Data Centre Gets Diesel Power Backup

Specialist supplier Dieselec Thistle Generators has recently delivered its largest standby generator order since the company was created last year with the acquisition of Thistle Generators by rival firm Dieselec.

Now operating from a new head office in Glasgow, the company is Scotland’s largest distributor of F G Wilson generator sets and a leading specialist in large standby diesel generators. Its most recent project – and its largest to date – was a £3 million+ order for four 11kV, 2.2mVA diesel gensets to a major financial institution in central London.

The generators will provide emergency power for the client’s data centre, located in the heart of the City’s financial district , in the event of a mains failure or other interruption to the mains supply.

Data centres – along with hospitals, supermarkets and other major power users who rely on a continuous electrical  supply – are important customers for Dieselec Thistle Generators.

“Data centres store huge amounts of very valuable and sensitive information” explains Pedro Araujo, solutions director with Dieselec Thistle Generators. “They require extreme resilience in their power infrastructure because if they lose power they can lose millions of pounds in minutes”.

“They’re quite happy to spend £3-4 million to ensure this doesn’t happen”, he adds.

Data centres also require far higher levels of power than most comparable buildings – often having power densities more than 100 times that of a similar-sized office building. Much of the power is required to run the cooling plant which is essential to prevent the computer systems overheating.

Working closely with main contractor Skanska Rashleigh Weatherfoil, Dieselec Thistle Generators assembled the four generators and, in June 2011, subjected them to a continuous load test 48 hours at the company’s 6.5 acre site in Milngavie, Glasgow.

This is the largest and most demanding witnessed test carried out by the company to date and was monitored by representatives of SRW and the client throughout the process. Conducted over a period of four days, the test required each generator to be run at full load for a continuous eight hours while its performance was monitored and recorded.

Once each generator had been tested individually, the four units were then synchronized and run together for another eight hours to deliver a consistent 8mVa of power. This rigorous test procedure was essential to demonstrate that the generators, once installed in their central London location, will be capable of delivering consistent, reliable power to maintain the servers and ancillary equipment.


Each generating set comprises an 11kV Leroy Somer alternator driven by a 16 cylinder Perkins diesel engine. However the test also required substantial temporary equipment including a system of silencers and exhaust flues, 6mVA of reactive load banks to simulate the working load, neutral earth resistors and a five-section 11kV containerised synchronised switchboard built especially for the test.

Dieselec Thistle Generators also assembled four cooling towers, each comprising a pair of electrically-driven fans, to replicate the remote cooling system already in place on the roof of the data centre. “The existing cooling towers are remaining in place, so we had to provide an equivalent system for the live load test” says Mr Araujo.

After successfully completing the load test, the next step was to dismantle the equipment and deliver the generators to London for installation in the data centre.

During decommissioning of the data centre’s five existing generators and installation of the new F G Wilson models, backup power has been supplied by temporary generators supplied by a specialist hire company, located in an adjacent building.

“The client actually bought the building especially” says SRW project manager James Britt. “It is located across the road from the data centre so the power cables were installed underneath the road”. Dieselec Thistle Generators, although not involved with the supply of these generators, has supplied switchgear to synchronise them.

Removing and replacing the old generators was a logistical challenge, given the congested location and lack of access to the city centre site. The standby generators are housed in a third-level basement car park adjacent to the building and the only way of getting them in and out was to dig through from the surface.

“We cut a 2.5 m x 4.0 m hole in the car park slab and lifted the existing generators out” explains Mr Araujo. “Then we had to install the four new generators via the same route” he says. Because the new generators measure 6.5 m in length, it was necessary to dismantle them into their four basic components: engine, alternator, base-frame and heat exchanger. Each generator was then re-assembled in situ.

The five existing generators, although no longer suitable for this client, are less than 30 years old and have notched up no more than 8,000 hours – “they’re barely used” according to Mr Araujo. Hence they have been sold to another customer along with the four cooling towers originally  bought for the witnessed load test at Dieselec’s headquarters.

Main contractor SRW’s ‘Mission Critical’ team specialises in the construction and upgrade of data centres and similar projects which require highly resilient electrical and mechanical systems. In particular, the team has gained a reputation for “live working” which requires (as in this case) the work to be carried out while the building remains fully occupied.

“The data centre has remained fully operational throughout the project and so most of our work has had to be done out-of-hours – late and night and at weekends” explains James Britt.

The project, which was conceived over four years ago, will have taken 12 months to deliver when it is handed over to the client in November 2011. Dieselec Thistle Generators has negotiated an on-going 25 year maintenance contract with the end-user.


Dieselec Thistle Generators is one of the UK’s leading specialist suppliers of diesel generators with over 90 per cent of the Scottish market and a rapidly growing market share in England and Wales.

The company was created with the merger in December 2010 of Dieselec Generators Ltd and Thistle Generators Ltd. The company moved to a new 6.3 acre head office facility in Milngavie, near Glasgow, in January 2011.

The Milngavie facility retains a £500,000 stock of generators from 6 to 800 kVA plus ancillary equipment. Bespoke generating sets up to 2,500 kV can be supplied.

Activities in London and the South East are supported by the company’s central London office, and newly opened depot in Dartford.