Unit Protection Testing
Precision Testing for HV and LV Unit Protection Systems
We carry out professional unit protection testing for high voltage and low voltage systems across the UK. Our service ensures that protection schemes work as designed, isolating faults quickly and maintaining system safety.
What Is Unit Protection?
Unit protection is used to detect faults within a defined section of a network such as a transformer, busbar or cable. The system compares current at two or more points and trips instantly if a fault is detected within the protected zone.
We test:
- Differential protection relays
- Transformer and feeder protection
- Restricted earth fault systems
- Busbar protection and interlocking
- Current transformer (CT) matching
- Relay logic and tripping functions
Using precision test equipment, we simulate fault conditions and confirm the correct operation of all unit protection functions.
Commissioning & Maintenance Support
Whether the system is new or in service, our testing validates functionality, ensures compliance and identifies any configuration issues. Every job is followed by a detailed test report and setting verification.
Where Unit Protection Applies
- Substations
- Transformers and switchboards
- Generators and critical feeders
- Industrial and commercial networks
- Renewable energy systems
Frequently Asked Questions
What does unit protection testing involve?
It involves simulating fault conditions and checking that differential or zone-based protection relays trip correctly and isolate the faulted area.
Can you test all major relay types?
Yes. We work with a wide range of protection relays from all major manufacturers and legacy systems.
Is this part of commissioning?
Yes. Unit protection testing is essential during commissioning and also forms part of routine safety checks in critical systems.
Will we get a report?
You will receive a full report including test values, settings and confirmation that the protection scheme operates as required.