Protection Relay Testing & Commissioning
Functional testing, setting and final verification of overcurrent, distance, differential and transformer relays.
Protective relays are the most important line of defence in a substation: a wrong setting or an incomplete logic can mean a wide-area outage or damage to expensive equipment. At ENP, relay testing is more than "inject and record a number". Our process starts with the coordination study and setting verification, continues with functional, logic and trip-circuit testing, and ends with an official report and the final as-left setting file.
Relays we cover
| Relay type | ANSI code | Typical application |
|---|---|---|
| Phase & earth overcurrent | 50 / 51 / 50N / 51N | Feeders, transformers and motors |
| Directional overcurrent | 67 / 67N | Ring networks and parallel feeders |
| Distance | 21 / 21N | Transmission and sub-transmission lines (63, 132, 230, 400 kV) |
| Transformer differential | 87T | Main protection of power transformers |
| Line / bus / generator / motor differential | 87L / 87B / 87G / 87M | Unit protection with defined zones |
| Transformer auxiliary protection | 49 / 64REF / 63 / 26 / 71 / 90 | Thermal, restricted earth fault, Buchholz, temperature, oil level, tap changer |
| Voltage & frequency | 27 / 59 / 59N / 81 | Under/over-voltage, neutral displacement, frequency |
| Auto-reclose & synchro-check | 79 / 25 | Automatic reclosing and synchronism check |
| Breaker failure & lockout | 50BF / 86 | Back-up tripping and circuit lockout |
Common ANSI device numbers
| ANSI | Function | Description |
|---|---|---|
| 21 / 21N | Distance (phase / ground) | Phase and ground distance protection |
| 25 | Synchro-check | Synchronism check before closing a breaker |
| 27 | Undervoltage | Voltage drop |
| 32 | Directional / reverse power | Directional and reverse power |
| 37 | Undercurrent / underpower | Loss of load or power |
| 40 | Loss of excitation | Generator field failure |
| 46 | Negative sequence overcurrent | Load unbalance |
| 47 | Phase sequence voltage | Voltage sequence and unbalance |
| 48 / 51LR | Incomplete sequence / locked rotor | Motor long start and stall |
| 49 | Thermal overload | Thermal protection |
| 50 / 51 | Instantaneous / time overcurrent | Phase overcurrent |
| 50N/G / 51N/G | Earth fault (inst. / time) | Earth-fault protection |
| 50BF | Breaker failure | Breaker failure protection |
| 59 / 59N | Overvoltage / residual overvoltage | Overvoltage and neutral displacement |
| 60 | Voltage / VT supervision | VT fuse-failure supervision |
| 63 | Pressure / Buchholz | Transformer gas and pressure relay |
| 64REF | Restricted earth fault | Transformer restricted earth fault |
| 66 | Starts per hour | Motor start limitation |
| 67 / 67N | Directional overcurrent / earth fault | Directional protection |
| 68 / 78 | Power swing / out-of-step | Power swing blocking and out-of-step |
| 74TC | Trip circuit supervision | Trip circuit health monitoring |
| 79 | Auto-reclose | Automatic reclosing |
| 81U / 81O / 81R | Under / over frequency, df/dt | Frequency protection |
| 85 | Communication-aided protection | Teleprotection schemes |
| 86 | Lockout | Lockout relay |
| 87B / 87T / 87G / 87L / 87M | Differential (bus / transformer / generator / line / motor) | Unit differential protection |
| 90 | Voltage regulation | Voltage and tap-changer control |
| 94 | Tripping / trip-free | Tripping relay |
Brands and families common in Iranian substations
| Brand | Families (examples) | Typical use | Setting software |
|---|---|---|---|
| Siemens | SIPROTEC 4: 7SJ61/62/63/64, 7SA52/522/6, 7UT61/63, 7SD52/61, 7SS52, 7UM62 — SIPROTEC 5: 7SJ82/85, 7SA86/87, 7UT82/85/86/87, 7SD82/86/87, 7SL86/87 — SIPROTEC Compact: 7SJ80, 7SK80 — Reyrolle 7SR | MV feeders, distance, transformer and line differential, busbar, generator | DIGSI 4 / DIGSI 5 / Reydisp |
| Schneider Electric | Sepam series 20/40/60/80 — Easergy P3 / P5 — MiCOM Agile (P14x, P44x, P54x, P64x) | MV feeders, transformers, motors, distance and differential | SFT2841 / SFT2885 / Easergy Pro / MiCOM S1 Agile |
| GE (Multilin / Grid Solutions) | 750/760, 350/345/339, F650/F60/F35, T60/T35, D60, L90, B30/B90, G60, M60, 469 | Feeders, transformers, lines, buses, generators and motors | EnerVista UR Setup / EnerVista 650 / SR3 Setup |
| ABB / Hitachi Energy | Relion: REF615/620/630, RET615/620/670, REM615/620, REL670/650, RED670, REB670, REG670 — legacy: SPAJ, SPAA, SPAD, REL316/511, RADHD | MV feeders, transformers, motors, lines and buses | PCM600 / PCM |
| SEL | SEL-351, 311C/311L, 387, 487, 751, 710, 787, 421 | Oil & gas, petrochemical and industrial networks | AcSELerator QuickSet |
| Areva / Alstom (MiCOM) | MiCOM P12x/P13x/P14x, P44x, P54x, P63x/P64x, P74x — legacy: K series and MCGG | Older transmission and distribution substations | MiCOM S1 Agile / S1 Studio |
| Toshiba / Mitsubishi | GRD, GRL, GRT — MELPRO | Power plants and older substations | Manufacturer software for each model |
| NR Electric / Sifang | PCS-9xxx, CSC-xxx | Some recent projects | PCS-Explorer / manufacturer software |
The list shows examples of the most common models and is not exhaustive. If your relay is not listed, please contact us anyway.
