Innovative circuit breakers for Oxford's largest hospital
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ELECTRICAL RESILIENCE
Innovative circuit breakers
for Oxford’s largest hospital
Mike Porter, Business Development Manager at electrical distribution and control specialist, Electrical
Distribution Solutions, who has ‘a wealth of knowledge on switchgear’ gained throughout a lengthy
electrical career, describes a project undertaken in very rapid time, with minimal disruption, at Oxford’s
John Radcliffe Hospital, to replace obsolete low voltage air circuit breakers with retrofit variants, which will
significantly extend the life of the existing switchboard at a cost of under one-third of a new switchboard.
Oxford University Hospitals NHS Electrical switchboard issue reliability and continuity of supply with
Foundation Trust provides a wide range The power required by the Trust’s largest obsolete switchgear.
of clinical and specialist services – which acute healthcare facility, the John Radcliffe
include cardiac, cancer, musculoskeletal Hospital in Headington – Oxfordshire’s Space constraints
and neurological rehabilitation, as well main Accident and Emergency site, which Consideration was given to replacement
as medical education, training, and provides acute medical and surgical of the complete switchboard, but with
research. It says that ‘collaboration with services including trauma, intensive care, space limited, and with the Trust not
the University of Oxford underpins and cardiothoracic services – is distributed willing to see the electrical distribution
the quality of the care we provide to at 11 kV through a network of high voltage system put at risk – a potential scenario
patients’. cables to four sub-stations, where it is being one transformer isolated in order
As of the end of 2020 the Trust transformed down to 415 V for further to install a new low voltage switchboard,
had 1,133 beds – which included 946 distribution into the hospital buildings. the customer looked for an alternative,
general and acute beds, 79 critical care Each transformer feeds a main low innovative solution. I thus met with Mark
beds, 18 for rehabilitation, and 90 for voltage distribution switchboard, which Martin, the Trust’s Operational Estates
children. With 58 inpatient areas, 48 were manufactured by Ottermill, which project manager, to discuss and gain an
operating theatres, and 11,904 staff at ceased trading many years ago. The understanding of the operational issues
that point, the Trust has over 1.5 million switchboards date back to 1974 and are and constraints faced by the hospital.
patient contacts annually, and serves now obsolete. The unavailability of spares, Upon completion of a joint site visit,
the growing populations of Oxfordshire, and the low voltage air circuit breakers Electrical Distribution Solutions proposed
Buckinghamshire, West Berkshire, becoming problematic, gave rise to major and tendered a solution.
Northamptonshire, and Wiltshire, concerns over the reliability of supply, and The joint site visit between the hospital
although patients come from even further the Trust’s Estates Department faced Estates Department and Electrical
afield for specialist procedures. the dilemma of how to maintain Distribution Solutions revealed that the
Oxford’s John Radcliffe Hospital in
Headington is the Oxford University
Hospitals NHS Foundation Trust’s
largest hospital, and Oxfordshire’s
main accident and emergency site.
February 2022 Health Estate Journal 59
ELECTRICAL RESILIENCE
The original Ottermill low voltage air circuit breaker in its withdrawn An EDS retrofit low voltage air circuit breaker
position (left), and an EDS Ottermill retrofit such circuit breaker (right). replacing the Ottermill type OMA24 bus-section.
‘‘
fixed portion of the switchboards was Of equal importance when undertaking
in very good condition, and suitable for
It was necessary to this work on the John Radcliffe Hospital
continued operation. undertake tests to distribution system was that, where
With-ever increasing financial pressure possible, we should maintain the N+1
facing Oxford University Hospitals NHS ensure that both requirements as set out in Health
Foundation Trust, Electrical Distribution transformers were in Technical Memorandum 06-01: Electrical
Solutions was able to offer an innovative, services supply and distribution (2017
technically sound, and cost-effective phase edition).
retrofit solution. As the project involved the
device which affords much improved replacement of incomers and associated
Extending existing switchboard’s life functionality. It allows enhanced grading bus couplers, in theory both transformers
The proposed solution was to replace the with upstream and downstream protection being of the same phase rotation would
obsolete low voltage air circuit breakers devices, along with remote closing, allow the bus coupler to be closed
with retrofit low voltage air circuit opening functionality, and metering before the incomer is opened. The John
breakers, which would significantly extend facilities, which can be incorporated into Radcliffe Hospital distribution network
the life of the existing switchboard at a the Trust’s building management scheme. was operated with both incomers
cost of much less than one third of a new The project at John Radcliffe Hospital closed and the bus coupler open. This
switchboard. involved the replacement of 14 low voltage has been the case for many years. In
The retrofit solution negates the breakers, as follows: order to utilise this arrangement, it was
requirement for complex planning, civil, n Four Ottermill OMA 12 50 kA, 1250 A, necessary to undertake tests to ensure
cabling, and cable jointing/termination, incoming ACBs. that both transformers were in phase.
