ELECTRICAL RESILIENCE Alternator integrity
The alternator is the part of the generator which converts the mechanical energy of the engine into electrical energy, making it vital to the effective performance of the system. Alternator housing, windings, bearings, controls, and cooling systems, should all be included in your maintenance. A resistive-reactive load bank test will help to identify any problems, and test the alternator’s capability to provide the required voltage, and pinpoint any work that needs to be done to prevent the failure of the generator.
The business case for load banks The cost of purchasing a load bank is typically a fraction of the cost of the system which it supports, with rental options negating the need for capital expenditure altogether. When looking at specifying a load bank, the first decision is whether to hire or buy the equipment. Consider how many generators you have on site, and how regularly you’ll need to test them. In hospitals and other healthcare facilities, where power is critical, buying a load bank might be the best solution. However, for those who need to run testing at set intervals, or smaller facilities that have neither the space nor the technical expertise on site, rental can provide an ideal solution.
Key specification considerations for a load bank What type do I need?
The type of load bank you need will vary depending on the applications involved. The most common type – a resistive load bank, can be used to simulate real-life resistive loads, such as incandescent lighting and heating loads, as well as the resistive or unity power factor component of magnetic (motors, transformers) loads. Resistive/reactive load banks combine both resistive and reactive elements in one load bank package, which can also be switched to enable resistive only, inductive, or lagging power factor testing. This type of system can be used to test
the generator set fully at 100% nameplate kVA rating.
Resistive/reactive load banks provide a picture of how well an entire system will withstand changes in load pattern while experiencing the level of power that would typically be encountered under real operational conditions. The inductive loads used in resistive/reactive testing will show how a system will cope with a voltage drop in its regulator. This is particularly important in any application which requires generators to be operated in parallel (as in the case in many hospital settings), where a problem with one generator could prevent other system generators from working as they should.
Where will the load bank test take place? When hiring a load bank, it is important to let your provider know where the equipment will be used, and what the site conditions are like. Load banks work by dissipating energy as heat, making it vital that there is space around the equipment for proper airflow, or that the correct type of equipment, such as a vertical blow machine, is used. When used indoors, temperatures must be monitored to prevent accidental activation of sprinkler systems, overheating, or damage to the load bank. Finally, it helps your supplier if you let them know if the load bank will need to be installed or delivered above ground level, as well as the distance it will be located from the generator. This will ensure that your supplier provides adequate manpower and cabling to successfully carry out testing. It is important to have the details from your generator nameplate or data tag at the ready. To specify the right equipment for the job, your chosen supplier is likely to ask you for the capacity rating of the generator you wish to test. This information can be found on the nameplate (or data tag) on the generator itself. The capacity rating will be specified in KVA and kW at a specified power factor and maximum output voltage. The nameplate will also have information on the voltage, operating
phases, and configuration of your generator, all of which will impact the load bank your supplier will specify. Having a photo of the nameplate on your mobile phone will mean that you have all the information to hand when talking to your supplier.
The potential impact of power failures in the healthcare sector is unfathomable, putting the healthcare system under additional pressure, and causing a threat to life. With this in mind, those specifying, commissioning, or managing, these sites can ill afford to overlook the critical role of load banks when it comes to ensuring a stable, consistent, and constant flow of power.
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Paul Brickman
Paul Brickman is the Sales & Marketing director at Crestchic Loadbanks, and has worked in the power industry for over 20 years. The company said: “Paul’s extensive experience and deep understanding of the power sector in the UK and beyond enables him to fully appreciate the changing landscape of power generation, the increasingly critical nature of back-up power systems, and the risks associated with these systems not performing as expected.”
October 2021 Health Estate Journal 71
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