Coupling relays and signal converters

When controllers with their standard inputs and outputs reach their limits, then powerful coupling relays and signal converters are required. A wide selection of coupling relays and signal converters is available for electrical isolation of I/Os and PLC inputs and outputs, signal amplification or reproduction, as well as conversion to different voltage levels or signal forms. We offer the appropriate solution for all requirements.

Technical specifications for coupling relays and signal converters

Industry Mall

Depending on your requirements, we offer you a wide range of coupling relays and signal converters

3RQ2 coupling relays

Universal with wide voltage range

SIRIUS 3RQ2 coupling relays featuring a wide-range supply voltage for universal use

The SIRIUS 3RQ2 coupling relays with their new high-quality industrial enclosure in a modern titanium gray, ensure a user-friendly connection system with removable terminals. Outstanding features also include a wide-range supply voltage of 24 to 240 V AC/DC for global use.


  • Variants with one to three changeover contacts and wide-range supply voltage (24 to 240 V AC/DC)
  • Variants with hard gold-plated contacts for switching currents in the lower mA range
  • International standards and certifications such as CE, UL/CSA, EAC, with confirmations for railway operation

3RQ3 coupling relays

Compact with relay and semiconductor output

SIRIUS 3RQ3 coupling relays for space-optimized use in the control cabinet

The SIRIUS 3RQ3 coupling relays with a width of only 6.2 mm and low overall depth/height are ideal for narrow tier spacing or in flat switchboxes. They are available with either relay or semiconductor output.


  • Permanently soldered relays for enhanced contact reliability
  • Plug-in relays to ensure fast relay replacement with permanent wiring
  • Semiconductor output for an extremely long electrical service life with an unlimited number of switching cycles
  • Universal bridging option using connecting combs for all terminals

LZS plug-in relays

Powerful and versatile

SIRIUS LZS plug-in relays

LZS plug-in relays can be ordered as complete units or as individual components and are available with screw or push-in terminals. Available with LED (with surge suppression in 24VDC version) and retainer/ejector clip, changeover contacts (1CO to 4CO) and coil voltages from 12VDC to 230VAC.

  • Tested AC-15 and DC-13 switching capacity
  • Available coil voltages: 24 V DC, 24 V AC, 115 V AC, 230 V AC
  • Hard gold-plated contacts for optimum interaction with electronic controls

3TX71 plug-in relays

Powerful and versatile

3TX71 plug-in relays

3TX71 relays are available as open power, enclosed power and plug-in style relays. The plug-in family includes basic, premium and bifurcated styles, screw terminals only, and are available with LED (surge suppression in 24VDC version), mechanical flag and push-to-test options. They must be ordered as individual components and their contacts range from 3 to 15 amps. 

Open power relays offer switching up to 40 amps and are available with optional metal cover. Enclosed power relays are available up to 30 amps.


Voltage ranges:

  • plug-in style: from 12VDC to 240VAC
  • enclosed style: from 24VAC/DC to 230VAC
  • open style: from 12VDC to 240VAC

3RS70 signal converters

For analog standard and universal signals

SIRIUS 3RS70 signal converters in narrow compact design

3RS70 signal converters are mainly used to electrically isolate and convert analog signals. The frequency outputs implemented offer further applications. Only minimal space required on the standard mounting rail due to the narrow design of just 6.2 mm and reduced depth and height of the enclosure, ideal for flat switchboxes and control cabinets with small gaps between tiers.


Reduced device variance resulting from exclusive use of 3-way separation. For the 3-way separation, each circuit is galvanically separated from the other circuits, i.e. input, output, and supply voltage do not have equipotential bonding.

3TG10 power relays

For performance range below S00

Compact SIRIUS 3TG10 power relays for switching of high loads

3TG10 power relays are the ideal option wherever small, low-noise relays or contactors are required. They are suitable for simple controllers and for applications that do not require an overload relay and only need one auxiliary switch – but which therefore need more switching power, higher switching voltage, and a longer service life.


  • Can be mounted in any position, hum-free
  • Narrow width of just 36 mm
  • Integrated auxiliary switch
  • Protective separation
  • Integrated overvoltage damping