Supplying mission critical power to data centres

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For any data centre, a reliable power supply is, of course, key. Without electrical power, transactions simply cannot take place and the cost of these lost transactions can escalate to many millions of pounds per hour. Clint Noble of Finning Power Systems explains

In many cases, the electricity supply network was not built, nor is maintained with a view to the levels of consequential loss that may be seen in a data centre. As a result some alternative means of power supply is a must.

Finning Power Systems (Finning) is a provider of mission critical power solutions to the data centre market. Alongside emergency generator sets for standby power, the company also provides a range of battery and flywheel UPS systems to protect critical data in the event of mains failure, together with control systems for cost-efficient monitoring of system parameters.

A recent example of this is the back-up power installation Finning supplied to Digital Realty’s (DLR) flagship datacenter in Chessington, South West London.

Interest in the new Chessington facility is high, with a large proportion of the data space leased already. Ensuring that DLR provides the high efficiency levels required to meet this customer demand therefore requires a highly dependable emergency power infrastructure.

Efficient design

The site includes two 1,440 kW Turn-Key Flex data halls, where Finning has supplied six Cat® 3512BHD generator sets in a pod arrangement. Each pod has three generators installed on an N+1 basis producing a combined power (N) of 3000 KWe.

The new facility offers the latest advancements in efficient datacentre design, enabling very effective Power Ulitisation Efficiency (PUE) and 99.999% uptime and above, as well as innovative cooling methods, including outside air free-cooling chillers operating at enhanced temperatures for greater part load and overall power efficiency.

As with any data centre, power availability is paramount and DLR has therefore partnered with Finning once more, thanks to an installation track record of nearly 30 MW at the company’s existing sites in the UK and France. The company’s proven Cat product offer, installed in thousands of installations worldwide, together with its bespoke engineering, quality control standards and installation expertise were also important factors in DLR’s choice of supplier.

Each pod contains three 1875 kVA standby diesel generator sets with operator control panel, together with self-contained fuel system and remote cooling.

Reducing noise pollution is particularly important, so Finning engineered the package with an air inlet and discharge system and exhaust gas silencers all sized to achieve levels no greater than 70 dBA within a one-metre radius and with two generator sets running.

DLR has made significant investment in the facility’s cooling infrastructure and so the Finning team ensured that all of the power equipment installed was optimised to reduce parasitic heat transfer; such as jacketing the heat exchanger located in the plant room to minimise heat losses. Each generator set also has its own remote cooler, heat exchanger and circulation pump.

A purpose-built fuel system for each pod consists of a 25,000-litre day tank serving three, smaller 600 litre tanks acting as a dedicated fill point for each generator. The feed to each day tank is supported by a dedicated duty, standby fuel pump housed in the end enclosure of each above-ground bulk tank.

Specifying the right solution

Specifying the right solution for a data centre’s mission critical power takes careful planning as installations can vary considerably between applications.

Finning offers a number of solutions, including the newly-rated Cat C175-20, which provides up to 3.2MW of power in the smallest footprint of any single high-speed diesel generator set available on the market.

This increased power density is a key benefit for standby power for mission-critical power installations requiring larger safety loads. It can reduce the ancillary equipment required, particularly when integrated into a Finning turnkey solution containing Cat switchgear, uninterruptible power supply (UPS), control systems and noise limiting acoustics, resulting in a more cost-effective installation.

The C175-20 can also be used to generate prime power for remote work sites and in peak shaving applications.

Reduced operating costs

The new generator reduces operating costs by extending maintenance intervals. For prime and continuous power applications, oil change intervals are every 600 hours. For standby generator sets, a three-year oil change interval option is available. Equipment overhaul periods are also extended to 22,000 for 60 Hz units and 27,000 hours for 50 Hz units.

High reliability

The C175-20 package is built on the proven C175-16 platform, which has demonstrated its reliability in Cat machines and other power generation applications since 2008. A ridged engine wiring harness protects critical engine circuits from damage and redundant control wiring minimises the impact of electrical faults.

Sustainable option

Certified to EPA Stationary Emergency Tier 2 emissions’ limits for 60Hz applications the C175-20 is a sustainable option for power generation. In addition a wide range of Cat after treatment solutions are available to reduce oxides of nitrogen (NOx), hydrocarbons and particulate matter.

The unit can also run on a range of biodiesels and is available with a low fuel consumption version to further reduce emissions and operating costs.

Improved engine breathing design allows for a greater amount of cooler air to circulate through the engine, which combined with high-pressure fuel injection enables more efficient combustions, resulting in lower fuel consumption.

The C175-20 is also available with a full range of factory designed and tested attachments or as a complete containerised package from Finning Power Systems to reduce installation costs and optimise performance.

33% more efficient

The Cat 3516C-HD generator set from Finning offers up to 33% more power per square metre for mission critical installations than other conventional units.

The new unit is available with both a 2750 kVA standby rating and a 2500 kVA prime power rating and has been purpose designed to provide high performance and excellent fuel economy. The 3516C-HD delivers a highly cost-effective option for operators requiring a proven, Cat generator set within this power range and extends Finning’s engine portfolio further, to provide a complete range of engine ratings for data centres.

Installation and operating costs have been considered at every stage of the design to ensure lowest cost of ownership. With a 25% smaller footprint than other comparable engines, the Cat 3516C-HD package can be integrated easily in to existing data centres, saving valuable floor space to enable future expansion. Weighing less than 21,500 Kg, installation and transportation costs are also reduced, thanks to a lighter, smaller design, which includes two generator bearings, for better stability and alignment.

The engine can operate at ambient temperatures up to 50 oC at full power, which is up to ten degrees higher than comparable units and features a lower cost exhaust system and improved motor starting capability, to help reduce the amount of on-site power required.

The unit is available as a complete package for simpler installation, incorporating Caterpillar’s proven four-stroke, water-cooled diesel engine, and the compact SR5 generator, matched to engine output and performance and featuring a low power and friction loss design.

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