Accessories
4.3 Control and signaling accessories
3WA1 air circuit breaker
236 Equipment Manual, 02/2023, 92310000002-06
Undervoltage release (UVR/UVR-t)
The undervoltage release trips the circuit breaker if the control voltage U
S
is unavailable
or drops to between 70% and 35% of its normal value (in compliance with the relevant
standard) and locks it to prevent reclosing until the auxiliary voltage is restored. The
circuit breaker can then be reclosed mechanically or electrically. The undervoltage
release does not need to be reset for this purpose.
If the undervoltage release is delayed, the circuit breaker only trips if the duration of the
undervoltage is greater than or equal to the delay time. The undervoltage release
therefore prevents tripping of the circuit breaker in the event of a short-time voltage dip
or voltage failure.
The undervoltage release can be used for:
• Safe remote-controlled tripping
• Interlocking, to prevent closing
• Checking the voltage in the primary and secondary circuits
The undervoltage release is supplied with voltage via the secondary disconnect terminal
system.
It is available in two versions:
• Undervoltage release UVR:
Tripping occurs instantaneously or with a short-time delay, see Chapter Technical
specifications (Page 237).
• Undervoltage release UVR-t:
Tripping occurs with an adjustable delay time from 0.2 to 3.2 s.
Note
The circuit breaker with an undervoltage release can be closed at
a control voltage from
U
S
on the undervoltage release.
Note
Undervoltage release UVR or UVR
-t and shunt trip ST2 are mounted in the same
not possible to use these accessories simultaneously.
The undervoltage release can be retrofit.
For more information, refer to the operating instructions on the internet
(https://support.industry.siemens.com/cs/ww/en/view/109783975).
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