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The CHP Generation Game: Staying Compliant With G59

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As Combined Heat and Power (CHP) systems continue to grow in popularity, Edward Garside, Project Engineer at Bosch Commercial and Industrial, explains how to stay compliant with power generation legislation.

“As a CHP module is effectively a power supply embedded within a building that is connected to the national grid, there are parameters surrounding its safe installation. Set out by the Energy Networks Association, G59 is a set of provisions ensuring the module will operate in a safe manner compatible with the National Grid.

“To combat inadequacies in the electrical infrastructure, G59 regulates generator applications so they cannot be connected to the grid without the knowledge and permission of the local electricity authority.

“The legislation, specifically ‘G59/3’, is programmed into a device called a G59 protection relay which has the ability to automatically disconnect the CHP unit in the event of a power cut or fault on the network, and as such keeps the wider supply safe and secure. Any generator rated above 16 Amps per phase and connected to the national grid must be fitted with a G59 relay in order to comply with G59/3 legislation.

“Put simply, the protection relay monitors the quality and stability of the mains electricity in accordance with the District Network Operator (DNO) and assesses the voltage, frequency, and phase angle.  Should any of these areas go outside the predetermined limits, the relay will cause a protective circuit breaker to open and thereby disconnecting the generator from the grid.

DNO requirements

“As part of the connection process of a CHP module or power generation source to the National Grid, there are a number of aspects the DNO will consider. The result feeds into what is called a G59 Parallel Running Agreement document, which permits the operator of a CHP system to generate electricity with the National Grid. It is important to remember that this agreement is needed regardless of whether or not a generator will export electricity.

“Often the DNO will wish to see proof of G59/3 compliance in the form of a witness test, whereby a representative of the DNO, a G59 test engineer and CHP engineer attend the site and to observe the testing of the G59 relay.

Importance of pre-planning

“After a G59 application has been submitted the DNO has up to 45 working days to send out the results of their network study and provide a formal quotation for any fees required. If the DNO requests a G59 witness test, this will have to be booked following payment of any fees listed on their quotation. They typically attend the site for a witness test within a few weeks of notice however, there is no set notice period and with limited availability of staff it is advisable to book well in advance.

“There can be a lot to take into account when installing CHP modules, but by working closely with those involved in the supply and installation of a CHP system, compliance with regulations such as G59 needn’t be a mystery.”

For more information on Bosch Commercial and Industrial and its market-leading range of CHP systems, visit www.bosch-industrial.co.uk or call 0330 123 3004. Alternatively, follow Bosch Commercial and Industrial on Twitter (@BoschHeating_UK) and LinkedIn (Bosch Commercial and Industrial UK).


Press Enquiries to:

Rob Jones / Liz Fisher
Rob@wpragency.co.uk / Liz@wpragency.co.uk
Tel: 0121 456 3004

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Guest Monday, 18 February 2019