Set the IDLDPU with a sufficient margin below the minimum expected load current. A
safety margin of at least 15-20% is recommended. The operate value must however
exceed the maximum charging current of an overhead line, when only one phase is
disconnected (mutual coupling to the other phases).
Set the VDLDPU with a sufficient margin below the minimum expected operating
voltage. A safety margin of at least 15% is recommended.
9.3 Breaker close/trip circuit monitoring TCSSCBR
9.3.1 Identification
Function description IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Breaker close/trip circuit monitoring TCSSCBR - -
9.3.2 Application
TCSSCBR detects faults in the electrical control circuit of the circuit breaker. The
function can supervise both open and closed coil circuits. This kind of monitoring is
necessary to find out the vitality of the control circuits continuously.
Trip circuit supervision generates a current of approximately 1.0 mA
through the supervised circuit. It must be ensured that this current will not
cause a latch up of the controlled object.
To protect the trip circuit supervision circuits in the IED, the output
contacts are provided with parallel transient voltage suppressors. The
breakdown voltage of these suppressors is 400 +/– 20 V DC.
The following figure shows an application of the trip-circuit monitoring function usage.
The best solution is to connect an external R
ext
shunt resistor in parallel with the circuit
breaker internal contact. Although the circuit breaker internal contact is open, TCSSCBR
can see the trip circuit through R
ext
. The R
ext
resistor should have such a resistance that the
current through the resistance remains small, that is, it does not harm or overload the
circuit breaker's trip coil.
1MRK 511 286-UUS A Section 9
Secondary system supervision
177
Application manual
To Next Page
Loading...
