Microprocessor based relay EPS-D

How does the EPS-D microprocessor-based motor relay work?

The relay monitors the load in each of the three phases. It analyses the motor’s operating condition based on the entered values and the actual current drawn by the motor. By comparing the operating status of the protected motor with the model characteristics stored in the processor’s memory, the EPS-D quickly and with high precision detects any malfunctions, thereby cutting off the motor’s power supply.

Protective functions of the relay

• Thermal protection
• No-load and dry-running protection (undercurrent protection)
• Mechanical overload protection
• Rotor jamming protection
• Frequent start-up protection
• Phase loss protection
• Phase sequence reversal protection
• Load imbalance protection
• Earth fault protection
  
  

Additional functions of the EPS-D microprocessor-based motor relay

• display of motor load values
• message indicating the cause of the protection trip
• motor thermal memory
  
  

How to select a relay for a motor?

The EPS-D motor relay is manufactured in three current ratings: 5 A, 20 A and 100 A. The setting range for the actual operating current for each version is from 0% to 100% of the relay’s rated current (0÷1×In). The selection of the appropriate relay depends on the power of the motor to be protected and its rated current. For motors above 55 kW (>100 A), we use the EPS 5 A and additional external current transformers.

 Please note – new version of the motor relay

Please note that a new version of the motor relay, designated rev. C, is now available. Design changes have been made to the device and its operating procedure has been modified.

To identify the version of the device, check the markings on the first two terminals on the front panel of the relay:

• New version (rev. C) – terminals marked Y1, Y2,

• Previous version – terminals marked C1, C2.

Two versions of the user manual are available in the ‘Downloads’ tab:

• EPS-D – user manual – for the previous version of the device,

• EPS-D – user manual rev. C – for the new version of the device.