Burkert 8756, Operating Instructions Manual

Page: 76 / 88

Type 8756
Troubleshooting
english 76
10.2.10 Unstable measured value (MFC with
proportional valve or for modular
actuator)
Identify the cause to solve the problem:
Cause Solution
You have not connected the
functional earth (FE) properly.
To connect the functional
earth, use a green-and-yel-
low cable that is as short as
possible. And the cable
cross-section must be at
least equal to the cross sec-
tion of the power-supply
cable. Refer to chapter:
Connect the functional
earth [
}
44]
The residual ripple on the
voltage supply is too high.
Use a supply voltage that
conforms to the technical
data given in chapter:
Elec-
trical data [
}
29]
The controller is unstable.
Run the Autotune function to
adapt to the operating con-
ditions. Refert to chapter:
Optimise the closed-loop
control parameters (MFC)
[
}
59]
Cause Solution
The product is caused to vi-
brate.
Run the Autotune function to
adapt to the operating con-
ditions. Refer to chapter:
Optimise the closed-loop
control parameters (MFC)
[
}
59]
Reduce the input pressure
or contact the manufacturer.
10.2.11 Set-point value at 0 %, but operating
fluid still flows (MFC Analogue with
pump)
Identify the cause to solve the problem:
Cause Solution
There is pressure upstream the
pump. The pressure makes the
fluid flow. Pressure can be due
to an incorrect position of the
fluid container.
Install the fluid container in
such a way that no pressure
is generated upstream the
pump.