RLC Load Banks: Growing Demand

What are Load Banks?

Load banks are used to commission, maintain, and verify electrical power sources such as diesel generators and uninterruptible power supplies (UPS). The load bank applies an electrical load to the power source and dissipates the resulting electrical energy through resistive elements as heat. The resistive elements are cooled with motorized fans within the load bank construction.

Load banks can either be permanently installed at a facility and connected to a power source, or portable versions can be used for testing when required. Load banks are the best way to replicate, prove and verify the real-life demands on critical power systems.

What are RLC Load Banks?

Whereas a standard load bank only provides resistive load, an RLC load bank provides resistive (R), inductive (L), and capacitive (C) load.

The resistive component simulates the active or real power load of the system being tested. Resistance is generated when current passes through conductors in a load bank element, producing heat and placing a corresponding electrical load on the power source. Resistive load elements can produce precise amounts of load at a power factor equaling 1.

The inductive component also known as the reactive element use wire coils to create inductive fields. The power used to create and maintain these fields loads the power source under test. Compared to resistive loads, inductive load current peaks after voltage. Consequently, inductive coils produce lagging power factors. Because they produce lagging power factors, inductive load is used whenever the power factor of a test load must be reduced.

The capacitive component use capacitors that store electrical charge. They resist changes in voltage, which causes current to peak before voltage during each electrical cycle. As a result, capacitive load elements provide a leading power factor, and can be used to raise power factors of circuits.

Avtron open wound load bank elements
Resistive Elements
3 inductors in a load bank
Close up of a capacitor
Avtron 6110 Load Bank
An RLC Load bank in an enclosure

RLC load banks find application in highly specialized scenarios. With the rapid expansion of the Internet of Things (IoT) and the consequent surge in data center construction, there is a rising demand for RLC load banks to facilitate intricate and essential power verification processes.

RLC load banks can be assembled either within a single enclosure or as individual resistive, inductive, and capacitive units. When an RLC test is necessary, these separate units can be interconnected and networked together to function as a unified RLC load bank. This approach is particularly advantageous in the rental market, where rental companies aim to avoid tying up their entire inventory with RLC load banks. By having separate units available, rental companies can cater to the higher demand for resistive-only testing and customize load banks from their existing fleet inventory to achieve optimal flexibility. Avtron’s SIGMA system serves as a comprehensive control platform capable of managing various types of load banks.

RLC Load Bank Applications

Commissioning Diesel Generators
Commissioning ensures reliability and provides proof of performance in a safe environment before a facility or expansion goes ‘live’. RLC load banks allow for comprehensive testing of generator performance during the commissioning phase and are perfectly suited to more stringent gen-set test applications such as in data centers.

The unit can be specifically controlled to simulate various power factors, reactive loads, and load fluctuations. This testing helps evaluate factors such as voltage regulation, frequency stability, transient response, and overall performance of the generator during load changes.

RLC load banks are used to verify the voltage and frequency stability of the generator. The load bank applies a load that fluctuates within specified limits, testing the generator’s ability to maintain steady voltage and frequency output under varying load conditions. This is crucial for ensuring a stable power supply to the facility’s critical equipment before installation.

In facilities where multiple generators are configured for parallel operation, RLC load banks are used to test the synchronization and load sharing capabilities of the generator set. Load banks are connected to each generator in the parallel configuration to simulate the combined load, ensuring that the generators work in harmony, share the load evenly, and respond accurately to load changes.

RLC load banks are also employed in system integration testing. They are used to verify the interaction and performance of the generator with other components of the power distribution system, such as transfer switches, automatic voltage regulators (AVRs), and other control systems. This ensures that the entire power infrastructure operates seamlessly and reliably.

Commissioning USP systems
UPS (uninterruptable power supply) systems are used in large facilities with critical power supplies like healthcare, financial institutions, and data centers where it is imperative that the power never fails. The UPS systems will keep power on until the generator power can take over. Because of their very critical nature, UPS systems must be tested so that all potential scenarios are covered in the commissioning.

The UPS systems need to handle both lagging (inductive) and leading (capacitive) power factors effectively. RLC load banks allow for the verification of UPS system performance under different power factor conditions. By adjusting the inductive and capacitive components of the load bank, the commissioning process can ensure that the UPS system can handle and compensate for these power factor variations.

Furthermore, RLC load banks also help test the synchronization and switching capabilities of UPS systems. During commissioning, the load bank can simulate power interruptions by reducing the load applied to the UPS system. This tests the UPS system’s ability to smoothly transition from utility power to battery power without any disruption or voltage fluctuations that may cause certain electrical equipment to fail.

Research and Development
Historically, RLC load banks have been used by research and development departments at power system manufacturers for end-of-line testing. Currently, as UPS systems and gen-sets are manufactured, they are subjected to stringent standards and are tested throughout development by RLC load banks to ensure that they are able to correctly react to whatever deviations the load bank might present to it.

With a gradually increasing emphasis on renewables and microgrid applications, there are opportunities for RLC load banks. Smaller, renewable sites that act as stand-alone, island-mode, generating facilities that are not tied to utilities, must be able to hold frequencies very tightly. To verify this, an RLC solution is needed that can test performance at different power factors through lagging or leading before coming online and connecting to a housing development or office block.

While there are not many of these renewable sites now, there is an expectation that over the next few years there will be an increase and it will be a developing market for RLC load banks for load testing applications.

Why Avtron RLC Load Banks?

With the continued investment in new data centers and the increasingly data-driven world, there is an increasing need for more backup power systems and thus, for more RLC load banks.

Avtron has a long history of providing innovative, high-quality load bank solutions. Avtron’s load banks are designed to be used with SIGMA, a multifunctional embedded load control system specifically designed for Avtron load banks. SIGMA is the leader in simplicity, ease of use and accuracy. SIGMA brings market-leading solutions to today’s power testing requirements which can require high-level instrumentation, data capture and verification.

Interested in an RLC Load Bank?

Our load bank specialists are ready to talk to you about your next RLC application.

Contact Sales

Related Articles

Two people shaking hands

Contact Sales

Speak to our expert sales engineers about your load bank requirements.

Engineer on site at an electrical sub station

Contact Support

Have a problem with your load bank or application?

Go to Knowledge Base

Extensive information about our load banks is just a click away.


Subscribe to our mailing list to receive our latest educational insights and industry perspectives. 

I’d like to receive news and commercial info from Avtron Power Solutions via electronic communication means such as email, and I agree to the collection of information on the opening and clicks on these emails (using invisible pixels in the images), to measure performance of our communications and improve them. For more details, please read our Privacy Policy.
Skip to content