Troubleshooting Procedures
3.9 Deadband Too Small
PS2 Troubleshooting Guide
24 Service Manual, 03/2017, A5E36661550-AA
● If deadband value is too large for the application, the PS2 is compensating to prevent
valve oscillations. These valve oscillations could be:
– Too much stiction; see Stiction (Page 36).
– Too many step changes from process controller. This is a process control loop issue.
Discuss issue with operator and/or plant process engineer.
– Loose linkage, see Loose Linkage (Page 29).
Too small a fixed deadband value can cause valve oscillations, see Dead Band Too
Small (Page 24).
● From AUT or MAN mode, press
button for 5 seconds. Now observe the parameter
name in the lower right corner.
● Continue to press the
button until "DEBA" parameter is reached.
● Use
and/or buttons to decrease deadband value.
● To return to Automatic mode, press and hold the
button for 5 seconds.
● The unit will now be in Manual mode.
● Press the
button one time to return to Automatic mode.
The deadband of the PS2 is the area around setpoint when the PS2 stops working to get
closer to setpoint. For example, if the deadband value is 0.1 %, and the setpoint is 70 %, the
PS2 will work the piezo valves to get within the following position range: 69.9 % to 70.1 %.
Thus, the PS2 will continuously work to get within this deadband range. However, if the
mechanics of the actuator and/or valve cannot achieve this precise position, the PS2 will
continuously hunt or oscillate around the setpoint position.
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