Table of Contents
Advertisement
Product description
3.3 Functions
3.3
Functions
Overview of the basic functions
The 3RB24 solid-state overload relay for IO‑Link offers the following basic functions:
Protective function:
• Current-dependent protection of loads against overload
• Current-dependent protection of loads against phase asymmetry
• Current-dependent protection of loads against phase failure
• Cold conductor (PTC) sensor circuit (thermistor protection)
• Protection of loads against incomplete ground faults
Motor starter function:
• Control of the relay contacts for operating the connected contactors via IO‑Link
Diagnostics and monitoring:
• Output of an analog signal DC 4 mA to DC 20 mA as an image of the flowing motor current
• Diagnostics via IO‑Link for further processing in the higher-level controller, e.g. device status
with regard to protective functions, parameterization and transfer of the measured current
value
Note
Fuses or circuit breakers must be used for short-circuit protection.
Overload protection/phase asymmetry/phase failure
The 3RB24 solid-state overload relays for IO-Link are modular in design and are supplied with
power via the IO‑Link master. The associated 3RB29 current measuring modules can be ordered
in different sizes and cover a current range of 0.3 to 630 A. This means the right current
measuring module can be selected for every application. A current setting up to 820 A is possible
in conjunction with a series transformer. The solid-state overload relays have been designed to
provide current-dependent protection for loads with normal starting and heavy starting against
impermissibly high temperature rises due to overload, phase asymmetry or phase failure. The
devices can be used as direct-on-line starters, reversing starters or, with the help of an additional
circuit, as star-delta (wye-delta) starters.
Overload, phase asymmetry or phase failure results in an increase of the motor current beyond
the set rated operational current of the motor. This increase in current is detected using a current
measuring module, and electronically analyzed by a connected 3RB24 evaluation module. The
evaluation electronics send a signal to the auxiliary contacts. The auxiliary contacts then
disconnect the contactor and the load. The break time depends on the ratio of the tripping
current to the rated operational current I
22
and is stored in the form of a tripping characteristic
e
SIRIUS 3RB24 electronic overload relay for IO-Link
Equipment Manual, 07/2022, NEB969165602000/RS-AA/003
Advertisement
Table of Contents
