WIKA PSD-31 - Manual (Page 23)

23 WIKA operating instructions pressure switch model PSD-3x
GB
11430486.06 02/2012 GB/D/F/E
6.5 Switching functions
Hysteresis function
If the system pressure fluctuates around the set point, the hysteresis
keeps the switching status of the outputs stable. With increasing system
pressure, the output switches when reaching the switch point (SP).
■ Contact normally open (HNO): active
■ Contact normally closed (HNC): inactive
With system pressure falling again, the output will not switch back
before the reset point (RP) is reached.
■ Contact normally open (HNO): inactive
■ Contact normally closed (HNC): active
Window function
The window function allows for the control of a defined range.
When the system pressure is between window High (FH) and window
Low (FL), the output switches on.
■ Contact normally open (FNO): active
■ Contact normally closed (FNC): inactive
When the system pressure is outside window High (FH) and window
Low (FL), the output does not switch on.
■ Contact normally open (FNO): inactive
■ Contact normally closed (FNC): active
6. Commissioning, operation
Fig.: Hysteresis function
Fig.: Window function