Pressure Switch

Written by Jerry Ratzlaff on . Posted in Pressure Instrument

A pressure switch provides a discrete input to the PLC.  The pressure switch is typically used as a method of control in tanks, vessels and over all process control.   

Note that a pressure switch is different than a pressure transmitter in that a pressure switches sole function is to provide a binary TRUE or FALSE into the PLC.  This approach simplifies programming.  

  • Abbreviated as PS

Types of Pressure Switches

  • Mechanical Deflection
  • Piston
  • Strain Gauge
  • Semiconductor Piezoresistive
  • Piezoelectric
  • Thin Film
  • Variable Capacitance

Configuration and Alarms

Configuration (Normal State):

  • NO - Normally Open
  • NC - Normally Closed

Alarms in the PLC can be:

  • PSH - Pressure Switch High
  • PSL - Pressure Switch Low
  • PSHL - Pressure Switch High/Low