Accessories
9.6 OFF-delay device
SIRIUS - SIRIUS 3RT Contactors/Contactor assemblies
320 Manual, 09/2017, A5E03656507120A/RS-AE/006
The OFF-delay device prevents a contactor from dropping out unintentionally when there is a
short-time voltage dip or voltage failure. The OFF-delay device supplies a downstream, DC-
operated contactor with the necessary energy during a voltage dip, ensuring that the
contactor does not drop out. The 3RT2916-. OFF-delay devices have been specially adapted
to the 3RT contactors (sizes S00 to S3) and the 3RH21 contactor relays (size S00), and are
available in the versions shown below.
Note
OFF-delay device requires DC contactor or an AC/DC contactor
The OFF
-delay device can be controlled with AC or with DC. However, it always requires a
ntactor or an AC/DC contactor
Table 9- 22 Versions of the OFF-delay device
Control voltage of the OFF-delay device
The OFF-delay device operates without external voltage on a capacitive basis and can be
energized with either AC or DC (24 V version for DC operation only). Voltage matching is
only required for AC operation and is performed using a rectifier bridge.
A contactor opens after a delay when the capacitors integrated in the OFF-delay device are
switched in parallel to the contactor's magnet coil. In the event of voltage failures, the
capacitors discharge via the magnet coil, thus delaying opening of the contactor.
If the command devices are located upstream of the OFF-delay device in the circuit, the
device will be activated with every opening operation. If the activation takes place
downstream of the OFF-delay device, an OFF-delay only applies if the line voltage fails. The
mean OFF-delay value is around 1.5 times the specified minimum time.
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