Installation and Commissioning
8-12 7SA6 Manual
C53000-G1176-C156-2
This resultsin an upper limit for the resistancedimension, R
max
,andalowerlimitR
min
,
from which the optimal value of the arithmetic mean should be selected.
To ensure the minimum voltage for the control of the binary input, R
max
is derived as:
So the circuit breaker trip coil does not remain energized in the above case, R
min
is
derived as:
If the calculation results that R
max
<R
min
, then the calculation must be repeated, with
the next lowest switching threshold U
BI min
, and this threshold must be implemented
in the relay using plug-in bridges (see Sub-section 8.1.3).
For the power consumption of the resistance:
Example:
I
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 24/48/60 V;
=73 V for delivery setting for nominal voltage of 110/125/220/250 V;
UCTR
Control voltage for trip circuit
R
CBTC
DC resistance of circuit breaker trip coil
U
CBTC (LOW)
Maximum voltage on the circuit breaker trip coil that does not lead to tripping
I
BI (HIGH)
1.8 mA (from SIPROTEC
®
7SA6)
U
BI min
19 V for delivery setting for nominal voltage 24/48/60 V
73 V or delivery setting for nominal voltage 110/125/220/250 V
UCTR 110 V (from system / release circuit)
R
CBTC
500 Ω (from system / release circuit)
U
CBTC (LOW)
2 V (from system / release circuit)
R
R
max
R
min
+
2
---------------------------------=
R
max
U
CRT
U
BI min
–
I
BI (High)
--------------------------------------
èø
æö
R
CBTC
–=
R
min
R
TC
U
CTR
U
TC (LOW)
–
U
TC (LOW)
-----------------------------------------------
èø
æö
⋅
=
P
R
I
2
R⋅
U
CTR
RR
CBTC
+
----------------------------
èø
æö
2
R⋅==
R
max
110V-19V
1.8 m
Α
---------------------------------
èø
æö
500Ω–=
R
min
500Ω
110 V - 2 V
2V
------------------------------
èø
æö
⋅=
R
max
50.1 kΩ=
R
min
27 kΩ=
R
R
max
R
min
+
2
--------------------------------
38.6 k
Ω==
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