
Figure 1. Circuit Condition - Utility Source Voltage
SECTION 4.2
OPERATIONAL ANALYSIS
240VAC
N1
UTILITY
N2
INPUT
12Vdc
23
TRANSFER
RELAY
194
COIL
22
N
33
120V
POWER
120V
WINDING
(STATOR)
44
CB1
11
11
N N
240V
CB3
L
N L
G G
EXTERNAL
GFCI
OUTLET
23
TR
194
CUSTOMER
CONNECTIONS
Available
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