User Manual

SIRIUS 3RU2/3RB3 overload relays
5.2 Product description
SIRIUS Innovations
490 System Manual, 01/2011, A8E56203870002-03
5.2.4 3RU21 thermal overload relays
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1 Connection for contactor mounting:
In terms of their electrical and mechanical features and their design, these pins are perfectly
compatible with the contactors and soft starters for the direct mounting of overload relays.
Stand-alone assembly is also an option (in conjunction with a stand-alone assembly module).
2 Switch position indicator and TEST function for wiring:
Indicates a trip and facilitates testing of the wiring.
3 Motor current setting:
The large rotary button provides an easy means of setting the device to the rated motor
current.
4 Control circuit terminal::
A screw-type, spring-loaded or ring cable lug connection system can be used to connect the
control circuit.
Information about the date of manufacture and product version appears below.
5 Main circuit terminal:
A screw-type, spring-loaded or ring cable lug connection system can be used to connect the
main circuit terminal.
6 STOP button:
Pressing the button opens the NC contact, thereby disconnecting the downstream contactor.
The NC contact closes again when the button is released.
7 Selector switch for manual/automatic RESET and RESET button:
This switch is used to choose between manual and automatic RESET. A device set to manual
RESET can be reset locally by pressing the RESET button. The device can be reset remotely
using the RESET modules (accessories) which are compatible for use with all sizes.
8 Label
Figure 5-1 Equipment, 3RU21 overload relay
A sealable transparent cover can be optionally mounted (accessory). It stops the motor
setting being tampered with.
Auxiliary contacts
3RU21 thermal overload relays are equipped with an NO contact for the "tripped" message
and an NC contact for disconnecting the contactor.