Table 22: Values recommended for the external resistor R
ext
Operating voltage U
c
Shunt resistor R
ext
48 V DC 10 kΩ, 5 W
60 V DC 22 kΩ, 5 W
110 V DC 33 kΩ, 5 W
220 V DC 68 kΩ, 5 W
Due to the requirement that the voltage over the TCSSCBR contact must be 20V or
higher, the correct operation is not guaranteed with auxiliary operating voltages lower
than 48V DC because of the voltage drop in R
ext
and the operating coil or even voltage
drop of the feeding auxiliary voltage system which can cause too low voltage values
over the TCSSCBR contact. In this case, erroneous alarming can occur.
At lower (<48V DC) auxiliary circuit operating voltages, it is recommended to use the
circuit breaker position to block unintentional operation of TCSSCBR. The use of the
position indication is described earlier in this chapter.
Section 9 1MRK 505 291-UEN A
Secondary system supervision
182
Application manual
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