The DLPD provides distance protection for HV and EHV transmission lines. It may be used for single or three phase tripping applications. It includes four zones of distance
protection. User selectable pilot schemes are provided with step
distance backup. Ground instantaneous and time overcurrent
functions are independently selectable to be directional or
non-directional. Phase overcurrent backup consists of a non-directional instantaneous function. Undervoltage is provided as well as potential fuse failure detection logic. The DLPD has high speed tripping, typically 0.75 to 1.5 cycles, and out of step blocking.