Tripping Logic Smpptrc (94) - ABB RELION 670 Series Applications Manual

1MRK 511 364-UUS A
Section 15
15.1

Tripping logic SMPPTRC (94)

15.1.1 Application
All trip signals from the different protection functions shall be routed through the trip logic. In its
simplest alternative the logic will only link the TRIP signal and make sure that it is long enough.
Tripping logic SMPPTRC (94) offers three different operating modes:
• Three-pole tripping for all fault types (3ph operating mode)
• Single-pole tripping for single-phase faults and three-pole tripping for multi-phase and
evolving faults (1ph/3ph operating mode). The logic also issues a three-pole tripping
command when phase selection within the operating protection functions is not possible, or
when external conditions request three-pole tripping.
• Two-pole tripping for two-phase faults.
The three-pole trip for all faults offers a simple solution and is often sufficient in well meshed
transmission systems and in sub-transmission systems. Since most faults, especially at the
highest voltage levels, are single phase-to-ground faults, single-pole tripping can be of great
value. If only the faulty phase is tripped, power can still be transferred on the line during the dead
time that arises before reclosing. Single-pole tripping during single-phase faults must be
combined with single pole reclosing.
To meet the different double, breaker-and-a-half and other multiple circuit breaker arrangements,
two identical SMPPTRC (94) function blocks may be provided within the IED.
One SMPPTRC (94) function block should be used for each breaker, if the line is connected to the
substation via more than one breaker. Assume that single-pole tripping and autoreclosing is used
on the line. Both breakers are then normally set up for 1/3-pole tripping and 1/3-phase
autoreclosing. As an alternative, the breaker chosen as master can have single-pole tripping, while
the slave breaker could have three-pole tripping and autoreclosing. In the case of a permanent
fault, only one of the breakers has to be operated when the fault is energized a second time. In the
event of a transient fault the slave breaker performs a three-pole reclosing onto the non-faulted
line.
The same philosophy can be used for two-pole tripping and autoreclosing.
To prevent closing of a circuit breaker after a trip the function can block the closing.
The two instances of the SMPPTRC (94) function are identical except, for the name of the function
block (SMPPTRC1 and SMPPTRC2). References will therefore only be made to SMPPTRC1 in the
following description, but they also apply to SMPPTRC2.
Application manual
Logic
Section 15
Logic
IP14576-1 v4
M12252-3 v8
199