Sepam M Series
Sepam M Series Motor Protection Relay

When MV motor protection is needed — including thermal overload, locked rotor, starts per hour, negative sequence and RTD temperature monitoring — the Sepam M Series is what we specify. Model M20 covers essential motor protection for straightforward applications while M41 and M87 add directional functions and differential protection for larger or more critical motors.
About this product
The Schneider Electric Sepam M Series provides dedicated MV motor protection for the full range of medium voltage motor applications from straightforward induction motors to large critical process motors requiring differential protection. The series covers all essential motor protection functions including thermal overload (49RMS), overcurrent (50/51), earth fault (50N/51N), locked rotor detection (48), starts per hour limitation (66), negative sequence (46), undercurrent (37) and under/overvoltage and frequency, plus directional earth fault (67N) on M41 and above for motors in isolated or compensated neutral networks. Model M20 covers the essential protection set with 8 RTD temperature inputs for stator and bearing monitoring, suitable for the majority of standard MV motor applications. M41 extends the protection to include directional earth fault, voltage and frequency protection and 16 RTD inputs for more complex or critical process applications. M87 adds machine differential protection (87M) for large MV motors where internal winding fault detection at the earliest stage is required — typically motors above 1MW in critical process applications. Typical applications include MV motors in pumping stations, compressor drives, mill drives, fans and process drives across water utilities, oil and gas, mining, petrochemical and heavy industry. The selection between M20, M41 and M87 is made based on motor size, network earthing configuration and criticality of the application — with M87 reserved for the most critical large motors where differential protection provides a level of protection beyond what overcurrent-based relays can achieve.
Technical Specifications
| models | M20 / M41 / M87 |
| rtd inputs | up to 16 |
| application | MV motor protection |
| communication | RS485 (IEC 60870-5-103 or Modbus RTU) |
| ansi functions | 50/51/50N/51N/46/49RMS/48/51LR/66/37/27/59/81/50BF/87M (model dependent) |
| machine differential | M87 |
Ordering Options
| Article Code | Description | Notes |
|---|---|---|
| M20 | Essential motor protection: overcurrent + thermal overload + 8 RTD inputs | |
| M41 | M20 + directional earth fault + voltage/frequency + 16 RTD inputs | |
| M87 | Machine differential protection for large MV motors |
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