Monitoring relays

SIRIUS monitoring relays provide reliable protection for machines and plants. Current measured values or conclusive diagnostics messages are indicated on the device display. For easy connection to the controller, most monitoring relays are also available with an IO-Link interface. We offer monitoring relays for electrical and mechanical variables, as well as temperature monitoring according to your requirements. Our extensive relay range has been expanded to include a multifunctional load monitoring relay for DC applications. This is a compact device in which functions such as measuring, monitoring and data transfer are bundled.

Technical specifications for monitoring relays

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SIRIUS monitoring relays - one range for every application

Come and see for yourself and get to know the new compact, multifunctional DC load monitoring relay.


DC load monitoring

SIRIUS 3UG546 DC load monitoring

The purpose of the 3UG546 DC load monitoring relay is to monitor DC applications in industrial applications. It monitors the direct current (DC load current circuit), voltage, and actual power for overshooting or undershooting of set limit values in one or two channels. This means that current, voltage and power can be monitored separately.


Besides providing detailed error diagnostics, the integrated energy counters, operating hour counters and switching cycle counters can also be read out and reset, making it possible to reliably maintain the system. The relay identifies the direction of current flow so that the quantities of energy stored in or drawn from a battery, for example, can be recorded separately.


The 3UG546 DC load monitoring relay can be fully parameterized via Profinet and transfers the measuring and metering values and diagnostic messages via Profinet to the control system. After the signaling or switching function is performed via an internal relay output, reliable error responses are also possible without Profinet.


It covers a wide operating voltage range from 0 to 800 V. In this current range two versions are available: 22.5 mm wide: 2x8 A / 1x16 A and 45 mm wide: up to 63 A.


Monitoring of line, current, voltage, power factor and active current, residual current, insulation, level, and speed

SIRIUS 3UG4 monitoring relays for electrical and mechanical variables

The SIRIUS 3UG4 monitoring relays monitor the most diverse electrical parameters in the feeder, and provide reliable protection against damage in the plant. They not only feature freely parameterizable threshold values and manifold adjustment options, but also provide conclusive diagnostics and are even able to correct an incorrect phase sequence autonomously. Numerous versions are also available with IO-Link interface for connection to the controller.


The SIRIUS 3UG4 monitoring relays also monitor mechanical variables.

The level monitoring relays ensure reliable 1 or 2-point controls and alarm messages in the event of overflow or dry running.

The speed monitoring relays check whether the nominal speed of motors, shafts or powered wheels is exceeded or not reached. Moreover, the relays are suitable for all functions requiring the monitoring of a continuous pulse signal. Optionally with IO-Link connection.


For direct mounting on contactors for multi-phase current monitoring

SIRIUS 3RR2 monitoring relays for electrical variables

As well as monitoring of motors or other loads, the SIRIUS 3RR2 current monitoring relays are especially suitable for optimum current monitoring of the overall plant or of the powered process. Thus, load shedding or overload of the motor, for example, is detected quickly and reported early. The 3RR2 monitoring relay for current monitoring is integrated directly in the load feeder. It simply plugs into the contactor. Also available with IO-Link connection.


Protection against overheating in windings

SIRIUS 3RN2 thermistor motor protection relays

Thermistor motor protection relays provide decisive benefits in cases in which current-dependent protection using either a circuit breaker or an overload relay is not the perfect solution: In certain cases, overheating can occur without being detected by the thermal image in the circuit breaker/overload relay, for example in the case of heavy starting, operation with frequency converters or frequent switching, strong braking operations or restricted cooling. The 3RN2 thermistor motor protection relays provide a reliable protection against motor overheating by measuring the temperature at the hot points in the inside of the motor. They monitor the winding temperature of motors directly.


Temperature monitoring

SIRIUS 3RS1/2 temperature monitoring relays

The temperature of solid, liquid and gaseous media represents the most frequently measured parameter in industrial applications. The SIRIUS 3RS1 temperature monitoring relays monitor process temperatures just as reliably as the temperatures in control cabinets or of motors - with up to three sensors at the same time where required.  These are available in analog or digital versions (also with IO-Link).


Analogically adjustable: The temperature is recorded by sensors in the medium, evaluated by the device, and monitored to determine whether it is within the upper and lower temperature limits. When the threshold values are reached, the output relay switches on or off depending on the parameterization.


Digitally adjustable: The temperature is monitored to evaluate whether it is above or below a certain value or within a specific operating range (window function). The devices also present a good alternative to temperature controllers in the low-end range.

We offer you different monitoring relays, depending on your requirements

Videos on functions of the monitoring relays

  • Line and single-phase voltage monitoring (also via IO-Link)
  • Multi-phase current monitoring (also via IO-Link)
  • Single-phase current monitoring or power factor and active current monitoring (also for IO-Link)
  • Level monitoring
  • Speed monitoring