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SAFETY FOR LIFE
Abnormal output readings at TB1 indicate a malfunctioning control. This procedure describes the terminal functions under manual direction and suggests areas for investigation.
1.Terminals 11 and 21 provide the power to charge the springs in the switch actuator and are constantly energized. If terminals 11 and 21 are not energized, the transfer bus is not energized.
A.Make sure that either phase B of the preferred source or phase Y of the alternate source is ener- gized. These phases supply the transfer bus. Measure beyond the fuses.
B.Relays R7 and R11 control power to the transfer bus. Relay R7 picks up when phase Y is ener- gized; Relay R11 picks up if phase B is energized and phase Y is deenergized.
2.Terminals 15 and 25 provide 120 Vac closing power (15 closes Source I switch, and 25 closes Source II switch). Terminals 13 and 23 provide 120 Vac open- ing power (13 opens Source I switch and 23 opens Source II switch).
A.Terminals 13, 23, 15 and 25 are energized from the transfer bus through the MANUAL OPER. switches, S1 and S2.
(1)If the control is equipped with the fault block accessory, normally closed contacts of the fault block relay (RY1) are connected between tabs FP and FR of the relay tie board to complete the circuit to terminal 15 and between tabs FS and FT to complete the circuit to terminal 25.
(2)If the control does not use the fault block accessory, jumpers are provided between tabs FP and FR and FS and FT of the relay tie board to complete the closing power circuits to the transfer switches.
3.Terminals 14 and 24 are grounded by an “a” contact (N.O.) in the H.V. transfer switches to energize relays R4 and R5 respectively during the “opening” half of a parallel return transfer.
The control may operate properly by manual direction but malfunction in its automatic mode. The automatic section responds to the positions of R2 and R6 in conjunction with the selected operating mode as set on S4, the SOURCE PREFERENCE and RETURN MODE switch. Its output is the
1.R2 is energized from phase A of Source I through N.O. contacts of R9 in phase B and R10 in phase C. The action of R2 can be observed through its trans- parent cover and can be checked electrically across tabs 31 and 32 on the relay tie board which connect to a N.C. contact of the relay.
2.R6 is similarly energized from phase X of Source II through R7 in phase Y, and R8 in phase Z. Tabs 41 and 42 connect to a N.C. contact of R6.
3.Operation of the appropriate time delay relay can be checked by verifying that the LED timer is illuminated.
4.The
5.With the control in an automatic mode of operation, the position of the latching relay can be determined at the Latching Relay Test jacks (T1, T2, T3) on the front panel of the control.
A.When 120 Vac is present between T1 and T3, the relay is in the “latched” position and the control seeks to connect the load to Source I.
B.When 120 Vac is present between T2 and T3, the relay is in the “reset” position and the control seeks to connect the load to Source II.
C.If the latching relay assumes the expected position after the proper time delay, the automatic section of the control is functioning properly.
4.Terminals 16 and 26 are energized (120 Vac) on the “closing” half of a
TABLE 6
Voltage Readings on TB1
|
| Voltage to Ground |
| ||
|
| MANUAL OPER. | MANUAL OPER. | ||
Term |
| SOURCE I | SOURCE II | ||
on |
| Switch (S1) | Switch (S2) | ||
TB1 | Quiescent | Close | Open | Close | Open |
11 | 120 Vac | 120 Vac | 120 Vac | 120 Vac | 120 Vac |
15 | 170 Vdc* | 120 Vac | 170 Vdc* | 170 Vdc* | 170 Vdc* |
14 | 170 Vdc* | 170 Vdc* | 170 Vdc* | 170 Vdc* | 170 Vdc* |
13 | 0 | 0 | 120 Vac | 0 | 0 |
16 | 0 | 0 | 0 | 0 | 0 |
26 | 0 | 0 | 0 | 0 | 0 |
23 | 0 | 0 | 0 | 0 | 120 Vac |
24 | 170 Vdc* | 170 Vdc* | 170 Vdc* | 170 Vdc* | 170 Vdc* |
25 | 170 Vdc* | 170 Vdc* | 170 Vdc* | 120 Vac | 170 Vdc* |
21 | 120 Vac | 120 Vac | 120 Vac | 120 Vac | 120 Vac |
|
|
|
|
|
|
*Rectified 120 Vac impressed on capacitor. Drops to 0 if LAMP TEST switch (S6) is depressed.
23