Load Banking 101: Importance Of Testing A Generator

Have you ever seen a generator technician testing a genset? They often connect the unit with heavy-duty cables to a large, toaster-like device. What is that large electrical control box with all the switches and caution signs? That’s a load bank unit—and techs use this equipment to test the functionality of an industrial generator.  

Load bank units are made to keep and check electrical power sources. This includes industrial standby generators for our applications.

The unit applies a load to a power source. It then releases the energy through resistant elements, which turns into heat (thus the caution signs). Internal fans in the load bank cool these elements to prevent them from overheating.

Load banks can be part of a genset. You can permanently attach them to the enclosure as an added upgrade. They can also be portable, like many units in the field services arsenal at Generator Source. This lets our teams visit client sites to test generators as part of yearly maintenance plans.

The technicians at Generator Source use load bank test units. This process ensures that the generators for sale are ready for a new job. Generator Source puts all generators through a 31-point inspection process which includes a load bank test. No different from an automobile dealer where they certify a used car for sale.    

During a load bank, the technician slowly adds load to a generator. About every 20-30 minutes, the technician adds 20% power. At each interval, they will check all measurables. Then add another 20% more amperage and repeat the process until they have added up to 80% load and filled out a chart. The test usually takes 1 to 4 hours. It certifies a generator and ensures it is ready to provide standby power on site.

How It Works
A load bank connects to the output of a power source, such as a generator. It shows electrical characteristics to mimic a normal operating load. The load bank then dissipates the power output that the power source would normally consume. 

Purpose
Load banks are used to test the quality and reliability of power sources, such as industrial and commercial generators. Load bank units can help identify problems with faulty designs, improper settings, and defective or damaged equipment.  Think of a load bank test much like a dynamometer for a car. It helps the car run in a stationary position as a mechanic monitors the diagnostics. This test measures horsepower, performance, and more.  

Types
Several types of load banks exist: 
·      Resistive: The most common type, used for general-purpose generator sets. You can use a resistive load bank to fully test the generator set at 100% of the nameplate kW rating. The generator cooling, fuel, and exhaust systems will also fully load. 
·      Reactive: Less common than resistive models, but effective for testing emergency generators in business-critical operations. 
·      Resistive-reactive: Combines reactive and resistive testing methods. 
·      Inductive: Uses electromagnetic fields to test power equipment, typically rotating devices like motors. An inductive load bank works with resistive units. It is used to test a lagging power factor load. This provides the capability to test the generator set fully at 100% of the nameplate kVA rating.

Time To Get Your Generator Checked?
 When was the last time you had your generator load bank tested? Our field services teams can schedule a test and make sure your genset is ready for the next power outage. Learn more, click here.
  
Story Summary

What is a load bank?
A load bank is a special tool. It tests and maintains electrical power sources, such as industrial standby generators.

It applies an electrical load to the power source. The system releases the energy as heat through resistive parts. Internal fans help cool these units.

How does a load bank work?
An operator connects a load bank to the generator's output. The load bank simulates a normal load by showing electrical characteristics. It then dissipates the power output that the power source would normally consume.

During a test, technicians slowly raise the load by 20% every 20 to 30 minutes. They check the measurements at each step until they reach 80% load.

What is the purpose of load bank testing?
Load bank testing serves several important purposes:

• Verifies generator performance and reliability
• Identifies potential problems or faulty equipment
• Ensures the generator can handle its rated load
• Prevents issues like wet-stacking in diesel generators
• Provides assurance that the generator will work properly when needed

• Resistive: Most common, used for general-purpose generator sets
• Reactive: Effective for testing emergency generators in critical operations
• Resistive-reactive: Combines reactive and resistive testing methods
• Inductive: Uses electromagnetic fields to test rotating devices like motors