ABB REX 521 Technical Reference Manual, General

1MRS 751108-MUM
REX 521
27
Protection Relay
Technical Reference Manual, General
Should the external shunt resistance be used, it has to be calculated not to interfere
with the functionality of the supervision or the trip coil. Too high a resistance will
cause too high a voltage drop, jeopardizing the requirement of at least 20 V over the
internal circuit, while a resistance too low may enable false operations of the trip
coil.
Following values are recommended for the external resistor R
ext
:
tcsclose_a
Fig. 4.1.10.-1 Operating principle of the trip-circuit supervision, without an
external resistor. The TCS blocking switch is set, blocking the TCS1
when the circuit breaker is open.
Table 4.1.10-1 Values recommended for R
ext
Operating voltage U
c
Shunt resistor R
ext
48 V DC
1.2 kΩ
, 5 W
60 V DC
5.6 kΩ
, 5 W
110 V DC
22 kΩ, 5 W
220 V DC
33 kΩ, 5 W
+
-
Rs
TCS1
BS
TCSSTATE
ALARM
HW
SW
TCS l a
TCS
R
int
1
2
3
4
X4.2
CBPOS_open
Blocage TCS

ABB REX 521 Specifications

General

Brand	ABB
Model	REX 521
Category	Other
Language	English