Product Manual

Table Of Contents

4 Troubleshooting

4.1 Introduction

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

transfer switch.

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 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 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 Set Sequence of Events

Refer to the transfer switch interconnect diagram at the back of this manual 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 set.

1. When utility power fails, K2 is de-energized which closes contacts K2-11/K2-12 which applies B-

signal to TB4-1. This signals the generator set to start.

2. When the generator set reaches nominal voltage and frequency, it sends a signal to energize relay

K1 (B+ for C13N6, C17N6H, C20N6H: B- for all other models), which opens contacts K1-1/K1-9 and

K1-2/K1-10, and closes K1-7/K1-11 and K1-8/K1-12. This disconnects the load from the utility and

connects to the generator set supply.

3. The S2 auxiliary switch within the transfer switch mechanism opens, removing power from the

operator coil C.

4.2.2 Generator-to-Utility Sequence of Events

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

generator set, utility power returns, and the switch moves from the Generator set position to the Utility

position.

1. The utility returns.