Schneider Electric P243-311A2MCD28M

comprehensive protection relay Schneider Electric P243-311A2MCD28M

P243-311A2MCD28M is a comprehensive protection relay for rotating machines (motors/generators) from Schneider Electric’s MiCOM P243 series. It is a high-end digital protection device mainly used for the full protection, control and monitoring of large motors and synchronous motors.

1. Model Code Interpretation (P243-311A2MCD28M)

P243: Base series, motor differential protection and integrated management relay.

3: Hardware configuration/version (corresponding to I/O, power supply and interface combination).

11: Protection function configuration (including complete motor protection such as differential, overcurrent, overheating, stall, unbalance protection, etc.).

A2: Auxiliary power supply rating (typically 220–240V AC/DC or 110V DC, subject to nameplate).

M: CT input type (1A / 5A).

C: Communication interface (including Modbus RTU, optional IEC 61850, Profibus DP).

D28: I/O configuration (e.g.: 16 digital inputs / 16 relay outputs).

M: RTD temperature monitoring (supports 6–10 platinum resistance thermometers for winding/bearing temperature measurement).

2. Core Functions & Protection Features
3. Main Protection

87 Motor differential protection (phase-to-phase/turn-to-turn faults)

50/51 Overcurrent/instantaneous overcurrent, 49 Stator overheating, 48 Stall/locked rotor

51N/50N Earth-fault overcurrent, 37 Underpower/overpower, 24 Speed supervision

2. Measurement & Monitoring

Three-phase current, voltage, power, frequency, power factor

RTD temperature monitoring (windings, bearings, cooling medium)

Motor operating hours, start count statistics, event recording (1000+ records)

3. Communication & Control

Standard: Modbus RTU

Optional: IEC 61850, Profibus DP, DNP3.0

Programmable logic (PLC), remote switching, fault recording

3. Typical Applications

High-voltage induction/synchronous motors (water pumps, fans, compressors, rolling mills)

Protection of generators and large rotating machinery

Critical motor circuits in industry, power, metallurgy, petrochemical, municipal engineering, etc.

4. Technical Parameters (Reference)

Operating power supply: 24–240V AC/DC (wide range)

CT input: 1A or 5A

I/O: 16 DI / 16 DO (relay outputs)

RTD: 6–10 channels Pt100/Pt1000

Accuracy: Current ±0.2%, Voltage ±0.5%

Ambient: -25°C ~ +70°C, front panel IP54

5. Differences Within the Same Series

P241: Standard motor protection (without differential)

P242: Enhanced motor protection

P243: Top configuration with differential protection (corresponding to model P243-xxxx)