Confidential Utility Client — UK Grid Substation
400/33kV 60MVA Transformer Installation & Commissioning
Northern HV delivered full installation and commissioning of a 400/33kV 60MVA power transformer at a UK grid substation. Vacuum oil filling, IEC 61850 protection integration, and energisation on schedule — over 8,000 man-hours without incident.
Client
Confidential Utility Client
Location
UK Grid Substation
Contractor
Northern HV Ltd
Project Overview
Northern HV was appointed to deliver the full installation and commissioning of a 400/33kV 60MVA power transformer as part of a major grid reinforcement scheme. The transformer was a critical element in increasing network capacity and improving supply resilience for a growing industrial and residential demand area.
Our scope covered everything from delivery coordination through to final energisation: transformer positioning, radiator assembly, vacuum oil filling, HV cable terminations, protection and control integration, and comprehensive commissioning. All delivered in accordance with National Grid and DNO standards over a 16-week programme.
The transformer was energised on schedule. Over 8,000 man-hours without incident.
Scope of Works
Transformer Installation
- Delivery coordination and offloading of 60MVA transformer
- Positioning onto prepared foundation and anti-vibration pads
- Radiator bank assembly
- Vacuum oil filling and filtration
- Installation of bushings, conservator, marshalling kiosk, and associated pipework
HV Connections
- Installation of 400kV and 33kV cable sealing ends
- HV cable glanding and termination
- Contact surface preparation and torque verification
Protection & Control
- Protection and control panel installation and wiring
- Differential, REF, Buchholz, PRV, and temperature monitoring integration
- IEC 61850 compliant protection relay configuration
- SCADA system integration
Testing & Commissioning
- Winding resistance tests
- Turns ratio testing (TTR)
- Magnetising current testing
- Insulation resistance and Polarisation Index
- SFRA (Sweep Frequency Response Analysis)
- Oil dielectric strength testing
- Protection relay secondary injection
- End-to-end scheme testing
- Functional SCADA verification
Technical Challenges
Live 400kV Substation Environment
The works took place within an operational 400kV substation. That meant strict coordination with the network control centre, detailed isolation procedures, and no room for error on switching.
We implemented detailed switching schedules, daily permit coordination meetings, and a dedicated SAP liaison throughout. Safe access maintained, no unplanned outages, no disruption to network operations.
Oil Quality and Moisture Control
Transformer oil quality is critical to long-term performance. Moisture ingress or contamination during assembly can significantly reduce asset life and dielectric strength.
We carried out vacuum oil filling and filtration using calibrated processing units. Final oil quality parameters came in well within IEC standards. Moisture content and dissolved gas analysis were verified prior to energisation — no issues.
Fixed Energisation Date
The project had a hard deadline. The energisation date was tied to wider network upgrade milestones, so slipping wasn't an option.
We deployed parallel workstreams for mechanical assembly and protection panel installation, compressing the programme without compromising QA. The transformer was energised on the planned date.
Safety Performance
We delivered over 8,000 man-hours on this project without a single lost-time incident.
Full compliance with CDM Regulations throughout. Detailed Inspection and Test Plans, QA documentation at every stage, and all commissioning results recorded and issued within the final project dossier.
Client witness sign-off completed before energisation.
Project Outcome
The 400/33kV 60MVA transformer was energised on schedule and is now operational, providing increased network capacity, improved voltage stability, and enhanced supply reliability for the region.
The installation future-proofs the local grid infrastructure for continued industrial and residential growth.
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