STANDBY GENERATORS GEOFF HALLIDAY – BUSINESS CONSULTANT, WB POWER SERVICES LTD, UK
Common specification clarifications in focus
Geoff Halliday, business consultant for WB Power Services Ltd (now part of Rehlko), highlights the most common specification clarifications and derogations that arise when installing and operating standby generators in healthcare settings.
We have a long history of supplying standby generation solutions to the NHS/Healthcare sector, and during that time we have installed large number of generating sets – amassing a significant experience base along the way. The various Health Technical Memorandum (HTM) are in place to give comprehensive advice and guidance on the design, installation, and operation of specialised building and engineering technology used in the delivery of healthcare. However, there are areas of the HTM relating to aspects of a generator installation which can be viewed to be at variance with commercially available products, highlighting anomalies between the HTM and BS EN ISO Standards that sometimes do not reflect or consider recent changes legislation or market driven product evolution.
In this article, we consider some of the
most common specification clarifications sought by WB Power Services and adopted derogations. For ease of use we have identified each of these by using the HTM 06-01 (2017) reference section.
9.38 Short-term parallel operation/ 9.39 Long-term parallel operation Clarification: Generating set control panels are available to manage both generator incoming breaker (switchboard) control requirements for short-term or long term parallel with the DNO Mains supply, offering a range of facilities ranging from soft mains return, ‘live’ load testing to peak lopping and STOR.
Plantroom installation of 2000kVA generating sets.
Short term mains synchronising for purposes of soft mains return is a basic standby power application and as such does not require exhaust emissions abatement it being an ‘Excluded Standby Generator’ within the bounds of MCPD regulations. Longer terms mains synchronising – depending on the operational requirements – may be subject to the requirements of the MCPD regulations (all subject to site specific EA and regional review).
Geoff Halliday Geoff Halliday started his career as an apprentice working for
Square D (later part of Schneider) before moving into the critical power sector, where he has now worked for over 40 years, splitting that time equally between the UPS and standby diesel generation sectors. During this period, Geoff has held several
roles ranging from customer service engineer, project manager, technical director, sales director, through to managing director. Drawing on his management skills, product knowledge, and the
vast application experience amassed throughout his career, Geoff now enjoys sharing his knowledge with others.
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9.73 Overload Rating Clarification: A Prime Rated Power (PRP – ISO8528) generator will PRP meet the rating as required in HTM06-01. A PRP rated set offers a 10 per cent overload for one in every 12-hours as set out in HTM-06.
9.74 Category of Load Acceptance Clarification: Generating sets sold within Europe are designed to meet the requirements of BS EN ISO8528 and offer transient performance in compliance with the range G1-G4 (ISO8528) and associated levels of first step load acceptance. G2 performance is aligned with HTM 06- 01 for Category-3 / 60 per cent load acceptance at the PRP rating but frequency recovery will be within five seconds (as per G2 ISO8528). Note: This section should be read in
conjunction with HTM section 9.75 as gross oversizing of the generator is necessary to achieve category 2 and 1. Performance at these levels is available typically by utilising a generating set with a larger engine capacity. Minimum operating load levels must be considered.
IFHE DIGEST 2026
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