Product Manual

Table Of Contents

2. Introduction7-2019

No. Description No. Description

1 Utility (Normal Power) 4 Over Current Protective Device

2 Over Current Protective Device (Customer

Supplied)

5 Generator Set (Emergency Power)

3 Load

FIGURE 2. LOAD TRANSFER SWITCH (TYPICAL FUNCTION)

2.3 Transfer Switch Function

Automatic transfer switches, capable of automatic operation without operator intervention, perform the

basic function of transferring the load to the available power source.

This automatic transfer switch, capable of automatic operation without operator intervention, is designed

for utility-to-generator applications. In utility-to-generator applications, the transfer switch performs the

following functions:

1. Senses the interruption of utility power

2. Sends a utility unavailable signal to the generator set

3. Receives transfer command from generator set control

4. Transfers the load to the generator set

5. Senses the return of utility power

6. Sends utility available signal to generator set

7. Receives retransfer command from generator set control

8. Retransfers the load to the utility

The transfer switch design is intended to signal when the utility voltage is not present and when it returns.

The utility sense relay coil will energize or stay energized at voltages other than nominal. Therefore, the

unit should not be expected to signal a failed utility to the generator set during undervoltage or overvoltage

conditions.