Product Manual B

4. Operation7-2018
55A045R242 (Issue 12) Copyright © 2018 Cummins Inc.
Power Outage Sequence
The sequence of operation after a power outage (when the generator set is in
Auto Mode) is as follows:
1. In normal operation, the utility power is running to the transfer switch and
then to the building load, and the generator set is off.
2. The utility power turns off (power outage).
3. One second after the power outage, the transfer switch sends the
command to the generator set to start.
4. The generator set starts and provides voltage to the transfer switch, but
the transfer switch does not switch (allowing the voltage to go to the
building) until after a delay.
FIGURE 16. TIME REMAINING UNTIL TRANSFER SCREEN
5. Five seconds after starting, the generator set provides a signal to the
transfer switch to transfer the building load to the generator set.
FIGURE 17. BUILDING LOAD TRANSFER IN PROCESS
6. The transfer switch switches the generator set power to the building load.
The building is now running on generator power.
FIGURE 18. GENERATOR SET POWERING BUILDING LOAD
7. When the utility power is back and providing voltage to the transfer
switch, the transfer switch waits for utility power stability.