Zero Speed Switch Working Principle

Zero Speed Switch

Now a days in material handling plants under/Over speed monitor is one of the essential control and safety device.

Application :

Electronic Speed Monitor is used to monitor speed of conveyors, crushers, rolling mills, agitators, mixers, stirrers, screw conveyors, and other industrial machinery. This device actuates relay contacts at preset speed. Using these contacts desired control action such as zero speed protection/ under speed protection/ over speed protection can be achieved.

Advantages :

  • It Senses speed by non-contact way. Hence no moving parts.
  • No wear and tears of rollers or misalignment of couplings.
  • Easy speed setting.
  • Built in initial by-pass time delay arrangement.
  • Speed setting possible from 1 RPM to 5000 RPM in optional ranges.
  • Totally enclosed sensor, works in presence of dust, dirt water, oil & chemicals.
  • Direction sensing and speed monitoring of various locations from single point is possible.
  • Intrinsically Safe Sensors and speed switches with Flameproof Enclosures are available for use in Hazardous area.

Operation :

The basic principle of speed monitor is comparison of pulses received from sensor with standard pulses. The unit consists of two parts: CONTROL UNIT and “SENSOR PROBE”. The sensor is to be installed with its sensing face in close proximity of rotating object. On this object, flags are to be fixed.

The sensor products strong electromagnetic waves, which get disturbed by the flags, giving rise to corresponding pulses. These pulses are fed to the control unit where they are compared with standard pulses to sense the speed.


Output :

The control unit incorporates an output relay. This relay will operate at preset speed giving 2C/O contacts of 5 Amp 240 VAC resistive.