Trip Circuit Supervision - Siemens siprotec 7SA6 User Manual

6.19.1.4 Trip Circuit Supervision

Supervision Using
Two Binary Inputs
7SA6 Manual
C53000-G1176-C133-1
during the voltage failure if the overcurrent protection was configured accordingly
(refer to Section 6.9).
The distance protection 7SA6 incorporates an integrated trip circuit supervision
function. Depending on the number of binary inputs with isolated control inputs that
are still available, a choice can be made between monitoring with one or with two
binary inputs. If the allocation of the required binary inputs does not match the selected
monitoring mode, a corresponding alarm is issued ("7ULS& 3URJ)$,/" along with
the number of the faulty monitoring circuit). If two binary inputs are used, disturbances
of the trip circuit can be detected during all switching states. With only one binary input,
faults in the circuit breaker can not be detected. If single-pole tripping is possible, a
separate trip circuit supervision can be implemented for each circuit breaker pole
provided the required binary inputs are available.
If two binary inputs are used, these are connected as shown in Figure 6-134. The one
binary input is connected in parallel to the corresponding trip relay contact of the
protection while the other is connected in parallel to the circuit breaker auxiliary
contacts.
A prerequisite for use of the trip circuit supervision function is that the control voltage
of the circuit breaker is greater than the sum of the minimum voltage drops across the
two binary inputs (U > 2·U
C
monitoring can only be used if the trip control voltage is greater than 38 V.
L
+
TR
Aux1
TC
CB
L
–
Figure 6-134 Trip circuit supervision operating principle with two binary inputs
The monitoring with two binary inputs not only detects interruptions of the trip circuit
and failure of the control voltage, but also monitors the reaction of the circuit breaker
by means of the switching state of the circuit breaker auxiliary contacts.
Depending on the switching state of the trip relay and circuit breaker, the binary inputs
are initiated (logic state "H" in Table 6-11) or short circuited (logic state "L").
). As at least 19 V is necessary per binary input, the
BImin
U
C
U
BI1
7SA6
U
BI2
Aux2
7SA6
>Trip C1 TripRel
>Trip C1 Bkr.Rel
Legend:
TR — trip relay contact
CB — circuit breaker
TC — circuit breaker trip coil
Aux1 — circuit breaker auxiliary contact
(normally open)
Aux2 — circuit breaker auxiliary contact
(normally closed)
U — control voltage (tripping voltage)
C
U — input voltage of the 1st binary input
BI1
U — input voltage of the 2nd binary input
BI2
Note: The circuit breaker is shown in closed position!
Functions
6-259