ABB Relion 670 Series Applications Manual page 180

Section 7
Current protection
RetripMode : This setting states how the re-trip function shall operate. Retrip Off means that the
re-trip function is not activated.
that a phase current must be larger than the operate level to allow re-trip.
breaker position check) and
position is used).
Pickup_PH : Current level for detection of breaker failure, set in % of IBase . This parameter must be
set so that faults with small fault current can be detected. The setting can be chosen in
accordance with the most sensitive protection function to initiate the breaker failure protection.
Typical setting is 10% of
PU_BlkCont : If any contact based detection of breaker failure is used this function can be blocked
if the current is larger than this setting level. If the
breaker failure for high current faults are safely detected by the current measurement function. To
increase security the contact based function must be disabled for high currents. The setting can
be given within the range 5 – 200% of
t1 : Time delay of the re-trip. The setting can be given within the range 0 – 60 s in steps of 0.001 s.
Typical setting is 0 – 50 ms.
t2 : Time delay of the back-up trip. The choice of this setting is made as short as possible at the
same time as unwanted operation must be avoided. Typical setting is 90 – 150 ms (also dependent
of re-trip timer).
The minimum time delay for the re-trip can be estimated as:
³ +
t 2 t 1
EQUATION1430 V1 EN-US
where:
t
cbopen
t
BFP_reset
t
margin
It is often required that the total fault clearance time shall be less than a given critical time. This
time is often dependent of the ability to maintain transient stability in case of a fault close to a
power plant.
174
CB Pos Check (circuit breaker position check) and Current means
Contact means retrip is done when circuit breaker is closed (breaker
No CB Pos Check means re-trip is done without check of breaker position.
IBase .
+ +
t t t
cbopen BFP reset _ margin
is the maximum opening time for the circuit breaker
is the maximum time for breaker failure protection to detect correct breaker function
(the current criteria reset)
is a safety margin
FunctionMode is set to Current&Contact
IBase .
1MRK 511 358-UUS A
CB Pos Check (circuit
(Equation 63)
Application manual