Wiring the Siemens Combustion Controls SQM4 Synchro for 4-20 mA Modulation

This video explains the simple wiring of the most common SQM4 Synchro actuator from Siemens Combustion Controls.  The "5" board (SQM4x.x5x...) is used with a 4-20mA signal and offers a fantastic alternative to outdated MODulating actuators.

The Siemens SQM4 Synchro is a cost effective modulating actuator with up to 160 in-lbs and 12 or 25 second drive times for 90 degrees. The SQM4 Synchro is suited for driving oil pressure controller, butterfly valves, dampers or for use on other applications that require rotary motion.


  • NEMA 4 – No need for weather shields
  • No restrictions on mounting orientation – No more elaborate linkages to keep the shaft horizontal!
  • The modulating input versions accept 2-10 Vdc, 4-20 mA or 0-135 ohm control signals
Areas of application are oil and gas burners of medium to higher capacity as well as
thermal process plants.

For more information contact Combustion Tech. Call 800-327-1831 or visit https://combustion-tech.net.