Cummins Liquid Cooled Standby Home Power Generators

Were you in the dark during the last power failure? You can eliminate worries that a power outage will leave your home susceptible to flooding, allow your refrigerated or frozen food to spoil, or that you’ll have to suffer through a withering heat wave or freezing cold without heating or cooling. Standby generators keep your home powered when the electric utility supply fails.

Cummins Onan 20kW LP Liquid Cooled Standby Generator

Cummins Onan 20kW LP Liquid Cooled Standby Generator
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Cummins power generation systems include 20 kilowatt liquid-cooled standby generator systems, with models that operate on natural gas or on LP gas. These standby power packages include 100 or 200-amp automatic transfer switches designed for use with the liquid cooled generators. The permanently installed generator sets operate automatically during an outage to keep your home supplied with electrical power. Liquid-cooled backup generators run cooler, so they use less oil and are less prone to high-temperature shutdowns which makes them very reliable. Applications include small business, light commercial, or residential installations where reliable backup power is required.

Liquid-Cooled Cummins Power

The RS20L series of generators from Cummins produce up to 20 kilowatts of electricity and are powered by General Motors 3.0-liter, four-cylinder engines. The engines in these liquid-cooled generators are similar to those found in automobiles. A fan blows air through a radiator filled with an antifreeze mixture that is pumped through the engine to cool it. Norwall offers four liquid-cooled packages that combine an LP or NG-powered generator with a 100 or 200-amp automatic transfer switch. Power interruptions are detected by the transfer switch, which signals the generator to start after a short delay to guard against momentary outages. The generator runs for a few seconds to warm up, and then transfer switch begins supplying the house with generator power.

Automatic Transfer Switch

Cummins Onan RS Series 20,000 Watt Liquid Cooled Standby Generator offers many features, a fully weather protective enclosure, significantly quieter operation, comes on automatically when you need it and shuts down automatically once main power is restored.

Cummins Onan RS Series 20,000 Watt Liquid Cooled Standby Generator offers many features, a fully weather protective enclosure, significantly quieter operation, comes on automatically when you need it and shuts down automatically once main power is restored.

The RSS 100 or 200 amp transfer switch from Cummins Power Generation selects between the normal utility supply and emergency backup power. The ATS programmable functions are controlled by the Powercommand Microprocessor Control panel located inside the transfer switch. Programmable functions include the generator start delay: 0 to 10 seconds, transfer to emergency power: 0 to 300 seconds, transfer back to utility power: 0 to 30 minutes, and the no-load cool-down period: 0 to 30 minutes. The exercise cycle clock is configurable in 7 day increments of 7, 14, 21, or 28 days. A 2-amp regulated battery charger is included within the transfer switch. The transfer switches have a NEMA 3R rating which allows for outdoor installation. Two installation configurations are commonly used. The first installation places the transfer switch between a main circuit breaker or disconnect switch and the main service panel. In this configuration, the entire main panel is served by the automatic transfer switch which chooses the utility supply during normal operation and standby generator power whenever utility power is lost or sags below acceptable levels. The transfer switch current rating―either 100 or 200 amperes―must equal or exceed the main circuit breaker rating. Most newer homes have a main circuit breaker rated at 200 amps. The second installation configures the transfer switch to supply only selected circuits in a sub panel. The ATS receives utility power via a circuit breaker in the main panel and feeds the sub panel. When utility power is dropped, the transfer switch selects backup generator power. In this configuration, only the circuits in the sub panel receive power during an outage. Circuits located in the main panel are not powered.


Liquid cooled generators from Cummins Power Generation feature very quiet operation. They have an all-aluminum, attractive enclosure that resists rust and corrosion. The engine runs smoothly with lower vibration and an electronic governor that keeps the speed at 1800 RPM for a constant 60 hertz AC signal. An engine coolant heater for cold-weather operation is included. A 2 year/2000 hour consumer warranty is standard with additional 2 and 5 year warranties available as options.

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Country Living
Comment by Jim C. on 9th Nov 2014

My Mom and Dad are both in their 80's and live in the country. With the installation of the 6551 I can rest assured that they will never be without power, heat, ac and water. this is a great unit and worked perfectly upon startup. Should have installed this a lot sooner for them.

By the way, my son-in-law also has one for his home. I live in a motorhome or I would have one also.

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