Single-Pole Tripping Applications - GE L60 Instruction Manual

9.2 DISTANCE BACKUP/SUPERVISION 9 APPLICATION OF SETTINGS
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.

9.2.8 SINGLE-POLE TRIPPING APPLICATIONS

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 1-pole trip, the open pole condition is set ½ cycle later, even if the pole is not yet physi-
cally 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 3-pole trip. To avoid this, simple logic (see example shown) must be imple-
mented and mapped to the Trip 1-Pole Input. The Virtual Output 87PC TRIPOUT (VO45) operates when single-pole trip-
ping occurs and is mapped to the Trip 1-Pole Input. To avoid forcing a 3-pole trip, VO45 is reset shortly after the 1-pole trip
operation.
Figure 9–6: SINGLE-POLE TRIPPING WITH 87PC FLEXLOGIC™ EXAMPLE
To provide tripping for evolving faults during open pole conditions, the 87PC TRIPEVL (VO46) output is provided and
mapped into 3-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 setting plus a 1 to 1.5 cycle secu-
87PC RESET
rity margin). Depending on the load current and FDL/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.
9
Figure 9–7: TRIP OUTPUT WITH 87PC SETUP EXAMPLE
9-8 L60 Line Phase Comparison Relay GE Multilin