Guardian Technologies 4390 Initial Transfer To The Standby Source, Section, Operational Analysis

SECTION 4.2

OPERATIONAL ANALYSIS

PART 4

DC CONTROL

INITIAL TRANSFER TO THE

"STANDBY" SOURCE

The generator is running, the circuit board’s "engine warm-up timer" is timing, and generator AC output is available to transfer switch terminal lugs E1 and E2 and to the open contacts on the transfer relay. Initial transfer to the "Standby" power supply may be briefly described as follows:

The circuit board delivers a 12 volts DC output to the transfer relay (TR) actuating coil, via Wire 194, and terminal A of the transfer relay (TR) in the transfer switch. This 12 volts DC circuit is completed back to the board, via transfer relay terminal B, and Wire 23. However, circuit board action holds the Wire 23 circuit open to ground and the transfer relay (TR) is de-energized.

When the circuit board’s "engine warm-up timer" times out, circuit board action completes the Wire 23 circuit to ground. The transfer relay then energizes and its normally open contacts close.

"Standby" power is now delivered to the standby closing coil (C2), via Wires E1 /E2, the normally open transfer relay contacts, Wire 205, limit switch XB1, Wire B, and a bridge rectifier. The standby closing coil energizes and the main current carrying contacts of the transfer switch are actuated to their ’Standby" source side.

As the main contacts move to their "Standby" Figure 5. Circuit Condition - Initial Transfer to Standby source side, a mechanical interlock actuates

limit switch XB1 to its open position and limit switch XA1 to its "Utility" side position. When XB1 opens, standby closing coil C2 3 de- energizes.

"Standby" power is delivered to the "Load" terminals (T1/T2) of the transfer switch.

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