Switching In The Auxiliary Circuit - Siemens SIRIUS 3RT Manual

6.8

Switching in the auxiliary circuit

Applications
The 3RH2 contactor relays can be used for switching in the auxiliary circuit (controlling,
signaling, interlocking).
Thanks to their high contact reliability at low voltages and currents, the 3RH2 contactor
relays are suitable for solid-state circuits down to a lower limit of 1 mA at 17 V.
Versions
3RH2 contactor relays are available in a width of 45 mm (size S00) and can be ordered with
solenoid coils for AC or DC operation. The external design of the 4-pole 3RH21 contactor
relay is identical to that of the motor contactor in size S00 (45 mm width). In addition, 8-pole
3RH22 contactor relays can be supplied with a permanently mounted auxiliary switch block
on the front.
Rated powers
The performance range of the 4-pole 3RH21 contactor relays in size S00 extends up to 10 A
at a voltage of up to 230 V in utilization category AC-15/AC-14 and up to 10 A at 24 V DC in
utilization category DC-12/DC-13.
Auxiliary switch blocks
The 3RH2 contactor relays can be expanded by up to 4 contacts via attachable auxiliary
switch blocks.
Special version: 3RH24 latched contactor relays
In the event of a short circuit in the low-voltage system or if large drive motors are switched
on directly, the control supply voltage for the contactor relays may drop out or fall below the
permissible tolerance for a brief period. To guarantee continued operation, the
3RH24 special version of the contactor relays, with mechanical latching, may be used.
These contactor relays latch mechanically following switch-on and then remain switched on
even if there is a voltage failure. The contactor relay can be released either electrically by
means of a release solenoid, or manually by actuating the latched contactor. When the
voltage is recovered, the storage properties of the contactor relays mean that the production
program can be resumed straightaway without any resetting time. The contactor coil and the
coil of the release solenoid are both dimensioned for continuous operation. The power input
is the same for the contactor coil and the release coil. The number of auxiliary contacts can
be extended by means of auxiliary switch blocks on the front (up to 4 poles).
SIRIUS - SIRIUS 3RT Contactors/Contactor assemblies
Manual, 09/2017, A5E03656507120A/RS-AE/006
Configuration
6.8 Switching in the auxiliary circuit
105