Mounting and Commissioning
3.1 Mounting and Connections
SIPROTEC, 7SD80, Manual
E50417-G1140-C474-A1, Release date 09.2011
235
This results in an upper limit for the resistance dimension, R
max
, and a lower limit R
min
, from which the optimal
value of the arithmetic mean R should be selected:
In order that the minimum voltage for controlling the binary input is ensured, R
max
is derived as:
To keep the circuit breaker trip coil energized in the above case, R
min
is derived as:
If the calculation has the result R
max
< R
min
, the calculation has to be repeated with the next smaller threshold
V
BI min
. This threshold is determined via the parameters 260 Threshold BI 1 to 266 Threshold BI 7 The
settings Thresh. BI 176V, Thresh. BI 88V, Thresh. BI 19V are possible.
For the power consumption of the resistance:
I
BI (HIGH)
Constant current with activated BI ( = 0.25 mA)
V
BI min
Minimum control voltage for BI (= 19 V at delivery setting for nominal voltages of 24
V/ 48 V; 88 V at delivery setting for nominal voltages of 60 V/ 110 V/ 125 V/ 220 V/
250 V)
V
CTR
Control voltage for trip circuit
R
CBTC
Ohmic resistance of the circuit breaker coil
V
CBTC (LOW)
Maximum voltage on the circuit breaker coil that does not lead to tripping
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