UK Government, Scotland

The Challenge – The existing standby provision had reached the end of its operational life and no longer met the client’s resilience requirements. The new installation needed to deliver multi-set resilience, full emissions compliance, long-term fuel quality assurance, and the ability to test on live site load without interrupting normal operations.

Our Solution

Generator Plant

• Three 500 kVA, 400V containerised diesel generators — Marapco MP500E sets with Perkins engines and Leroy-Somer alternators. Each is housed in an acoustic-rated container specified by AC Automation, including motor-operated dampers, bunding, internal lighting and power, and a baseframe fuel tank. The sets can operate independently or in parallel, with automatic starting on mains failure.

Control System

• AC Automation designed and supplied a complete ComAp-based control architecture, providing full supervisory functionality across the generator plant. The system includes:
• 3 × InteliGen 1000 generator controllers
• InteliMains supervisory controller
• InteliPro mains protection relay
• InteliVision HMI for operator interface

The Master Control System manages synchronisation of the three generators for parallel operation, load sharing and demand management, controlled synchronisation with the HV mains via the step-up transformer (enabling both no-break mains return and on-load testing without interrupting site supply), LV feeder and HV breaker control, and full system protection, monitoring, alarming, and logging.

Emissions Control

• Each generator is fitted with a Selective Catalytic Reduction (SCR) system, supported by a 2,500-litre urea storage tank, master SCR panel, and dedicated urea control panel. Urea dosing is automatically adjusted to generator load and exhaust conditions, reducing NOx emissions in line with current standards.

Fuel System

• 9,000-litre Convault bulk fuel tank — fire-rated, blast-proof, and bunded
• Centralised fuel pump cabinet housing dual transfer pumps per generator (with automatic duty/standby switching), control panel, leak detection, and ATEX-rated fuel level monitoring
• Underground UPP double-wall fuel pipework with LAD-R leak detection on both inner and outer skins
• WASP fuel polishing system to maintain long-term diesel quality

Electrical Infrastructure and DNO Liaison

• The new generator plant connects to the upgraded HV network via a step-up transformer, with the three generators synchronising both with each other and with the HV mains supply. This enables seamless load transfer in either direction and full on-load testing without site disruption. AC Automation also liaised directly with SSEN to secure the connection agreement.

The Outcome – Delivered in 2025, the system provides the client with a fully automated, emissions-compliant standby solution. Key benefits include resilient multi-set operation, mains-parallel testing without site disruption, long-term fuel quality assurance, and a single intuitive control interface for day-to-day operation.