The TD-4 static timing relay provides a dual time delay function. It is normally applied as a timer for zone 2 and zone 3 phase-distance functions in a stepped distance line relay shceme. Two independent timde delays may be set. The appropriate timing is selected, depending upon which inputs are present.
The first stage being adjustable from 0.1 to 1.0 seconds, and the second stage for 0.5 to 3.0 seconds. The relay operates from a DC source of 48, 125, or 250 volts DC.
This relay is particularly suitable for use as a timing unit for the second and thirdzone KD-4 and KD-41 relays in a compensator distance relaying scheme. By proper connections in the relaying scheme, the TD-4 will provide a single time delay for zone 2 faults, or a longer time delay for zone 3 faults.
- Two-stage timing relay
- Used together with the KD-4 relay for zone 2 and zobe 3 faults