Functions - Siemens SIRIUS 3RN2 Manual

Functions

The SIRIUS 3RN2 thermistor motor protection relays operate in accordance with the closed-
circuit principle and therefore monitor themselves for loss of supply voltage. The exceptions
are the warning output on device 3RN2023, which always works on the open-circuit
principle, and the bistable relays of the 3RN2012-.BW31, which always retain the last
switching state. A micro-interruption in the power supply of less than 30 ms does not change
the status of the output relays. In the event of longer voltage dips or an extremely slow
increase in the supply voltage, the devices may enter into a system stop in which the output
relays drop out (exception: 3RN2012-.BW31) and the devices are only functional again
after restarting the system. The flashing red LED (TRIPPED) indicates a system stop.
1)
NOTICE
Restart
Disconnect the devices from the supply voltage for at least 1 s before restarting the system.
The 3RN2011, 3RN2012, 3RN2013, and 3RN2023 devices are additionally equipped with
wire-break and short-circuit detection in the sensor circuit.
3RN2000 compact unit
The compact unit, which is only 17.5 mm wide, is equipped with a red LED (TRIPPED) for
the tripped indicator and a changeover contact. After the unit has tripped, it is automatically
reset once the thermistors have cooled down. The root of the changeover contact is
connected to the control voltage (terminal 11 is connected to terminal A1). This unit is
particularly suitable in circuits in which the control circuit and signaling circuit have the same
potential, e.g. in local control cabinets.
SIRIUS 3RN2 thermistor motor protection relay
Manual, 10/2016, A5E34244868002A/RS-AA/001
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