Load Bank Utilization in Data Centers

When are Load Banks used in Data Centers? 

There are typically four main applications where load banks will be utilized in data centers. 

• Commissioning 

• Expansion 

• Maintenance/ Periodic Testing 

• Component Replacements Each application has varied requirements of power, size, type, and technical specification.

Ensuring the correct load bank is used is vital in ensuring optimum testing.


Commissioning is the process of assuring all systems and components of an industrial facility are tested, installed, and operated to the requirements of the end user. 

Commissioning will help identify potential issues and ensure components and systems are working safely and efficiently. Load testing in the commissioning phase will ensure any faulty electrical components or systems fail and are replaced accordingly before going ‘live’. Real life load is not always available in the initial phases of construction as many data centers plan to expand as they go. Load banks are the only practical way of simulating real life load and will provide reassurance of the quality of components. 

During the commissioning phase of a data center numerous critical components should be tested by load banks including back-up diesel generators, UPS systems, HVAC systems, bus tracks and tap offs, power distribution units, remote power panels, and server racks. 

A variety of types of load banks can and should be utilized to ensure testing is performed correctly. Maintenance/Periodic Testing The importance of back-up power supplies in data centers is critical. Numerous power and back-up power sources need to be rigorously maintained. Most data centers have a back-up UPS systems and diesel generators to supply power if the grid fails. Regular maintenance is vital in ensuring reduced down time in data centers, in the US an average cost of one minute of downtime is estimated at $7900 USD1 . 

Load banks are the most effective way to test and stress electrical systems for maintenance and periodic testing purposes. A variety of load test types can be configured for specific maintenance purposes and reports will identify issues in systems that can be replaced or fixed to ensure efficient operation.


Routinely, data centers are built larger than initially required with the aim to expand. As expansion occurs, correct simulation of power usage and cooling adaptation will be required. New components and hardware must prove operation and efficiency, especially in locations where sensitive or important information may be stored. Load banks are the leading technology for simulating the real life power conditions of server racks. Most load banks will have the sophistication to provide detailed test reports. These reports can be used as proof of electrical compliance for clients who wish to purchase server space. 

Component Replacements Load testing is an effective process for testing and verifying all components in a circuit. Referring to the bathtub curve , failure starts to rise as components age and reach the end of their life cycle. 

The graph shows in early life there is an initial high failure rate, however this decreases as defective products are removed and installation errors are reduced. As the product gets older and wears out the failure rate begins to increase again, creating this bathtub curve. This directly correlates to data center electrical systems and components. Load banks can effectively test electrical systems, which reduces potential future downtime

Back-up Diesel Generators 

The majority of data centers have a diesel generator located on site to supply power in the event of an outage. Loss of power in data centers can cost people and businesses millions of dollars via lost sales, loss in customer confidence, and steep financial penalties for missing service level agreement contracts. Correct operation and maintenance of the diesel generator is vital in ensuring maximum uptime of a data center. Load bank testing is the preferred method of ensuring efficient operation of a gen-set. 

A load bank will simulate electrical load and allow the operator to find potential issues and faults on the gen-set so in the event of a power outage it will work as required. A load test will ensure correct operation of the voltage regulator, governor, cooling system, fuel system, control system and also prevents the dangers of wet stacking that are typical on lightly loaded generators.

Either a purely resistive or a resistive inductive load bank can be used to test the diesel gen-sets. A purely resistive load bank will confirm an engine’s ability to provide kW and deliver an equivalent amount of kVA. A resistive inductive load bank will fully test the power supply as it will provide impedance supply currents out of phase with voltage. Diesel generators should be load tested frequently. 

Typically, in larger data centers permanently installed containerized resistive inductive load banks are used to meet the higher capacity and endure tough outdoor conditions. Many load bank suppliers have control systems to perform automatic and transient load tests. The load test results can be saved and filed to build a picture of the health of a generator over time. Alternatively, load bank control can be integrated into existing control systems typical in larger data centers.

This article has been extracted from White Paper Load Bank Utilization in Data Centers by ASCO

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