Optional functions are available in the relay default content when a corresponding option is selected while ordering the relay. However, the functions are not preengineered to be part of the default configuration. The functions can be engineered into use.
Interconnection protection functions include the directional reactive power undervoltage protection DQPTUV1 and the three instances of low-voltage ride-through protection LVRTPTUV1…3. These functions can be used in the common point of coupling of utility grid and distributed energy resource, depending on the selected setting to disconnect the distributed power generation to support utility grid stability and to detect islanding. They can also be used to disconnect the distributed generator from common point of coupling. A failure in the voltage measuring circuit detected by the fuse failure function can be used to block LVRTPTUV1…3 and DQPTUV1 protection. These interconnection functions can be engineered to work together with basic functions in relay default configuration to cover different needs placed for relay operation in different grid codes.
Two instances of directional underpower protection DUPPDPR1 and DUPPDPR2 are provided. Normally these are used in supervision of underpower or underloading situations.
Three instances of directional overpower protection DOPPDPR1, DOPPDPR2 and DOPPDPR3 are provided to supervision of overpower or overloading situations with power flow direction information.
On losing excitation, a motor may overspeed and operate as an induction motor taking reactive power from the system which may reduce system voltages. Three-phase underexcitation protection UEXPDIS is provided to detect such conditions. Directional underpower protection is disabled when the motor circuit breaker is in open position.