Cummins Onan

How the System Works

• 1.
  Transfer switch monitors voltage coming from utility
• 2.
  Transfer switch senses when utility power fails or drops below an acceptable level (brown out), and sends a signal to start the generator
• 3.
  Transfer switch automatically disconnects the utility power from the electrical circuits in your home, and reconnects them to the generator
• 4.
  Generator continues to supply electrical power to your home until utility power is restored
• 5.
  Transfer switch senses when the utility power is restored, automatically disconnects the generator from your home circuits, and reconnects the utility power
• 6.
  The Cummins Onan Generating system automatically re-sets itself for the next power outage

What Happens When
The Power Goes Out

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 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 contractors. 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 contractors 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

Routine Operation and Maintenance

A common concern for homeowners is how to maintain their Cummins Onan standby generator once it is installed. Not to worry. Maintaining a generator is similar to maintaining an automobile and maintenance is essential for top performance and long life. Just like a car, you will have an owner’s manual for your generator unit with very specific directions and maintenance intervals in grid form. It will tell you how to maintain your generator and allow you to record things like running hours and maintenance performed. You will find that changing the oil, checking the battery/connections, changing an air or oil filter, and visually inspecting your unit’s components are typical maintenance requirements. Warranty work, however, must be performed by an authorized Cummins Onan Dealer or certified technician. For more extensive repairs or peace of mind, feel free to contact your Cummins Onan dealer or distributor for more information.