SHD30 / SHD30-45

  • Normally open and normally closed overspeed alarm or shutdown switch (standard)
  • RPM data and power supplied by magnetic pickup or capacitor discharge (cd) ignition
  • accurate to ±0.5% of display reading
  • hours can be preset and reset to zero
  • Approved for Class I, Division 2, Groups C & D hazardous areas

FW Murphy Production Controls offers support for all our products. If you are unable to find the product that you need, please call us at 918-957-1000.

Stage V: 
Product Overview: 

The SHD30 and SHD30-45 are microprocessor-based tachometers with hourmeter and an overspeed trip point. The trip point can be connected as either a form C relay output or as a normally open SCR output for alarm or shutdown on overspeed.

The SHD30 features a panel-mounting design, plastic enclosure that is 5-1/16 (129 mm) long and 4-1/4 in. (108 mm) high.

The SHD30-45 has the same enclosure, but it also has a backplate with studs to mount like an OPLFC. The SHD30 models power and RPM data are supplied by either a magnetic pickup or a capacitor discharge (CD) ignition. The hourmeter is adjustable to a preset time and resettable to zero. Should power be lost, onboard batteries maintain the run hours display and allow for resetting the overspeed relay output.

When a tach signal is present the SHD30 models display RPM. When a tach signal is not present, the display is blank unless the Read Hours membrane key on the faceplate is pressed and held.

The five-digit, liquid crystal display is updated every second. The run hours, overspeed set point and current pulses per engine revolution can be displayed by manipulating the membrane switches. Run hours can be displayed even after power is lost. The run hours display can be configured to alternate with the RPM display.

Ease of Calibration

The SHD30 models calibration is accomplished by entering the number of pulses per engine revolution using the Pulses per Revolution and Overspeed Set point membrane keys on the faceplate. The number of pulses is determined by the number of cylinders, cycles and ignition features. It is also determined by the number of ring gear teeth of the engine’s flywheel on a magnetic pickup system.

Presetting and resetting running hours is done from the back and front of the SHD30 models.


  • Gas Compressors
  • Oil Field Equipment

Speed Sensors and Instruments