10.2 DISTANCE BACKUP/SUPERVISION
The phase comparison process of exchanging with HF signals is ready when the operating current (mixed or zero-
sequence) is above 2%. If an internal fault is detected, the challenge is to provide starting transmitting signals at both ends
and to have enough operating quantity for arming FDH to operate and to allow tripping.
The L60 provides functionality for single-pole tripping from 87PC, distance functions, or instantaneous overcurrent ele-
ments via the trip output element. 87PC can detect internal faults on the line but not faulted phases, since the phase cur-
rents are combined in one quantity. Faulted phases are detected by the phase selector, which signals to the trip output
element the type of fault present to correctly trip.
Once the trip output produces a single-pole trip, the open pole condition is set ½ cycle later, even if the pole is not yet phys-
ically open and 87PC is not reset, as the fault is not interrupted by the breaker. Therefore, mapping the 87PC function
directly to the trip output will always cause a three-pole trip. To avoid this, simple logic (see example shown) must be imple-
mented and mapped to the
occurs and is mapped to the
single-pole trip operation.
To provide tripping for evolving faults during open pole conditions, the
into three-pole trip input of the trip output function. Once the breaker pole opens and the fault is interrupted, 87PC is reset
and ready for the next operation 50 ms later (this time is dictated by the
margin). Depending on the load current, FDL, and FDH settings, the relay can be exchanging with squares. However, this
appears as through current and no 87PC operation occurs. However, if a fault occurs during the open pole condition, then
87PC operates again and requests the trip output element to trip the remaining two phases.
Input. The virtual output
Input. To avoid forcing a three-pole trip, virtual output 45 is reset shortly after the
Figure 10–7: SINGLE-POLE TRIPPING WITH 87PC FLEXLOGIC™ EXAMPLE
Figure 10–8: TRIP OUTPUT WITH 87PC SETUP EXAMPLE
L60 Line Phase Comparison System
10 APPLICATION OF SETTINGS
10.2.8 SINGLE-POLE TRIPPING APPLICATIONS
operates when single-pole tripping
87PC TRIPOUT (VO45)
output is provided and mapped
87PC TRIPEVL (VO46)
setting plus a 1 to 1.5 cycle security