A distance protection relay presented in an educational format. Supplied with TecQuipment’s Protection and Relay Test Set (PSL50), the relay enables investigations into the protection and monitoring of overhead transmission lines. The relay is housed in a robust enclosure with carrying handle. The module mounts on the desk area of the Protection and Relay Test Set and connects to it using a multi-core cable and safety leads. 

This relay is also an optional ancillary for selected products in TecQuipment’s Power Systems range. 

The relay module is based on the Micom P441 industrial relay. The lecturer or student sets up different fault circuits on the Protection and Relay Test Set. They then use the keypad and display on the relay module to program it to the settings needed for the tests. They can also use the Micom S1 software (supplied with the Protection and Relay Test Set) and a suitable computer to program the relay module. 

The relay module is then connected to the fault circuits so tests can be performed. Most tests are performed using single relays. However, there are enough connections on the Protection and Relay Test Set to test two relay modules at the same time. The main functions of the Distance Protection Relay include: 

• Full scheme phase and ground distance protection – up to five zones (ANSI 21G and ANSI 21P)
• Directional/non-directional phase overcurrent (ANSI 50, ANSI 51, ANSI 67)
• Directional/non-directional earth fault (ANSI 50N, ANSI 51N, ANSI 67N)
• Directional/non-directional negative sequence overcurrent (ANSI 46, ANSI 67)
• Thermal overload protection (ANSI 49)
• Broken conductor
• Blocking of any one protection element
• Creating fault and disturbance records

Connection to the experimental circuit is via current transformers with ratio to suit the inputs of the relay. This provides an effective demonstration of the effect of current and voltage transformer ratio, connection and rating on protective relays.

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