GUIDE-VALVE 1220447 - Caterpillar

The transfer mechanism must be tested with all power supplies turned OFF. Use a volt-ohm-meter (VOM) for the tests. During the tests the main contacts will be manually actuated to (a) tripped or NEUTRAL position, (b) STANDBY position, and (c) NORMAL position.
: ALL Power must be turned OFF to the transfer switch before attempting manual operation and/or tests. Extremely dangerous - possibly lethal - electrical shock could occur.
In the tests that follow, the actual resistance reading is not given. A specific resistance is not important. Either a small resistance or infinity should be indicated, as specified in the specific test.Tests With Main Contacts At NEUTRAL
Transfer Mechanism Terminal StripTurn OFF all power voltage supplies to the transfer switch. Manually actuate the main contacts to their NEUTRAL (Tripped) position. (See functional tests, manual operation for instructions to manually actuate the transfer mechanism) Verify that the word "OFF" is visible in both power source display windows. To completely check the transfer mechanism when in the NEUTRAL position, perform all the following tests with an ohmmeter.With the main contacts tripped (in NEUTRAL position), connect ohmmeter test probes across transfer mechanism terminals as follows.Closing Coil (C) Continuity And Diode Test
1. Positive test probe at A1, Negative at A2: Meter should indicate a small resistance.2. Positive test probe at A2, Negative at A1: Meter should indicate a small resistance.Selective Coil (SC) Continuity And Diode Test
1. Positive test probe at B1, Negative at B2: Meter should indicate a small resistance.2. Positive test probe at B2, Negative at B1: Meter should indicate a small resistance.Trip Coil Switch (ATS1 and ATS2) Test
1. Positive test probe at AT1, Negative at AT2: Meter