What is Generator Load Bank Testing?

ComRent Load Bank Expert Serviceman

From healthcare facilities to large maritime projects, many of our most important electrical systems rely on megawatt-plus generators for support in the event of a full or partial loss of normal power.

Generators provide standby support for uninterruptible power supplies (UPS), power distribution units (PDU), remote power panels (RPP), bus track, switch gear, rack-mounted servers, and cooling systems, as well as fire alarm systems, lighting, and communications systems.

Using load banks to test generators, both during the commissioning process and periodically throughout their lifespan, is an essential step to ensuring the validity of backup systems and procedures.

Load Bank Testing is commonly undertaken at different levels during the commissioning of a facility depending on the critical nature of the equipment installed and the effect of downtime on the facility owner’s business.  Additionally, testing is done on a recurring basis based on the maintenance guidelines set by company policies, specific industries or regulatory agencies. Finally, testing is often done to validate corrective actions resulting from a facility power system failure or downtime of the facility owner’s business.

Load bank testing is the most flexible method to validate critical power systems and components. Comprehensive testing includes validating the condition and output of generators, Uninterruptible Power Supply (UPS), batteries, transformers, and relays within a facility or utility distribution system.

To perform these load bank tests, contractors use load banks, or large electronic devices capable of simulating real-world electrical loads on power systems in order to test their performance under expected dynamic load conditions.

Load banks can also be used to test different parts of a circuit the location of a faulty connection. With the recent introduction of remote-controlled load banks, as many as fifty load banks can be simultaneously controlled through a single remote device. Remotes help reduce the time it takes to complete load tests by streamlining testing procedure and significantly cutting the number of people required to complete a test.

A wide array of industries rely on generator load bank testing for validation and system maintenance.

  • With the rise of cloud computing, data centers have become one of the most important users of load banks for system testing. Data centers employ resistive load banks to test backup generators, which provide support to a variety of mission-critical components, including UPS, PDUs, RPPs, and rack-mounted computer equipment.
  • The construction and healthcare industries use load banks to test generators and backup power systems. Both merchant marine and military fleets require emergency generator testing with load banks to provide a guarantee that backup systems are fully operational and capable of assuming the full electrical load should a ship experience an outage.
  • Nuclear power plants depend on load banks to test their black start generators in the case of a massive outage where the plant becomes isolated from any other external power networks from where it could draw power. The generators are, therefore, designed to switch on during electricity loss of offsite power to power emergency cooling pumps for the plant.
  • An emerging market for Renewable microgrids may require the use of load banks for commissioning prior to customer connection as well as to optimize the power flow to and from the microgrid system.

Testing Procedures

Load bank testing for a generator or generator set requires a precise set of testing procedures. When conducted properly, comprehensive testing will give contractors greater confidence in backup power systems.

The first stage of testing begins with initiating generator startup. The generators should run until voltage stabilizes. Theautomatic transfer switch then transfers to the backup power source. The operating technician may then step the generator load up to ensure that the backup system can support the load in the required transfer time..

Throughout the load testing process, operators should oversee generator performance and conduct a system check of all components for normal operation. These checks should include asking the following questions:

  • Does the system operate properly under the entire sequence of operation?
  • Does the system accept the load that is expected in operation?
  • Is power quality adequate under emergency power?
  • Is the temperature of the generator staying within normal ranges?
  • Is fuel transferring correctly between the tank and the generator? Could the fuel be contaminated?
  • Do you detect any leaks to fuel, oil, or coolant lines?

Also, be sure to address any alarms or alerts, should they pop up.

For a full load test, the generator should run at rated capacity for several hours. This measure is an important step to ensure peak performance of heating and cooling systems throughout a normal operating sequence.

After the test concludes, the operating technician will remove the load bank first, and all transfer switches returned to their original state. Manufacturer guidelines should be followed for cooling down the generator(s), and operators should make sure to log information covering all aspects of the generator load test, including actual load, conditions, time of testing, etc.

Selecting the Right Load Bank

Each large-scale electrical system has its own ideal load bank testing solution. It is the responsibility of the test operator and the load bank supplier to determine the correct type, capacity, voltage, and other specifications appropriate for each testing scenario.

In the case of backup generators, resistive and reactive load banks are most often used for system validation. The benefits of choosing the right load bank testing solution include:

  • Simulation of the power grid optimized to meet your system needs and requirements.
  • Optimization of the speed, safety, and accuracy of testing according to your project.
  • Precise evaluation of generator system performance.
  • Creation of a customized, true-to-life testing environment that uses a range of scenarios to verify that generator systems are prepared to meet performance expectations.

Data centers involve highly complex circuits and components and, therefore, require high-capacity resistive or resistive/reactive load banks to verify operational capacity, emissions, and safety function of a generator or generator set.

ComRent’s recommended package for load bank testing for a generator in a data center includes an outdoor 2.5-megawatt resistive load bank, a 2.5 megawatt resistive/reactive load bank, and the CR6.25-megawatt resistive/reactive load bank.

Nuclear power plants also benefit from using resistive and resistive/reactive load banks for their emergency generator testing. The 2.5 megawatt resistive and the 1.5 and 4.8-megawatt fine resolution outdoor load banks are among the recommended solution for high-powered plants.

The Importance of Load Bank Testing

Critical systems such as those used in healthcare, cloud computing, military and maritime operation, and power generation require comprehensive backup strategies and rely on generators to guarantee proper function in the event of a partial or systemwide shutdown.

The consistent operation of these systems, both primary and backup, is a matter, in some cases, of life and death. Load bank testing is, therefore, one of the most important measures that contractors can take to ensure these vital circuits are available when you need them.

If you are preparing to load test your project’s generator or generator set, either for commissioning or regular maintenance, and have questions, contact us today.

ComRent specializes in finding the most efficient and cost-effective load bank solution for any project. One of our load bank experts will be able to address your load bank testing needs.

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