A load bank is a device which creates resistance to consume electrical energy when activated. Simply put, try and think of it as a giant hair dryer, with large resistive heating elements which convert electricity to heat, and a fan to cool things off. Load banks can vary in size, and are usually rated in watts (W) or kilowatts (kW) based on how much power they can consume. Activating the device doesn’t have to happen all at once – most load banks are configured with several ‘steps’ which allow you to control how many watts are being consumed. Load banks can be used in two common practices; generator load testing, and automatic load sensing.
Load testing is done on all new generators, and periodically throughout the life of the machine, to simulate the effects of real world usage. It’s similar to test driving a car before it is sold; you want to make sure everything works as well as it looks. These tests are usually done for a minimum of one hour, but can be much longer in critical applications.
Automatic load sensing is more involved, and has to do with the generator application on-site. In a rudimentary example we can imagine a site with two electric motors that are each rated at 50hp (horsepower). Motor 1 (50hp) runs a conveyor belt which is on all the time. Motor 2 (50hp) runs a fan which is only on for six minutes every hour. In order to run both motors at the same time, the generator must be large enough to deliver the equivalent of 100hp in electricity, or about 75kW (kilowatts). However, for 90% of the time, the only load on the generator will be 50h, or about 37kW (Motor1). This creates a scenario where the engine is being ‘underpowered’ for most of its use, which can cause additional wear and tear on the engine and turbocharger, carbon buildup, and increased oil consumption.
This is where the load bank comes in – it can be programmed to automatically soak up some of that unused power. In our scenario, when Motor1 is consuming 37kW and Motor2 is off, the load bank could be activated to consume 15kW of power. In which case, our 75kW generator is now running at around 52kW (37kW + 15kW), or 69% load. The load bank can be programmed to automatically sense how much power the generator is using, and activate the proper steps to maintain a minimum of 66% load. When Motor2 comes online, the load bank will sense the increase in consumption and instantaneously deactivate itself. You can see how our scenario would be made much worse if Motor1 is diminished to 10hp, but Motor2 remains at 50hp. These kinds of scenarios are common, especially in the oil and gas industry, and it is important the proper steps are taken.
AltaStream offers complete automatic sensing load bank solutions, designed specifically for your application. Please contact us and we would be happy to discuss your next project!