U-R Voltage across the substitute resistor
R Bypass resistor
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:
[mi-ausloesekreis-widerstand1-021026-rei, 1, en_GB]
In order that the minimum voltage for controlling the binary input is ensured, R
max
is derived as:
[mi-ausloesekreis-widerstand2-021026-rei, 1, en_GB]
So the circuit breaker trip coil does not remain energized in the above case, R
min
is derived as:
[mi-ausloesekreis-widerstand3-021026-rei, 1, en_GB]
Ι
BI (HIGH)
Constant Current with BI on (= 1.7 mA)
U
BI min
Minimum control voltage for BI (= 19 V for delivery setting for nominal
voltage of 24 V/48 V/60 V; 88 V for delivery setting for nominal voltage
of 110 V/125 V/220 V/250 V)
U
CTR
Control voltage for trip circuit
R
TC
DC resistance of circuit breaker trip coil
U
TC (LOW)
maximum voltage on the circuit breaker trip coil that does not lead to
tripping
If the calculation results in R
max
< R
min
, then the calculation must be repeated with the next lower switching
threshold U
BI min
, and this threshold must be implemented in the relay using plug-in jumpers.
For the power consumption of the resistor the following applies:
[mi-ausloesekreis-leistung-021026-rei, 1, en_GB]
Example
Ι
BI (HIGH)
1.7 mA (SIPROTEC 4 device 7UT6x)
U
BI min
19 V for delivery setting for nominal voltages of 24 V/48 V/60 V
(SIPROTEC 4 device 7UT6x)
88 V for delivery setting for nominal voltages of 110 V/125 V/220 V/
250 V (SIPROTEC 4 device 7UT6x)
U
CTR
110 V (from system / trip circuit)
R
TC
500 Ω (from system / trip circuit)
U
TC (LOW)
2 V (from system / trip circuit)
[mi-ausloesekreis-beispwiderstand1-021026-rei, 1, en_GB]
Mounting and Commissioning
3.1 Mounting and Connections
SIPROTEC 4, 7UT6x, Manual 313
C53000-G1176-C230-5, Edition 09.2016
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