Load Banks Direct Blog

For high power load testing of emergency power systems you can count on Load Banks Direct.

Types of Load Banks

There are three common types of load banks - resistive, inductive, and capacitive.

load bank 1

A resistive load converts electrical energy to heat. Inductive and capacitive loads create reactance in an AC circuit.

A resistive load bank, by far the most common type, provides loading for both generators and prime movers.

The load elements resist current flow linearly and simulate unity power factor loads such as certain types of lighting and heating.

They generate heat which must be dissipated out of the load bank by means of forced air, convection or water cooling.

Resistance is measured in ohms and power is measured in watts. 

load banks 2

An inductive load resists changes in current and as such, when you examine the current, it lags behind the voltage.

Electromagnetic fields are the key to inductive loads, and as such all motors (fans, pumps, etc), solenoids, and relays are inductive in nature.

To accurately simulate these types of loads, inductive load banks are often specified.

Inductance is measured in Henrys.

Inductive loads have two types of power, real power and reactive power.

The real power is based on the work done by the device (such as what a motor is spinning). The reactive power is that which is drawn from the source to produce magnetic fields.

The total power consumed is real and reactive power combined, which is measured in VAR (volts-amps-reactive).

Typically, the inductive load will be rated at 75% that of the corresponding resistive load such that when applied together a resultant 0.8 power factor load is provided. 

load banks 3

Capacitive loads are for many purposes, the opposite of inductive loads.

They resist changes in voltage and the voltage lags the current (or more commonly said "current leads voltage").

Capacitance is measured in Farads. Like inductive loads, capacitive loads also have reactive power, but it's opposite the polarity of an inductive load. Therefore, a capacitive load has a negative VAR.

Capacitive load banks are not as common as resistive or resistive-inductive.

However, they can better simulate certain electronic or non-linear loads typical of telecommunications and computer systems and are used for precise testing of these associated power sources.

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Load Bank Defined

A load bank is a device to which power is delivered.

It is a component which develops an electrical load (i.e. consumes electrical power), applies the load to an electrical power source and converts or dissipates the power output of the source. Load banks are self-contained devices that include the load elements, controls and cooling systems necessary for operation.

In contrast, an actual building load or “real” load uses the power source’s energy output for some productive purpose, whereas the load bank uses the energy output to test, support or protect the power source.
When a load bank is used to test a power generating source by presenting an electrical load, the rated output capabilities of the power source can be verified before being put into actual use. This is critical for emergency power sources.

Load banks are fully controllable and provide a means of applying a predictable load. They often have incremental steps of load so that critical systems can be tested under varying conditions. The load bank is intended to accurately mimic the operational or “real” load which a power source will see in actual application.

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