Features and Benefits

Cummins Onan offers a complete line of permanently installed residential emergency standby generator systems including 12 kW, 15 kW, 20 kW and larger generator sets with transfer switches. During a power interruption, the Cummins Onan residential emergency standby system will automatically deliver the power to keep homes running smoothly. And it will reset once the power returns. It's that easy.

Basic Description of How the System Operates

Normal Utility Power Mode:

Under normal circumstances when utility power is available, utility power runs through the RST transfer panel contactors, and connects the power to the distribution panel and then to all the electrical loads in a home. The existing electrical system is not compromised in any way by integrating an automatic standby power system in a home. A battery charger installed in the RST Transfer panel enclosure is powered by the utility to keep the starting battery in the generator set charged.

Power Outage Occurs:

When utility power voltage falls to less than 85% of nominal, or fails entirely, the standby power system will automatically go through a start sequence and connect to a home. The RST Transfer panel control constantly monitors the power quality from both the utility source and the generator set. When the transfer panel control senses unacceptable utility power, the control waits for 3 seconds and then sends a signal to start the generator set engine. If the utility power returns before 3 seconds has passed, the generator set engine will not be signaled to start. When the start signal is received, the engine starts and reaches the proper operating speed and AC power is available at the generator set. The transfer panel control senses this, waits for 3 seconds and will then transfer generator set power to the home through the transfer panel contactors. This sequence of operations will usually occur in less than 10 seconds from the time the power outage occurred to the time when generator set power is connected.

Utility Power Returns:

When utility power comes back on and returns to your home, the transfer panel control senses this and will watch for acceptable voltage. After checking for acceptable utility voltage for five minutes, the transfer panel control will signal the transfer panel contactors to re-transfer the load back to the utility source and disconnect the generator set source. At this point, the generator set is "off-line" and will be operated automatically another five minutes to properly cool down. After the cool down cycle, the generator set will be turned automatically off and reset to standby mode.

Automatic Exercise Cycle:

The generator set should be exercised monthly for system readiness. The time of day can be set for the system to operate and it will automatically start and run for a preset period of time. During this exercise period, the power available from the generator set WILL NOT be connected to the home, and utility power will not be interrupted.

Manual Exercise Operation:

The generator set can be operated at anytime from the generator set control panel behind the service access door. Simply move the "RUN/OFF/AUTO" switch to "RUN", and the generator set will start and run. Power available from the generator set WILL NOT be connected to the home, and utility power will not be interrupted. The switch must be returned to the "AUTO" position for fully automatic operation.

System Testing:

The entire system can be tested manually by simulating a power failure. This can be done by manually opening the main circuit breaker ahead of the transfer panel. The standby power system will then go through the start sequence and pickup the home electrical loads. Manually re-closing the main utility breaker will then signal the standby power system to go through the retransfer sequence and return to standby mode.

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Onan Home Standby Generator Sets
ONAN RS12000 ONAN RS-12000 ONAN RS 12000
ONAN RS15000 ONAN RS-15000 ONAN RS 15000
ONAN RS20000 ONAN RS-20000 ONAN RS 20000
ONAN RS45000 ONAN RS-45000 ONAN RS 45000