ABB REU 610, Техническое справочное руководство

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49
U - R +R +R I 20 V AC/DC
tc ext int s tc
( )
× ≥
(5)
U
tc
= operating voltage over the supervised trip
circuit
I
tc
= current flowing through the trip circuit,
~1.5 mA
R
ext
= external shunt resistor
R
int
= internal shunt resistor, 1 k
Ω
R
s
= trip coil resistance
The external shunt resistor is used to enable trip-circuit supervision also when
the circuit breaker is open.
The resistance of the external shunt resistor is to be calculated so that it does
not cause malfunction of the trip-circuit supervision or affect the operation of
the trip coil. Too high resistance causes too high voltage drop, which in turn
results in the operation conditions not being fulfilled, whereas too low
resistance may cause faulty operation of the trip coil.
The following values are recommended for the external resistor, R
ext
:
Table 5.1.5.-1 Recommended values for R
ext
Operating voltage, U
tc
Shunt resistor R
ext
48 V DC 1.2 k
Ω
, 5 W
60 V DC 5.6 k
Ω
, 5 W
110 V DC 22 k
Ω
, 5 W
220 V DC 33 k
Ω
, 5 W
The circuit breaker is to be provided with two external contacts, one opening
and one closing contact. The closing contact is to be connected in parallel
with the external shunt resistor, which enables trip-circuit supervision when
the circuit breaker is closed. The opening contact, on the contrary, is to be
connected in series with the external shunt resistor, which enables trip-circuit
supervision when the circuit breaker is open; see Fig. 5.1.5.-1.
Trip-circuit supervision can be selected either via the HMI or with SPA
parameter
V113
.
1MRS755972
Voltage Relay
Technical Reference Manual - ANSI Version
REU 610