ABB REM 610 Technical Reference Manual page 44

REM 610 REM 610
44
Motor Protection Relay
Technical Reference Manual - ANSI Version
RTD6 can be used to measure the ambient temperature for the thermal
protection element. In this case, RTD6A and RTD6T 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.
For as long as the emergency start is activated, RTD1...6T will be
increased by 10 per cent.
Temperature protection using thermistors
REM 610 supports PTC thermistors.
When input RTD1/RTD4 is used with thermistors, a trip value, PTC1/PTC2, is set
for the respective input.
When the resistance of the thermistor exceeds the set trip value, PTC1/PTC2,
element 49/38-1/49/38-2 will generate a trip signal on expiration of the 2 s' fixed
operate time.
The trip signal from 49/38-1/49/38-2 will be reset in 800 ms after the resistance has
fallen below set trip value PTC1/PTC2>.
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.
1MRS755537