INDUSTRIAL RELAYS and THEIR NUMBERS:
1) REF601 – This type of relay is most commonly used in dedicated
feeder protection. Used in dedicated three-stage overcurrent
protection, two-stage earth-fault protection, non -directional over-
current, non-directional earth fault protections.
2) RET615 - This type of relay is used as transformer protection. Used in
differential voltage protection, higher numerically low-impedance
restricted earth fault.
3) 50P – instantaneous overcurrent relay. Used mainly as negative
sequence relaying operation.
4) 27 – undervoltage relay. used in undervoltage protection
5) 51N, 50G,51G,67N,67G- directional and non-directional earth fault
protection.
6) Feeder earth-fault protection:
– Admittance-based earth-fault protection (67NYH)
– Multifrequency admittance-based earth-fault protection (67NYH)
– Touch voltage-based earth-fault protection (46SNQ, 59N)
– Wattmetric-based earth-fault protection (32N)
– Transient/intermittent earth-fault protection (67NTEF, 67NIEF)
– Harmonics-based earth-fault protection (51NH)
– Neutral power directional element (67N-TC)
7) Line-distance protection:
– Five-zone full scheme distance protection (21P, 21N)
– Power swing blocking (68) – Scheme communication logic (85 21SCHLGC)
– Weak infeed and current reversal logic (85 21CREV, WEI)
– Local acceleration logic (21LAL)
– Scheme communication logic for residual overcurrent (85 67G/ N SCHLGC)
– Weak infeed and current reversal logic for residual overcurrent (85 67G/N CREV, WEI)
The relay includes a dedicated optical protection communication channel for distances
up to 50 kilometers that allows transferring up to 16 binary signals between the line
ends.
8) Line-distance protection:
– Phase-segregated line differential protection (87L)
• Biased low-set stage and unbiased high-set stage
• Support for applications with an in-zone transformer
– Protection communication via an inbuilt dedicated optical link
• Maximum distance with optical link: 50 km
The protection communication channel allows transferring up to 16 binary signals
between the line ends (BST).
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9)Machine protection:
– Thermal overload protection (49M)
– Rotor thermal overload protection (49R)
– Reverse power/directional overpower protection (32R/32O)
– Low-impedance differential protection (87M, 87G)
– High-impedance differential protection (87)
– Flux-balance differential protection (87HIM)
– Negative-sequence overcurrent protection (46M)
– Loss of load protection (37)
– Load jam protection (50TDJAM)
– Start-up supervision (49, 66, 48, 50TDLR)
– Phase reversal protection (46R)
– Emergency start-up (EST, 62)
– Start-up counter (66)
10)Busbar protection:
– High-impedance differential protection (87)
11)Peterson coil protection:
– Petersen coil controller (90)
• Control based on the healthy-state residual voltage
• Control enhanced by the measured coil current
• User-defined parameters for connecting and disconnecting the coil’s parallel resistance
• Control for an additional fixed-type parallel coil
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