SIRIUS 3RU2/3RB3 overload relays
5.8 Operation
SIRIUS Innovations
518 System Manual, 01/2011, A8E56203870002-03
Recovery time following overload release
This time gives the load a chance to cool down.
● 3RU21 thermal overload relays
The device cannot be reset until the bimetal strips have cooled down. The recovery time
is dependent upon the tripping characteristic curve and the extent of the tripping current.
● 3RB30/3RB31 solid-state overload relays
In the case of the 3RB30/3RB31 solid-state overload relays, the recovery time is stored
as a fixed value and is 3 minutes following a current-dependent release with automatic
RESET selected.
If manual RESET is selected, the 3RB30/3RB31 relays can be reset immediately after
tripping.
Setting the RESET function on the 3RU21 thermal overload relay
On the 3RU21 thermal overload relay, automatic and manual resetting is selected by
pressing and turning the blue button (RESET button). The figure below shows how to switch
between automatic and manual reset on the 3RU21 thermal overload relay, size S0.
Table 5- 18 Switching between manual and automatic on the 3RU21 thermal overload relay
Step Operating instruction Figure
1 Press the blue RESET button down with a
screwdriver.
2 Turn the blue RESET button to M (manual
reset) or A (automatic reset).
MANUAL
AUTO
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