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Level Controller: Possible to Use with 15 kΩ or less, but may Cause Reset Failure

FAQ No. FAQ01480

Primary Contents

Question

Why do the specifications for the High-sensitivity 61F Floatless Level Controller say, "possible to use with 15 kOHM or less, however, this may cause reset failure"?

Answer

The interelectrode voltage of 61F is AC. This generates a floating capacitance between ground and the cable that connects the electrode bar to 61F body. The current that flows due to this cable-to-ground floating capacitance causes the reset failure.

The reset current for 61F High-sensitivity Controller is 0.05 mA AC min. If the current flowing through the ground capacity is, for example, 0.1 mA, there will be a reset failure because of the reset current (0.05 mA AC min.) even when there is no liquid between the electrodes.

Countermeasures:

1.Shorten the cable between the Electrode and 61F Controller. (For the 61F-GP-N8 High-sensitivity Controller, use a 0.75-mm2, 3-conductor, cabtyre cable that is 50 m or less in length.)

2.Use a General-purpose Controller for applications where the liquid resistance can be detected at ordinary sensitivity (0 to 4 kOHM).