ENGINE AR 1709159 - Caterpillar

the Relay K1 energized as long as STANDBY source power is available. When Relay K2 is de-energized, its normally-closed contacts close. The "NORMAL Voltage Good" signal is delivered to the Microprocessor Based (or In-Phase Monitor or Programmable Logic) board. When the Return To Utility Timer has timed out, the circuit board will then initiate re-transfer back to the NORMAL source and engine-generator shutdown sequences. When the bypass push-button is operated it starts the Time Delay Return To Utility timer of the microprocessor based circuit board. When this timer has timed out, the transfer to NORMAL will occur. For autotest and 7 day exercising (if transfer on exercise has been selected) the bypass push-button must be operated to return to NORMAL.Return To NORMAL Bypass (For Use With In-Phase Monitor Controls)
The Return To NORMAL Bypass option that can be used with the In-Phase Monitor Control does not work in the same manner as the Return To NORMAL Bypass option which is used with the standard Microprocessor Based Control. The In-Phase Monitor Control gives the operator the ability to transfer the load back to the normal power source after normal power is restored thus bypassing the Return To Utility timer. To bypass the Return To Utility timer, the operator should press switch SW4 (normally open). The circuit board will then cause the transfer mechanism to switch the load to the normal power source. SW4 is mounted on the front of the door panel of the Automatic Transfer Switch enclosure.Preferred Source Selector Switch
This option may be used when it is desirable for either source of power to serve as the normal (preferred) source. The other power source then becomes the standby source. The preferred source selector (PSS) switch: is mounted to the door, is manually operated, AND has two positions (SOURCE #1 and SOURCE #2). The PSS switch connects to the transfer switch, to provide a means of selecting the normal (preferred) source.The PSS switch is shown above in the SOURCE #1 position. In this position, UNIT #1 is the preferred source and UNIT #2 is the standby source. The PSS switch shorts wires #253 and #254 together, which provides the signal to start and run UNIT #1. If SOURCE #1 fails with the PSS switch in the SOURCE #1 position, the transfer switch signals the standby power source (UNIT #2) to start.When the PSS switch is in the SOURCE #2 position, UNIT #2 is the preferred source and UNIT #1 is the standby source. In this position, wire #199 is opened and therefore the control system (Microprocessor, In-Phase Monitor or Programmable Logic) thinks SOURCE #1 is not available. The transfer relay (TR) is energized and contacts 2 & 8 are open. The PSS switch shorts wires #178 and #183 together, which provides the signal to start and run UNIT #2. If SOURCE #2 fails with the PSS switch in the SOURCE #2 position; transfer relay (TR) de-energizes and contacts 2 & 8 close, and the transfer switch signals the standby power