# Temperature Differential Switch

Written by Jerry Ratzlaff on . Posted in Temperature Instrument

A temperature differential switch, abbreviated as TDS, contains the same functionality of a temperature switch with the exception that it is looking for the difference of temperature rather than a single input.  It might be used to measure liquid flow,level or interface by sensing changes in the thermal heat transfer characteristics of the media where it is located.

Note that like a pressure switch, a temperature switch is different than a flow transmitter in that a temperature switch's sole function is to provide a binary TRUE or FALSE into the PLC. This approach simplifies programming.

## Configuration and Alarms

Alarms in the PLC can be:

• $$DTSH$$ - Differential Temperature Switch High
• $$DTSL$$ - Differential Temperature Switch Low