Control Protection Relays

Name	Description
21 - MHO Distance Relay	This block models a generic MHO phase distance element with 2 protection zones.
25 - Synchronism-Check Relay	This block models a generic 25 synchronism-check or sync-check relay.
27 - Undervoltage Relay	The under-voltage relay (27) operates when the voltage it monitors falls below a set of threshold values.
27 - Undervoltage Relay (1-ph)	This component is a single phase under-voltage (27) relay with voltage magnitude as the input.
40Q - Loss-of-Excitation Relay	The Var-type loss-of-excitation relay (40Q) operates when the reactive power that a synchronous generator consumes from the system exceeds the threshold.
49M - Thermal Overload Protection for Motors	This block models a 49M - Thermal overload protection function for motors.
50-51 - Overcurrent Relay	This relay comprises functionalities of the 50P (instantaneous or definite-time), 51P (inverse-time) and 51G (inverse-time) elements.
50 - Instantaneous or Definite Time Overcurrent Relay (1-ph)	This component is a instantaneous or definite time overcurrent (50P) relay with current magnitude as the input.
50BF - Breaker Failure Protection	This relay detects a breaker failure to operate during fault and thus issues a back-up trip command to adjacent circuit breakers.
51 - Inverse Time Overcurrent (1-ph)	This component is a single phase inverse time overcurrent (51P) relay with current magnitude as the input.
59 - Overvoltage Relay	The over-voltage relay (59) operates when the voltage it monitors exceeds a set of threshold values.
59 - Overvoltage Relay (1-ph)	This component is a single phase overvoltage (59) relay with voltage magnitude as the input.
67 - Directional Overcurrent Relay	The directional overcurrent relay (50-51-67) trips if and only if the fault current magnitude is above the threshold (50-51) and it is in a specific direction (67).
67 - Directional Relay Based on Impedance	The 67 directional relay can detect the direction of the input current using impedance and torque which are calculated for their respective elements.
79 - Auto recloser	This relay issues a close breaker command in a power system to restore services after a transient line fault.
81 - Frequency Relay	This frequency relay (81) includes three types of frequency elements, namely the overfrequency (81O), the under-frequency (81U) and the rate-of-change-of-frequency (ROCOF) (81R) elements.
87T - Transformer Differential Relay	This model implements a transformer differential relay (87T) with harmonic restraint and harmonic blocking functions.