ABB REM 610 Technical Reference Manual page 36

REM 610
36
Motor Protection Relay
Technical Reference Manual
Note!
RTD6 can be used to measure the ambient temperature for the thermal protection
stage. In this case, Ta6> and Tp6> will not be in use. This state will be indicated by
dashes on the LCD and by "-999" when the set alarm/trip value is read via the SPA
bus.
Note!
For as long as the emergency start is activated, Tp1...6> will be increased by 10 per
cent.
Temperature protection using thermistors
REM610 supports PTC thermistors.
When input RTD1/RTD4 is used with thermistors, a trip value, Thp1>/Thp2>, is set
for the respective input.
When the resistance of the thermistor exceeds the set trip value, Thp1>/Thp2>, stage
ThA>/ThB> will generate a trip signal on expiration of the 2 s' fixed operate time.
The trip signal from ThA>/ThB> will be reset in 800 ms after the resistance has
fallen below set trip value Thp1>/Thp2>.
RTD sensor/thermistor connection
When connecting the RTD sensors and the thermistors to the RTD inputs, a
double-shielded cable is to be used. The cable shield is to be connected to the chassis
earth screw on the rear panel of the relay.
The RTD sensors and thermistors are to be connected to the RTD inputs according
to the three-wire connection principle. Consequently, the wire resistance will be
automatically compensated. The RTD sensor/thermistor is connected across the plus
and the minus terminal, and the negative side of the RTD sensor/thermistor to the
common terminal. The leads connected to the plus and the common terminal must
be of the same type and length.
RTD sensor/
thermistor
RTD sensor/
thermistor
Fig. 4.1.4.11.-1 RTD sensor/thermistor connection
+
+
-
-
Common
+
+
-
-
Common
1MRS 752263-MUM
G
mA
DIFF
G
mA
DIFF