Guardian Technologies 4390 Utility 2 Terminals, Test 29- Check Voltage AT Utility Closing Coil C1

SECTION 3.4

DIAGNOSTIC TESTS

PART 3

V-TYPE PREPACKAGED TRANSFER SWITCHES

PROCEDURE:

1.Make sure that all main line circuit breakers in the utility line to the transfer switch are “On” or “Closed.”

2.Test for utility source line-to-line voltage across terminal lugs N1 and N2 (see Figure 1). Normal utility source voltage should be indicated.

RESULTS:

1.If low or no voltage is indicated, find the cause of the problem and correct.

2.If normal utility source voltage is indicated, go on to Test 28.

3.For Problem 14 ONLY, if voltage is good, repair or replace Wire N1A/N2A between Transfer Switch Lugs N1/N2 and Fuse Holder connections.

TEST 28 - CHECK VOLTAGE AT UTILITY 1 AND

UTILITY 2 TERMINALS

The UTILITY 1 and UTILITY 2 terminals in the transfer switch deliver utility voltage sensing to a circuit board. If voltage at the terminals is zero or low, standby generator startup and transfer to the Standby source will occur automatically as controlled by the circuit board. A zero or low voltage at these terminals will also prevent retransfer back to the Utility source.

PROCEDURE:

With utility source voltage available to terminal lugs N1 and N2, use an AC voltmeter or a VOM to test for utility source line-to-line voltage across terminal block Utility 1 and Utility 2 terminals. Normal line-to-line utility source voltage should be indicated.

Figure 4. Transfer Switch Terminal Block

RESULTS:

1.If voltage reading across the "Utility I" and "Utility 2" terminals is zero, go to Test 30.

2.If voltage reading is good, go to Test 29.

3.For Problem 14 ONLY; if voltage is good, repair N1/N2 open wiring between Transfer Switch and Generator.

TEST 29- CHECK VOLTAGE AT UTILITY

CLOSING COIL C1

DISCUSSION:

Utility source voltage is required to energize utility closing coil C1 and effect retransfer back to the "Utility" source. This voltage is delivered to the utility closing coil via Wires N1A and N2A, the transfer relay’s normally-closed contacts (relay de-energized), Wire 126, Limit Switch XA1, and a bridge rectifier.

PROCEDURE:

1.On the generator control panel, set the AUTO-OFF- MANUAL switch to OFF.

2.Turn OFF the utility power supply to the transfer switch, using whatever means provided (such as a utility source main line circuit breaker).

3.Set the generator main line circuit breaker to its OFF or "Open" position.

4.Check the position of the transfer mechanism main contacts. The moveable load contacts must be connected to the stationary utility contacts. If necessary, manually actuate the main contacts to their "Utility source side (load connected to the "Utility' source).

DANGER: BE CAREFUL! HIGH AND DANGEROUS VOLTAGES ARE PRESENT AT TERMINAL LUGS WHEN THE GENERATOR IS RUNNING. AVOID CONTACT WITH HIGH VOLTAGE TERMINALS OR DANGEROUS AND POSSIBLY LETHAL ELECTRICAL SHOCK MAY RESULT. DO NOT PERFORM THIS VOLTAGE TEST WHILE STANDING ON WET OR DAMP GROUND, WHILE BAREFOOT, OR WHILE HANDS OR FEET ARE WET.

5.Disconnect Wire N2A from the utility closing coil (C1). Connect one meter test Lead to Wire N2A. Use a suitable and safe connection to this wire, such as an alligator clip that attaches to the meter test probe. Isolate this wire and test probe from any other potential source or ground.

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