Siemens 3UG4 - 3 RR2 current monitoring relays; 4.1 Product description

3UG4 / 3RR2 monitoring relays
Manual, 05/2016, NEB927043002000/RS-AC/004
45
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.
SIRIUS 3RR2 current monitoring relays are available in the 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
● Version for IO-Link (3RR24): same as standard version, but additionally with IO-Link
interface for direct interfacing to a PLC for remote parameterization, remote diagnostics,
cyclic transfer of measured values, support of the parameter server functionality of IO-
Link (with master as from specification V1.1), with integrated runtime and switching cycle
counter
You can find further information in the Manual "3UG48/3RR24 Monitoring Relays for IO-
Link".
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 the
Chapter "Parameters (Page 363)".