Load banks simulate “real world” electrical power loads that exist within commercial facilities such as office buildings, hospitals, data centers and shopping malls. Typical real world loads include lighting, electric motors, computer systems and heating and cooling system. Read more about various load bank types below.
RESISTIVE LOAD BANKS
A resistive load bank, the most common type, proves equivalent loading of both generator and prime mover. That is, for each kilowatt (or horsepower) of load applied to the generator by the load bank, an equal amount of load is applied to the prime mover by the generator. A resistive load bank, therefore, removes energy from the complete system: load bank from generator—generator from prime mover—prime mover from fuel. Additional energy is removed as a consequence of resistive load bank operation: waste heat from coolant, exhaust and generator losses and energy consumed by accessory devices. A resistive load bank impacts upon all aspects of a generating system.
The “load” of a resistive load bank is created by the conversion of electrical energy to heat by power resistors. This heat must be dissipated from the load bank, either by air or by water, by forced means or convection.
In a testing system, a resistive load simulates real-life resistive loads, such as lighting and heating loads as well as the resistive or unity power factor component of magnetic (motors, transformers) loads.
REACTIVE LOAD BANKS
A “reactive” load includes inductive (lagging power factor) and/or capacitive (leading power factor) loads. Inductive loads, the more common type, consist of iron-core reactive elements which, when used in conjunction with a resistive load bank, create a lagging power factor load. Typically, the inductive load will be rated at a numeric value 75% that of the corresponding resistive load such that when applied together, a resultant 0.8 power factor load is provided. That is to say, for each 100KW of resistive load, 75KVAR of inductive load is provided. Other ratios are possible to obtain other power factor ratings. Inductive loads are used to simulate real-life mixed commercial loads consisting of lighting, heating, motors, transformers, etc. With a resistive/inductive load bank, full power system testing is possible given the impact of reactive currents on generator/voltage regulator performance as well as effects on conductors and switchgear.
WATER-COOLED LOAD BANKS
Water-cooled load banks allow for indoor installations in controlled environments versus outdoors where units are exposed to the elements. Besides being completely quiet, the water-cooled load bank is highly compact and virtually maintenance free. They are ideal for installation in buildings in central-city areas, industrial parks or office complexes where an outdoor air-cooled unit would be architecturally obtrusive or impossible to install due to space or noise restrictions.