Dps

 DPS ( Differential Pressure Switch ).

Dps is the other name is "Air Flow Switch."

It's works to monitor Air filter Dirty/Clean, Air Flow/No Air Flow, Fan Belt, and Air Pressure inside the Duct, AHU etc. 

Supply Voltage :- 24v or 250v 

How to Service it?

To Clean pipe throw Air Pressure. 

How to check Faulty ?

To check Continuty in NC pole & NO pole.

Why we apply this device ?

Its helps us to show status about Air Flow in the BMS Display & DDC Panel.