VAMP 52 - Page 189

Technical description 7 Application 7.3 Trip circuit supervision
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Figure 7.3.1-3 An example of digital input DI1 configuration for trip circuit
supervision with one digital input.
Figure 7.3.1-4 An example of output matrix configuration for trip circuit
supervision with one digital input.
Example of dimensioning the external resistor R:
U
aux
= 110 Vdc –20 % + 10%
Auxiliary voltage with tolerance
U
DI
= 18 Vdc
Threshold voltage of the digital input
I
DI
= 3 mA
Typical current needed to activate the digital input
including a 1 mA safety margin.
P
coil
= 50 W
Rated power of the open coil of the circuit breaker. If
this value is not known, 0  can be used for the R
coil
.
U
min
= U
aux
– 20 % = 88 V
U
max
= U
aux
+ 10 % = 121 V
R
coil
=
U
2
aux
/P = 242 .