Data Centres: The Prominence of High Voltage Testing

By Chris Dodds on 27th March, 2015

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Data Centres: The Prominence of High Voltage Testing

After the success of the previous blog post T&D UK would once again like to thank Karl Sullivan, Operations Director at Optimum Power Services for this article on data centres and their prominence of high voltage testing.

Optimum Power Services are one of the UK's leading providers of generator rental and high voltage testing equipment with over 30 years in the market covering all aspects of power testing.

To contact OPS, Telephone +44 1322 381726 or email to

Optimum Power Services

Data Centres: The Prominence of High Voltage Testing

There has been a huge increase in demand for the power requirements of data centres over the past decade or so; IT services, telecoms, the social media “big boys” and financial and banking sectors all rely emphatically upon the infrastructure of their data centres. Due to their mission critical status it is essential that they all have significant and robust embedded standby generation systems. To minimise the footprint impact of large capacity generator farms the manufacturers have focused on providing high power density solutions, and diesel driven generating sets in excess of 2MVA prime rating are now commonplace.

Pictured: UK Data Centre Testing

Data Centre Testing

This increase in size leads to the inevitable knock on effect of distributing such large amounts of power throughout the site’s electrical infrastructure. The solution has been the move away from low voltage 400V alternators to fitting large prime movers with medium/high voltage alternators, typically of 11,000V. As voltage increases, so current decreases for any given load, and the cross sectional area of conductors required to carry that load diminishes accordingly. The high voltage generation is distributed to site transformers that step down to low voltage at the areas that need it. This has dramatically reduced the amount of cabling or bus bar trunking required to distribute the power around the site.

Optimum Power Services: Data Centres

The switch to high voltage generation:

The move to high voltage generation has resulted in a new challenge to accurate load test data recording. For flexibility of use, the rental load bank industry has always favoured low voltage load banks, utilising containerised packaged step down transformers to convert the high test voltage into the low voltage required by the load bank to operate. Therefore, the incorporated instrumentation fitted to the load bank records the results at low voltage and as such are not entirely representative of the generating set itself, as loses are incurred across the transformer.

Increasingly engineers and consultants are demanding to see the generator tested not only at its rated power factor, but to see results recorded at its rated voltage. Many modern PC-based data capture systems allow for the incorporation of HV monitoring. HV current and voltage transformers can be fitted at the clients’ HV connection point to allow for monitoring of the actual generator output. Where this is not practical they can be fitted at the HV input to the step down transformer, leaving only the negligible loses across the temporary HV cable un-accounted for.

ISO 8528 (BS7698): part 6ISO 8528

As we referred to in our last guest post, both quality standards and the ISO 8528 for engine-driven gen-set testing demand that complete testing is carried out. Professional engineers and consultants have responded by specifying such tests. The equipment, with control, instrumentation, data capture and analysis systems for any voltage are available in the load bank rental industry.

Whilst the industry as a whole may yet to have caught up, there is no doubt that in the near future more tests will be done to ensure that generating sets comply with specification, will accept load in service under a managed maintenance regime, and will operate in an environmentally acceptable way with optimum fuel efficiency and minimum pollution.

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Category:  Electrical Equipment HV

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