User Manual

3UG4 / 3RR2 monitoring relays
Manual, 02/2013, NEB927043002000/RS-AA/002
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3RR2 current monitoring relays
4
4.1 Product description
Overview
SIRIUS 3RR2 current monitoring relays are suitable for current monitoring of motors or other
loads. They are capable of two-phase or three-phase monitoring of the rms value of AC
currents, checking that the values do not overshoot or undershoot set thresholds.
The SIRIUS 3RR2 current monitoring relays are available in the two following variants:
● Basic version (3RR21): with analog setting using rotary buttons, two-phase monitoring
and CO contact.
● Basic version (3RR22): digital setting via a display, 3-phase monitoring, CO contact, and
semiconductor output; also monitors phase sequence, phase failure, ground fault and
blocking current
Whereas apparent current monitoring is primarily used in the rated torque range or for
overload, active current monitoring can be used to observe and evaluate the degree of
loading across a motor's entire torque range.
Apparent current monitoring and active current monitoring are described in more detail in
Chapter "Parameters (Page 351)."
System integration
The 3RR2 current monitoring relays have been matched to the contactors in the 3RT2 series
both electrically and mechanically and can be integrated in the feeder by means of direct
mounting. This eliminates the need for the main circuit to be wired separately and no
additional transformers are required.
For a stand-alone assembly or if an overload relay is being used at the same time, terminal
supports for stand-alone assembly are available for separate DIN rail mounting.
The current monitoring relays are available in two sizes, S00 and S0.
Accessories
The accessories have been tailored to the current monitoring relays; they can be mounted
easily and without the need for tools. The accessories are described in Chapter "Accessories
for 3RR2 current monitoring relays (Page 311)."