63 and 225 kV substations
Protection relay testing
Differential protection and on-load tap changers. Testing carried out with Volt Expertise.
Service
Protection, tap changer and automation testing
Relay configuration from the protection plan, injection testing, testing of on-load tap changers and substation automation, test reports.
Testing verifies the complete chain, from the measured quantity to the opening of the circuit-breaker. We check that the settings are actually loaded in the relay, that the CTs are wired the right way round and that the trip command reaches the coil.
Protection relays
We work on all generations of relays, electromechanical, static and numerical. The ranges we encounter most often are Schneider Electric Sepam and Easergy P3, MiCOM, Siemens SIPROTEC 4 and 5, ABB / Hitachi Energy Relion (615, 620, 670 series) and SEL. Configuration is done with the manufacturers' software, from the settings schedule.
The functions tested are phase and earth overcurrent (50/51, 50N/51N), directional (67, 67N), transformer, busbar and line differential (87T, 87B, 87L), distance (21), voltage and frequency (27/59, 81), breaker failure (50BF), auto-recloser (79) and synchronism check (25). In digital substations, we also verify IEC 61850 (GOOSE) exchanges between devices.
On-load tap changers and voltage control
The on-load tap changer (OLTC) is the only part of a transformer that switches under load. We test the tap changer and its drive: direction of operation, electrical and mechanical end stops, position indication and remote signalling, local and remote control, operation counter, the tap changer compartment's own protection.
We then test the voltage regulator, with the setpoint, deadband, first and second operation time delays, line drop compensation, undervoltage and overcurrent blocking, and parallel operation of several transformers (master / follower or minimum circulating current). A poorly set regulator hunts and operates constantly, which wears the tap changer.
Automation and control loops
We test source transfer and restoration, load shedding on frequency or load, auto-reclosing, intertripping between substations, interlocking and capacitor bank control. For power plants and storage, we also test the power plant controller (voltage, reactive power and cos φ control, power limitation) and its response to the network operator's setpoints.
01What we do
Protection
- Configuration from the settings schedule
- Secondary injection: thresholds, times, curves
- Primary injection, CT polarity
- Trip chains through to the circuit-breaker
- IEC 61850 exchanges
On-load tap changers
- Direction of operation, end stops, positions
- Local and remote control
- Tap changer protection
- Regulator: deadband, T1 / T2, line drop compensation, blocking
- Parallel operation
Automation
- Source transfer, load shedding
- Auto-recloser, synchronism check
- Intertripping, interlocking
- Capacitor bank control
- Renewable and storage power plant controller
02Examples
03Our offer
Usual content of an offer for this type of assignment. The exact scope, deliverables and price are set in the quotation.
- Package 1Preparation
Settings schedule, diagrams, test sheets per function.
- Package 2Configuration
Files loaded, reviewed and compared with the schedule.
- Package 3Testing
Injection, trip chains, tap changers and regulators, automation, according to the scope.
- Package 4Test reports
Results, deviations, punch-list items closed or still open.
04How we work
- 01Preparation
Settings schedule, diagrams, test sheets per function.
- 02Configuration
Files loaded, reviewed, compared with the schedule.
- 03Injection testing
Thresholds, times, curves, logic, trip chains.
- 04Functional testing
Tap changers, regulators, automation, under real conditions where possible.
- 05Test reports
Results, deviations, punch-list items closed or still open.
05References
Industrial site
Protection coordination and relay verification
MV protection coordination and on-site check of the settings.
06Frequently asked questions
Without a protection plan?
We can check the existing settings, but we recommend an up-to-date protection plan first.
Do you work on old relays?
Yes. Electromechanical and static relays can also be tested, with suitable methods. Their replacement is discussed in light of the results.
Where do you work?
Throughout France, usually during plant shutdowns.