In any electronic system there is an electronic load, or amount of voltage, that the system carries. Each part of the system must be able to handle the electronic load that it is designed to transmit. To help test a system’s ability to handle this voltage, a load bank is used. It simulates a full load and full capacity of the system without having to interrupt ongoing operations to complete the test, and without having to risk exposing expensive equipment to an untested system.
A load bank, also known as a dummy load, is a testing device that develops and applies an electronic load to a power source. It then measures the source’s power output. Whereas a "real" power load can be unpredictable, a load bank provides a consistent, fully controlled load so that the system can be adjusted and tested at different power levels as needed.
In manufacturing and industry, load banks are used in a variety of applications. They can be used to test turbines and generators. Back-up power systems — such as batteries or UPS systems — and ground power can also be tested using load banks. In some cases they can also be used to help resolve problems such as carbon build-up on piston rings or wet stacking in diesel engines.
Load banks are useful tools for testing generators. The main reason is that it is rare that enough load is available to fully test a generator without stopping the regular operations of the plant. A load bank allows the plant operator to get an accurate test of the generator’s capacity and functionality. This is important because operating an underloaded engine will cause a great deal of excess wear.
There are three common types of load banks: resistive, inductive and capacitive. Of these, resistive is the most common. A resistive bank is used to test generators and prime movers. For every unit of load that is applied to the generator, the same unit of load is applied to the prime mover. In other words, the resistive load bank removes energy from all aspects of the generator system, providing a more complete test.
An inductive load bank tests lagging power factor loads. The amount of the inductive load is usually 75% of the corresponding resistive load. This type of device allows the user to test a mixture of different types of loads in a commercial environment, such as lighting, motors, and heaters. In a capacitive load bank, a leading power factor load is created. These devices are helpful for testing loads on systems used in telecommunications or computer industries.