Overload Relays
5
Siemens · 2011
General data
1) The SIRIUS 3RU11 thermal overload relays use a bimetal contactor and
therefore do not require a control supply voltage.
Features Benefits 3RU11 3RB20/3RB21 3RB22/3RB23
Other features
Internal power supply • Eliminates the need for configuration and connec-
ting an additional control circuit
--
1)
✔ --
Variable adjustment of the trip clas-
ses
(The required trip class can be adjusted
by means of a rotary switch depending
on the current start-up condition.)
• Reduces the number of variants
• Minimizes the configuring outlay and costs
• Minimizes storage overhead, storage costs, and
tied-up capital
-- ✔
(only 3RB21)
✔
Overload warning • Indicates imminent tripping of the relay directly on
the device due to overload, phase unbalance or
phase failure
• Allows the imminent tripping of the relay to be
signaled
• Allows measures to be taken in time in the event of
continuous inverse-time delayed overloads
• Eliminates the need for an additional device
• Saves space in the control cabinet
• Reduces wiring outlay and costs
-- -- ✔
Analog output • Allows the output of an analog output signal for ac-
tuating moving-coil instruments, feeding program-
mable logic controllers or transfer to bus systems
• Eliminates the need for an additional measuring
transducer and signal converter
• Saves space in the control cabinet
• Reduces wiring outlay and costs
-- -- ✔
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