Our Energy Working For You: Benefits and Considerations of Standby Generators
By Al Reiter, Energy Advisor
MVEC occasionally fields questions from members considering standby generators. While MVEC’s service availability hovers around 99.98%, the effects of the derecho that struck Iowa are still fresh in our minds. The cooperative continues to improve our distribution system for weather events, but for some members, having standby generation adds a level of safety and reliability for their situation. In this edition of Our Energy Working for You, we will review some of the options for standby generation, information for your electric service that will help in sizing a system, and most importantly, how to safely use your standby generator.
A basic option for small load usage is a portable, manually started generator. These are not intended to connect to your electrical system, but rather, to power a few plug-in appliances like a freezer or small heater. They are going to be usually less than 5,000 watts and some of the more high-end units supply both 120 and 240 Volt.
A more common option for standby generation is a whole house/farm generator that is in the 10-50 kilowatt (kW) range. This will be interconnected into your wiring system and has options to be started manually or automatically when you are not home. These will typically supply the normal load that you will need at your home during an outage. For critical loads, like life-safety equipment found in a hospital, or industrial process where damage or loss would occur with an outage, emergency generators are used. This type of generator will require to pick up all loads within 10 seconds.
For members considering purchasing a standby system, knowing what size of generator you will need is a good first step. As you look at options, you will see that generators will have a continuous rating and a peak rating. MVEC can assist you with sizing the generator by providing a history of your load profile that shows the demand in kilowatts that your service has used. Because generators have to be sized for both the running load and the increased power used to start the load, sometimes called surge power, history of both is useful to your generator supplier.
If you decide to proceed with the purchase of a generator that connects to your home or business’ electrical system, you will need a safety switch installed by a reputable electrician. This safety switch, sometimes called a double throw switch, ensures that electrical devices in your home can’t be connected to standby power and normal utility power at the same time which would cause damage. There is another important reason: the safety of MVEC linemen working in all conditions to get power restored. While the electrical transformer does an efficient job of stepping the primary line voltage down from 7200 Volts to the 120/240 Volts you use, it does an equally efficient job of stepping up the voltage. If a standby generator is not properly installed and sends voltage back onto the cooperative power system, it presents a shock hazard to linemen working on the power line. As a courtesy, it would also be a good idea to contact MVEC (800-927-6068) to let us know that you are installing a generator on your property.
Once you have a generator installed, the work doesn’t end there. To ensure it is ready to perform when you need it, a generator should be exercised periodicallyto make sure everything is working. If it is a manually connected generator, it is a good practice to go through the steps to set it up and operate it.
Like insurance, a standby generator provides a level of safety and reliability if an outage occurs.