Support website

When specific measurement problems occur, first check the specific support pages of this Support website to test the electrode and measurement:

• pH problems
• EC problems
• Dissolved Oxygen

In case of correct measurements when following the T.A.F. but erroneous when the electrode is placed in the process fluid, test the following points:

1. Try measuring the process solution in a glass beaker. If the error remains,
   • check the electrode's compatibility to the solution.
   • try a new electrode. Older electrodes often need to be replaced as the reference electrode could be poisoned. This may not always be noticed when measuring in buffers.
2. Check all connections (mains, controller and all devices included in the process) for a proper earthing. If there are voltage differences (DC and/or AC) on the different earthings, try to connect them all to the same earth connection.
3. Immerse an earthing rod close to the electrode to avoid ground loops. Connect the rod to the Mass terminal of the screw terminal connector. Does the error remain? (If so, proceed with the next step)
4. Disconnect everything (relays, analogue outputs and digital ports) from the instrument except for the electrode and the mains power.
   • If the error has disappeared, reconnect the disconnected parts one by one to see when the error returns.
   • Test the connected device which causes the error for its good operation and electrical influence to the process fluid. If this cannot be solved by placing an earthing rod, revise the installation schematics to avoid current loops to the electrode.
   • If the error remains, measure with a voltmeter the voltage between the Mass terminal and the electrode reference terminal (CHAN-):
     • DC = —– V ?
     • AC = —– V ?