Product Description; Introduction - Siemens SIRIUS 3RT Series System Manual

SIRIUS 3RR2 current monitoring relays

8.2 Product description

8.2 Product description
8.2.1

Introduction

Overview
SIRIUS 3RR2 current monitoring relays are suitable for current monitoring of motors or other
loads. They are capable of two- or three-phase monitoring of the rms value of AC currents,
checking that the values do not overshoot or undershoot set threshold values.
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.
The 3RR2 current monitoring relays can be integrated directly in the feeder by mounting
them on 3RT2 contactors, thereby eliminating the need for the main circuit to be wired
separately. Separate transformers are not 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.
System integration
The 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.
The current monitoring relays are available in two sizes, S00 and S0.
Connection systems
The current monitoring relays are available with the following connection system options:
● Screw-type
● Spring-loaded
Accessories
The accessories have been tailored to the current monitoring relays; they can be mounted
easily and without the need for tools.
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SIRIUS Innovations
System Manual, 01/2011, A8E56203870002-03