1
PSM
2
Rs
(+)
(-)
HW
S W
PO1
TCS1
IS
V
IS: Constant current generator.
Current level ~ 1,0 mA (I
c
)
V: Transient Voltage Suppressor
Breakdown Voltage 380 to 400 VDC
I
c
CBPOS_open
TCSSCBR
TCS_STATE
BLOCK
ALARM
IEC13000026-2-en.vsd
GUID-6B09F9C7-86D0-4A7A-8E08-8E37CAE53249 V3 EN
Figure 77: Operating principle of the trip-circuit supervision without an external
resistor. The circuit breaker open indication is set to block TCSSCBR
when the circuit breaker is open.
Trip-circuit supervision and other trip contacts
It is typical that the trip circuit contains more than one trip contact in parallel, for
example in transformer feeders where the trip of a Buchholz relay is connected in
parallel with the feeder terminal and other relays involved.
GUID-7264738C-F9D7-48F0-B6FC-F85FD10D5B84 V1 EN
Figure 78: Constant test current flow in parallel trip contacts and trip-circuit
supervision
Section 9 1MRK 505 291-UEN A
Secondary system supervision
180
Application manual
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