Product Manual

4 Troubleshooting

4.1 Introduction

This section describes troubleshooting issues, as well as the sequence of events for transfer switch

operations that do not include a controller.

4.2 Troubleshooting Procedures for Experienced

Service Personnel

This section describes a typical transfer switch sequence of events, and provides detailed troubleshooting

procedures for experienced service personnel. The troubleshooting procedures use conditional

schematics and symptoms to diagnose all possible problems.

WARNING

Improper operation of the generator set presents a hazard that can cause severe personal injury

or death. Observe all safety precautions in your generator set manuals.

WARNING

AC power within the cabinet and the rear side of the cabinet door presents a shock hazard that

can cause severe personal injury or death. Use extreme caution to avoid touching electrical

contacts with body, tools, jewelry, hair, clothes, etc. The following procedures are to be

performed only by technically trained and experienced personnel.

4.2.1 Utility-to-Generator Sequence of Events

Refer to the Transfer Switch Interconnect diagram (Appendix B) for transfer switch control wiring and

signal information.

The following steps describe what normally happens when the transfer switch is connected to the Utility,

utility power fails, and the switch transfers to the Generator.

1. While the transfer switch is connected to the utility, utility power fails. K2 de-energizes, which closes

K2-14/11 and opens K2-12/11, removing the ground (B-) signal from TB4-1 and applying the ground

(B-) signal to TB4-2. The generator control starts the generator.

2. After the generator warms up, the generator control signals the relay coil (K1), energizing the relay

coil which opens K1-1/K1-9 and K1-2/K1-10 and closes K1-7/K1-11 and K1-8/K1-12 to move the

transfer switch from the Utility position to the Generator position. The S2 auxiliary switch within the

transfer switch mechanism breaks the signal to the ATS operator coil (C).

3. Limit switch ASW removes the ground (B-) signal (TB4-5), signaling that the transfer switch has

disconnected from the Utility; then the BSW limit switch provides a ground (B-) signal to TB4-6,

signaling that the transfer switch has connected to the Generator.

4. The load is transferred to the generator.