 |
High voltage may be present. The power source must be disconnected before working on equipment. Failure to disconnect the power source could result in injury or death. |
The inspection should not be started until the system is locked out. In order to lock out the transfer switch, turn the "AUTO/INHIBIT" switch to the INHIBIT position. Then, put the external disconnect switch for the normal power source in the OFF position and lock out the disconnect switch. Then, put the external disconnect switch for the emergency power source in the OFF position, and lock out the disconnect switch.
The transfer switch should be inspected and preventive maintenance should be performed on a yearly basis. The transfer switch should be inspected for any accumulation of dust, dirt, or moisture. The switch should be cleaned by a vacuum cleaner or by wiping the switch with a dry cloth or a soft brush. DO NOT use compressed air. The use of a vacuum is recommended.
Note: If compressed air is used, debris could lodge in the switch.
The Electrical connections should be inspected. The screw terminals for external power connections should be checked in order to make sure that the screws are tightened to the proper torque values. The proper torque values are shown in table 1. The lugs should be checked in order to make sure that the lugs are tightened to the proper torque values. The proper torque values are shown in table 2. If the unit has bus bars, the bus bars should be checked in order to make sure that the bolts are tightened to the proper torque values. The proper torque values are shown in table 3.
| Screw Terminals for External Power Connections | ||||
|---|---|---|---|---|
| Switch Size in Amp. | Normal, Emergency, and Load Terminals | Neutral Bar (1) | ||
| Cable Per Pole | Range of Wire Sizes | No. of Cables | Range of Wire Sizes | |
| 40 | 1 | #8 to 1/0 AWG | 3 | #8 to 1/0 AWG |
| 80 | 1 | #8 to 1/0 AWG | 3 | #8 to 1/0 AWG |
| 100 | 1 | #8 to 1/0 AWG | 3 | #8 to 1/0 AWG |
| 150 | 1 | #8 to 3/0 AWG | 3 | #8 AWG to 300 MCM |
| 200 | 1 | #8 to 3/0 AWG | 3 | #8 AWG to 300 MCM |
| 225, 250 (2) | 1 | #6 AWG to 250 MCM | 3 | #6 AWG to 300 MCM |
| 260, 300 (2), 400 | 1 | #4 AWG to 600 MCM | 3 | #4 AWG to 300 MCM |
| 600 | 2 | #2 AWG to 600 MCM | 8 | #2 AWG to 600 MCM |
| 800 1000 1200 |
4 | #2 AWG to 600 MCM | 12 | #2 AWG to 600 MCM |
| 1600 2000 3000 4000 |
All of the terminals are located in the rear of the switch and the terminals are arranged for bus bar connections. | |||
| ( 1 ) | A Neutral Bar is not always required. |
| ( 2 ) | IEC Ratings Only |
| Tightening Torque for Lugs | ||
|---|---|---|
| Socket Size Across Flats | Torque | |
| N·m (lb in) | lb ft | |
| 1/8 | 5.1 (45) |
4 |
| 5/32 | 11.3 (100) |
8 |
| 3/16 | 13.6 (120) |
10 |
| 7/32 | 16.9 (150) |
12 |
| 1/4 | 22.6 (200) |
17 |
| 5/16 | 31.1 (275) |
23 |
| 3/8 | 42.4 (375) |
31 |
| 1/2 | 56.5 (500) |
42 |
| 9/16 | 67.8 (600) |
50 |
| Tightening Torque for Bus Bars | ||
|---|---|---|
| Bolt Size | Bolt Torque (Grade 5) | |
| N·m (lb in) | lb ft | |
| 1/4-20 | 8.1 (72) |
6 |
| 5/16-18 | 14.9 (132) |
11 |
| 3/8-16 | 33.9 (300) |
25 |
| 1/2-13 | 81.3 (720) |
60 |
The transfer switch should also be lubricated yearly using Lubriplate 105. For information about lubricating the switch, see Maintenance, "Transfer Mechanism - Lubricate".
Once the inspection is completed, the system can be energized. In order to energize the system, unlock the external disconnect switch for the normal power source. Put the disconnect switch in the ON position. Unlock the external disconnect switch for the emergency power source. Put the disconnect switch in the ON position. Finally, turn the "AUTO/INHIBIT" switch to the AUTO position.