3RU11, 3RB10, and 3RB12 overload relays
SIRIUS System Manual
GWA 4NEB 430 0999-02b
4-11
3RB10 electronic overload relays
Description
• Tripping classes 10 and 20
• For motor currents of up to 100 A
• Low waste heat, energy-saving
• Wide setting ranges for simple configuration, selection, and less storage
• Extremely low energy requirements: approx. 50 mW
Electronic overload relays work with current transformers that provide a
measurement signal that is evaluated by an electronic circuit. They are
designed for sinusoidal 50/60 Hz supply voltages.
The 3RB10 electronic overload relay, like the 3RU11 thermal overload relay,
can be built directly into the motor feeder but hardly causes any heat loss
thanks to the electronic measurement system. The tripping classes 10 (for
normal starting) and 20 (for heavy starting) are implemented with the 3RB10
electronic overload relay.
The current range of the electronic overload relays can be set to the motor
current at a ratio of 1:4 (lower to upper current mark). Up to 6 motor ratings
are covered by a single range, and a current range of 0.1 to 100 A is covered
by only 7 setting ranges.
3RB12 electronic overload relays
Description
The 3RB12 electronic overload relays are suitable when there are high
motor protection requirements on account of the following features:
• Tripping classes 5/10/15/20/25/30 settable
• For motor currents of up to 820 A
• Evaluation of PTC thermistors
• Analog output signal of 4 mA to 20 mA for current detection (insensitive
to harmonics)
• High accuracy of the tripping characteristic with a tolerance of <
±
10 %
• Ground fault detection internally and externally through summation cur-
rent transformer
• Insensitive to external influences such as vibrations, different cable cross-
sections, temperature fluctuations, corrosive environments or aging
The 3RB12 electronic overload relay can be used for everything from easy
starting (CLASS 5) to very heavy starting (CLASS 30). The tripping class can
be set in steps to the relevant motor starting time. In addition, the 3RB12 is
equipped with inputs for PTC thermistors, which make it a fully protected
motor device. Additional functions such as ground fault detection and an
analog output signal are also possible. It is available in 4 sizes from 1.25 to
820 A.
It is triggered in the event of an overload, current imbalance, phase loss, or
a blocked rotor.
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