Motor Protection

  • Trainer: Dr. Saeed Roostaee (Profile)
  • Online
  • Date: 19 and 20 August 2023
  • Platform: Google Meet & Online player
  • Last update: 6 August 2023
  • Contact us

Course content:

  • Basics of Synchronous and Asynchronous Motors
  • Motor Nameplate
  • Motor Connections
  • Motor Faults, Faults, and Protection Functions
  • Overview of the Motor Protection Functions
  • Motor Overcurrent Protection
  • Motor Earth fault protection
  • Motor Overload protection
  • Motor Voltage protection
  • Negative Sequence Protection
  • Motor Lock Rotor & Mechanical Jam protection
  • Motor Undercurrent protection


Three-phase induction motors are the most common and frequently encountered machines in the industry

Modern numerical motor relay protection technology must be sufficient to meet the protection requirements of any of the vast range of motor designs. A motor protection relay providing sufficient protection will have the following set of characteristics such as extended start relay protection, loss-of-load relay protection, number of starts limitation, stalling relay protection, short circuit relay protection, thermal relay protection, Earth fault relay protection, negative sequence current detection, winding RTD measurement/trip, under-voltage relay protection, auxiliary supply supervision, …

  • 14 Speed Switch
  • 27 Undervoltage*
  • 37 (P,C) Underpower/Undercurrent
  • 38 Bearing Temperature*
  • 46 Current Unbalance
  • 47 Phase Reversal
  • 49P PTC Overtemperature*
  • 49R RTD Thermal*
  • 49T Thermal Model
  • 50 (P,G,Q) Overcurrent (Phase, Ground, Neg. Seq.)
  • 50P LR Locked Rotor
  • 50P LJ Load Jam
  • 50N Neutral Overcurrent
  • 51 (P,G,Q) Time-Overcurrent (Phase, Residual, Neg. Seq.)
  • 55 Power Factor*
  • 59P Phase Overvoltage*
  • 60 Loss-of-Potential*
  • 66 Starts-Per-Hour
  • 81 (O,U) Over-/Underfrequency
  • 87 Current Differential*
  • 90 (P,I,T) Load Control (Power, Current, Thermal Capacity)
  • 50/51 Adaptive Overcurrent
  • 85 RIO SEL Mirrored Bits® Communications
  • DFR Event Reports—Motor Starts, Motor Operating
  • Statistics
  • ENV Optional SEL-2600 RTD Module*
  • HMI Operator Interface
  • LDP Load Data Profiling
  • LGC SELogic® Control Equations
  • MET Metering
  • RTU Remote Terminal Unit
  • SDTM Slip-Dependent AccuTrackTM Thermal Model
  • SER Sequential Events Recorders
SEL710 Motor Protection Relay
  • Stator overload protection 49
  • Starting time supervision, locked rotor protection 48
  • Restart inhibit 66,49R
  • Negative-sequence current protection I2> 46
  • Thermal unbalanced-load protection I2 2(t) 46
  • Temperature measurement 1 38
  • Undercurrent protection 37
  • Active-power protection (P<) 32U
  • Sensitive ground-fault protection 59N,
  • non-directional 51Ns
  • directional 67Ns
  • Overcurrent protection 50, 51
  • Current-differential protection 87
  • Undervoltage protection 27
  • Overvoltage protection 59
  • Underexcitation protection 40
  • Rotor ground-fault protection 64R
  • Frequency protection 81
  • Circuit-breaker failure protection 50BF
  • User-programmable logic (CFC)
  • Control functionality
  • Graphic display (large)
  • Flexible interfaces
  • Frequency operating range (10 Hz – 70 Hz)
  • Operational measured values and
  • functional measured values
SIPROTEC 5 Motor Protection relays

