Conducting periodic planned maintenance checks to test standby generator sets ensures the generator performs as specified in emergencies. Resistive load bank testing and reactive load bank testing are the two methods used to test backup generators.
Trained, experienced technicians must be the ones to conduct standby generator testing. They have the specialized equipment and knowledge of applicable codes to successfully conduct the test according to manufacturer guidelines. The standby generator sets load bank testing procedures covered in this blog post are specified by National Fire Protection Agency code NFPA 110.
Resistive Load Bank Testing
As the most common backup generator testing method, resistive load testing allows the owner to ensure the generator set produces 100% of its output at 1.0 power factor by connecting full kW loading. Resistive load testing verifies that the engine and standby generator system will produce and maintain full load during an emergency without overheating and shutting down.
The test also checks oil, fuel, other critical engine systems, and standby system components. This verifies they will work together as designed and intended. The controlled load bank test can help identify problems or potential system weaknesses. As a result, the issues are addressed before the backup generator is needed. Resistive load testing is also helpful for burning out any carbon deposits in the cylinders or exhaust system. This reduces any wet stacking problems due to frequent operation with light electrical loads.
Key elements of resistive load testing standby generators are to:
- Measures whether the generator is producing at its full power rating.
- Ensure the system evaporates the required amount of engine exhaust gases and heat.
- Verify that it produces the required amount of thermal energy into the engine cooling system.
A typical resistive load test for standby generator sets lasts a maximum of eight hours. However, to meet some government and military requirements, the test may need to run for 18 to 24 hours.
Reactive Load Bank Testing
Reactive load bank testing is commonly used for new backup generator installations. This is primarily because it is a more costly generator set testing method. Since the generator kVA will not deteriorate or change once initially proven, reactive load bank testing is sufficient for the standby generator's first start-up.
This test measures the full kVA nameplate rating at 0.8 power factor of the standby generator set by using a reactive load (equal to 75% of the resistive rating) paralleled with the primary resistive load bank. Reactive load bank testing ensures the proper calibration of load sharing and voltage regulating systems in parallel operation installations.
Critical standby generators with large motor loads often require reactive load testing.
Trust Bay City Electric Works for Load Bank Testing of Your Standby Generator Sets
Routinely checking standby generator sets is essential to ensure the systems are operating as intended. The NFPA 110 (2013 edition) details the testing requirements for Emergency Power Supply Systems (EPSS) and the recommended testing frequency for Level 1 and Level 2 systems in Clause 8.4 (Operational Inspection and Testing).
Bay City Electric Works has a knowledgeable team of technicians who provide generator service for all generator brands. With over 90 years of experience, we're known as the number one electric generator service center in California, Nevada, and Hawaii. We ensure we have a solution for every situation by providing exceptional service, parts, and on-demand rentals to keep your standby generators in tip-top shape.
You can count on Bay City Electric Works' factory-trained and certified technicians to provide quick, efficient service. Contact us to learn more about our company.