and extended periods of time where the n Two Ottermill OMA 12 50 kA, 1250 A, Having undertaken testing and proven
hospital electrical distribution system Bus coupler ACBs. that the transformers associated with
would be at risk. n Five Ottermill OMA 25 50 kA, 2500 A, each switchboard were in phase, it was
The Electrical Distribution Solutions incoming ACBs. now clear that the system’s N+1 status
retrofit low voltage air circuit breaker n Four Ottermill OMA 25 50 kA, 2500 A could be maintained throughout the
utilises a modern air circuit breaker which bus coupler ACBs. installation work, thereby maintaining
has been engineered to directly fit in place continuity of supplies to all parts of the
of the old low voltage air circuit breakers Installation considerations hospital – to the extent that very few, if
without, in most cases, the requirement for As with undertaking any work on any, hospital staff were even aware of
a busbar outage. All interface points, such an electrical distribution system, of the major work being undertaken on the
as contacts and interlocks, are identical paramount importance is health and electrical distribution system. Thanks
and operate the same way as the old safety. Guidance for electrical compliance to Mark Martin and his team, all Permits
circuit breaker. The retrofit circuit breakers in the NHS is the HTM 06-02: Electrical to Work and Sanctions to Test were
incorporate a modern intelligent electronic safety guidance for low voltage systems. issued promptly and very professionally,
60 Health Estate Journal February 2022
ELECTRICAL RESILIENCE
allowing the entire works to be
completed in one eight-hour shift. Mike Porter
Getting equipment to site Mike Porter, appointed on a part-time basis as
One of the more mundane issues to be Business Development Manager for Electrical
considered – given that the John Radcliffe Distribution Solutions in February 2021,
Hospital is an extremely busy acute brought to the role ‘a wealth of knowledge on
healthcare facility, with heavy staff, patient, switchgear’ and many UK and overseas contacts.
and visitor traffic – was the delivery of He says of his career to date: “On leaving
the equipment to site and to the different school, I secured an apprenticeship with South
substations. To mitigate any risk associated Wales Switchgear as an electrical technician,
with transporting and lifting of large plant, gained a sound grounding in engineering
it was deemed best practice to deliver the practice, and considerable knowledge of the
equipment to site in the silent hours. principles of High Voltage switchgear. On
The Trust’s Mark Martin said of the completing my apprenticeship, I worked as an
project: “I have completed similar electrical technician in the Test and Certification
replacement projects in the past, in Department at South Wales Switchgear, followed by a three-year spell as a Design
previous roles. The amalgamated team of Draughtsman in the Switchgear Design Department – where I was involved with
Electrical Distribution Solutions and SPE the detailed design of switchgear, overhead stack-bridge dampers.”
Energy worked flawlessly, and proved one His next role was as Senior Electrical Authorised Person responsible for the high
of the best teams to work with. On the voltage distribution network at RAF St Athan in the Vale of Glamorgan, where he
day of the changeovers the combined gained practical experience in the installation, maintenance, testing, and operation,
resources, along with my hospital team, of HV switchgear and transformers installed in a distribution network, including
worked tirelessly together to ensure that switching, and issuing of Permits to Work and Sanctions to Test.
safe working and supplies to all areas were He later moved into business development in the switchgear industry, as Area
uninterrupted. We also maintained our Sales Manager for the South Wales and the South-West with GEC Alsthom. On the
N+1 resilience at all times. The project’s ’s sale of GEC Alsthom and a re-organisation, he became Key Account Manager with
successful completion also gives us the AREVA responsible for South Wales Electricity Board, Southwestern Electricity
ability going forward to parallel up our Board, Midlands Electricity Board, East Midlands Electricity Board, Guernsey
transformers, so we can ‘make before Electricity, and Jersey Electricity. His next role was as a National key Account
break’ if we need to switch to alternative Manager for the rail sector, which included Network Rail, London Underground, and
supplies. The technical ability of all staff all consultants and contractors involved in the electrification of the rail network. He
was exceptional, and the installation was said: “My last full-time role was as Sales Director for switchgear designer, developer,
completed within a single day.” and manufacturer, SPE Energy, responsible for both UK and export sales.”
February 2022 Health Estate Journal 61
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