ABB REM543 and ABB REM545 Motor protection IEDs
  • Three-phase non-directional overcurrent protection, low-stage PHLPTOC 3I> 51P-1
  • Three-phase non-directional overcurrent protection, instantaneous stage PHIPTOC 3I>>> 50P/51P
  • Non-directional earth-fault protection, low-stage EFLPTOC I0> 51N-1
  • Non-directional earth-fault protection, high stage EFHPTOC I0>> 51N-2
  • Non-directional earth-fault protection, instantaneous stage EFIPTOC I0>>> 50N/51N
  • Directional earth-fault protection, low stage DEFLPDEF I0> -> 67N-1
  • Directional earth-fault protection, high stage DEFHPDEF I0>> -> 67N-2
  • Rotor earth-fault protection MREFPTOC Io>R 64R
  • Negative-sequence overcurrent protection for machines MNSPTOC I2>G/M 46G/46M
  • Phase-reversal protection PREVPTOC I2>> 46R
  • Three-phase thermal overload protection for motors MPTTR 3Ith>M 49M
  • Motor startup supervision STTPMSU Is2t n< 48,66,14,51LR Motor load jam protection JAMPTOC Ist> 51LR
  • Emergency start ESMGAPC ESTART ESTART
  • Loss of load supervision LOFLPTUC 3I< 37 High-impedance or flux-balance based differential protection for machines MHZPDIF 3dIHi>G/M 87GH/87MH
  • Stabilized differential protection for machines MPDIF 3dI>G/M 87G/87M
  • Three-phase overvoltage protection PHPTOV 3U> 59
  • Three-phase undervoltage protection PHPTUV 3U< 27 Positive-sequence overvoltage protection PSPTOV U1> 47O+
  • Positive-sequence Undervoltage protection PSPTUV U1< 47U+ Negative-sequence overvoltage protection NSPTOV U2> 47OResidual
  • overvoltage protection ROVPTOV U0> 59G
  • Reverse power/directional overpower protection DOPPDPR P> 32R/32O
  • Frequency gradient protection DAPFRC df/dt> 81R
  • Over frequency protection DAPTOF f> 81O
  • Under frequency protection DAPTUF f< 81U Three-phase underexcitation protection UEXPDIS X< 40 Circuit breaker failure protection CCBRBRF 3I>/I0>BF 51BF/51NBF
  • Tripping logic TRPPTRC I -> O 94
  • Multipurpose analog protection MAPGAPC MAP MAP
  • Bay control QCCBAY CBAY CBAY
  • Interlocking interface SCILO 3 3
  • Circuit breaker/disconnector control GNRLCSWI I <-> O CB/DC I <-> O CB/DC
  • Circuit breaker DAXCBR I <-> O CB I <-> O CB
  • Disconnector DAXSWI I <-> O DC I <-> O DC
  • Local/remote switch interface LOCREM R/L R/L
  • Single point control (8 signals) SPC8GGIO
  • Double point indication DPGGIO
  • Single point indication SPGGIO
  • Generic measured value MVGGIO
  • Logic Rotating Switch for function selection and LHMI presentation SLGGIO
  • Selector mini switch VSGGIO
  • Pulse counter for energy metering PCGGIO
  • Event counter CNTGGIO
  • Supervision and monitoring
  • Runtime counter for machines and devices MDSOPT OPTS OPTM
  • Circuit breaker condition monitoring SSCBR CBCM CBCM
  • Fuse failure supervision SEQRFUF FUSEF 60
  • Current circuit supervision CCRDIF MCS 3I MCS 3I
  • Trip-circuit supervision TCSSCBR TCS TCM
  • Station battery supervision SPVNZBAT U<> U<>
  • Energy monitoring EPDMMTR E E
  • Measured value limit supervision MVEXP
  • Three-phase current measurement CMMXU 3I 3I
  • Three-phase voltage measurement (phase-to-earth)
  • VPHMMXU 3Upe 3Upe
  • Three-phase voltage measurement (phase-to-phase) VPPMMXU 3Upp 3Upp
  • Residual current measurement RESCMMXU I0 I0
  • Residual voltage measurement RESVMMXU U0 U0
  • Power monitoring with P, Q, S, power factor, frequency PWRMMXU PQf PQf
  • Sequence current measurement CSMSQI I1, I2 I1, I2
  • Sequence voltage measurement VSMSQI U1, U2 V1, V2
REM 543 Motor protection relay
GE motor protection relays – SR469, GE 369, GE869
  • Current Protection: Phase Overcurrent (67, 51, 50)
  • Directional Control of Overcurrent Protection (67)
  • Overcurrent Protection (50)
  • Current Protection: Undercurrent (37)
  • Phase Unbalance (46)
  • Time Delayed Overcurrent Protection (51)
  • Current Protection: Measured Earth Fault (50/51G)
  • Directional Control of Measured Earth Fault Protection (67G)
  • Measured Earth Fault Protection (50G)
  • Time Delayed Measured Earth Fault Protection (51G)
  • Current Protection: Derived Earth Fault (50/51N)
  • Directional Control of Derived Earth Fault Protection (67N)
  • Time Delayed Derived Earth Fault Protection (51N)
  • High Impedance Restricted Earth Fault (87REF)
  • Voltage Protection: NPS Overvoltage (47)
  • Earth Fault Protection (50N)
  • Voltage Protection: Under/Over Frequency (81)
  • Power Protection – 32
  • Sensitive Power Protection – 32S
  • Break Capacity Limit (50BCL)
  • Phase Reversal (46 PH REV)
  • Temperature Monitoring
  • CT Supervision (60CTS)
  • Power Factor – 55
  • Trip Circuit Supervision (74TCS)
  • Close Circuit Supervision (74CCS)
  • Circuit Breaker Failure (50BF)
7SR17 Rho Motor Protection Relay

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