Relays in LV and MV substations
| Voltage level | Typical devices and relays | Key tests |
|---|---|---|
| Low voltage LV (400 / 690 V) | Trip units of air and moulded-case breakers (Schneider Micrologic, Siemens ETU, ABB Ekip/PR), motor protection (Siemens SIMOCODE, Schneider TeSys T), earth-leakage relays | LR (overload), SD (short-time), I (instantaneous) and G (ground) tests with a test kit or primary injection, earth-leakage test, trip-circuit test |
| Medium voltage MV (6.6 / 11 / 20 / 33 kV) | Feeder, transformer, motor and capacitor relays (Sepam, Easergy, REF615, 7SJ, MiCOM P12x/P14x, GE 350/750, SEL-751) | Overcurrent and earth fault, directional, auto-reclose, panel logic and interlocks, trip and breaker-control circuits |
| High voltage HV (63 / 132 / 230 / 400 kV) | Distance, line / transformer / bus differential, breaker failure (7SA, REL670, P44x, D60, 7UT, RET670, 7SS52, REB670) | Impedance characteristic, zones and teleprotection, differential stability, end-to-end test with GPS synchronization |
Relay settings
Settings must come from the short-circuit and protection coordination study. We receive the settings from the consultant or operator, load them into the relay and verify every parameter one by one, not only what is visible on the relay display. Typically checked and recorded:
- CT and VT ratios, secondary rated current (1 A / 5 A), CT polarity and phase sequence
- Pickup values, time multiplier (TMS / time dial) and curve type
- Setting groups (1 to 4) and group-change conditions
- Binary I/O mapping, LEDs and trip matrix
- Programmable logic, interlocks and auto-reclose
- Communication parameters: IP, IEC 61850, IEC 60870-5-103, Modbus, DNP3 and time sync (SNTP / IRIG-B)
- Passwords, access levels and file versions (As-Found and As-Left)
Standard inverse-time curves (IEC 60255-151)
Formula:
t = TMS × k / ((I / Is)^α − 1)
| Curve | k | α |
|---|---|---|
| Standard Inverse (SI / NI) | 0.14 | 0.02 |
| Very Inverse (VI) | 13.5 | 1 |
| Extremely Inverse (EI) | 80 | 2 |
| Long-Time Inverse (LTI) | 120 | 1 |
Typical setting values (for orientation only)
| Protection | Parameter | Typical value |
|---|---|---|
| Phase overcurrent (51) | Pickup | 110 to 130 % of maximum load current |
| Earth fault (51N) | Pickup | 10 to 20 % of CT rated current (depends on system earthing) |
| Distance (21) | Zone 1 / Zone 2 / Zone 3 | 80–85 % of line / 120 % of line or line + 50 % of adjacent line / longer back-up zone |
| Transformer differential (87T) | Minimum pickup / slope | 0.2 to 0.3 In / dual slope, e.g. 25 and 50 % |
| Transformer differential (87T) | Harmonic restraint | 2nd harmonic about 15–20 %, 5th about 20–35 % |
| Over / undervoltage (59 / 27) | Pickup | About 110–115 % and 80–90 % of rated voltage |
Final values always come from the project's coordination study and the manufacturer's manual; the table above is for orientation only.
Testing method
- Initial inspection: panel condition, wiring, terminals, DC supply, CT and VT circuits and earthing
- Three-phase secondary injection with calibrated equipment (Omicron, Megger, Doble or equivalent) and recorded test files
- Pickup / drop-off tests and timing against the curve
- Distance characteristic on the impedance plane, directional checks, differential bias characteristic, harmonic restraint and stability on external faults
- Logic, interlock, auto-reclose and breaker-failure tests
- Complete trip chain to the circuit breaker, close and trip commands, trip-circuit supervision
- Signal tests to SCADA (point-to-point) and GOOSE messages in IEC 61850
- End-to-end tests for line differential and teleprotection with GPS synchronization
- On-load checks after energization: current and voltage direction and angle, differential balance
Deliverables
- Official test report for every relay, on standard forms with numerical results
- Final as-left setting file and a backup copy
- Test files and recorded reports (ready for the client and consultant)
- Commissioning checklist and final acceptance sheet
References: IEC 60255 (measuring relays and protection equipment), IEC 61850 (substation communication), IEC 61869 (instrument transformers).
Scope of work
- Three-phase secondary injection (Omicron, Megger, Doble)
- Full setting verification and setting-group loading
- Logic, interlock, auto-reclose and trip-chain testing down to the breaker
- Distance, differential and directional characteristic testing
- Signal tests to SCADA and GOOSE (IEC 61850)
- LV, MV and HV relays from Siemens, Schneider, GE, ABB and SEL
- Official test report and as-left setting file