Guardian 4389 Repair Manual page 87

DC CONTROL
ground. The transfer relay then energizes and its normally open contacts close.
• Standby power is now delivered to the standby closing coil (C2), via Wires E1 /E2, the normally open transfer
relay contacts, Wire 205, limit switch XB1, Wire B, and a bridge rectifier. The standby closing coil energizes
and the main current carrying contacts of the transfer switch are actuated to their STANDBY source side.
• As the main contacts move to their STANDBY source side, a mechanical interlock actuates limit switch XB1 to
its open position and limit switch XA1 to its "Utility" side position. When XB1 opens, standby closing coil C2 3
de-energizes.
• Standby power is delivered to the LOAD terminals (T1/T2) of the transfer switch.
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 5. Circuit Condition - Initial Transfer to
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
Standby
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