What is the difference between weekly exercising and a load bank test?
Exercising your standby generators weekly is basically an unloaded test. For natural gas or liquid propane units, exercising confirms that your generator can run, but does not check your unit’s performance which can be critical for ensuring you’re ready for a real power outage event. For diesel engine-driven generator sets, unloaded tests or weekly exercising can cause ‘wet-stacking’. Wet stacking is when unburned fuel accumulates in the engine exhaust. This is caused by under-loading a generator. When exercising a generator, or running it for short duration outages while underloaded, the engine may not reach its optimum operating temperature. When this is allowed to continue for long periods of time, the unburned fuel accumulates and can become harmful to the engine’s efficiency and life span.
How is a load bank test performed?A load bank is a piece of specialized equipment that produces artificial loads on a generator. It does this by bringing the engine to a certain operating temperature and pressure to simulate the process of the equipment being used during an emergency situation. An easy way to think of it is that the purpose of load bank testing essentially acts as a dry run for emergency generator use and allows any flaws or problems to be exposed before a critical situation.
Step One:All fluid levels are checked to ensure the fuel tank is full and the oil level is correct. If the generator is water-cooled, it is also important to check the radiator or coolant tank.
The generator is started and allowed to reach normal operating temperature. Our Technician watches and listens for any possible issues such as abnormal noises. If any problems are detected, the testing process is stopped until the mechanical failure is diagnosed and corrected.
Our Technician then begins connecting the loads by starting with any large 200-volt loads and adding smaller 110-volt loads. This continues until each leg carries 50% on any one leg.
While distributing voltage, our Technician checks the amperage of each leg with an ammeter. In cases where a 110/220-volt single-phase generator is being tested, the voltage of each leg is recommended to fall between 105 and 125 volts.
Our Technician continues monitoring the generator while maintaining the same load for the duration of the test, continuing to listen for noises or any signs of malfunction. If an issue is discovered, the test is shut down to minimize damage until repairs are made.