Frequently Asked Questions about Magneto-Electric Rotation Detector

Question number FAQ-0855

Precautions when installing multiple MP-981 units:

(Question clarification)

Four MP981s were mounted in a row on a single gear. The fixing jig was made of SUS400. The two outer ones worked even with a gap of 1mm or more from the gear, but the two inner ones did not work with a 1mm gap, and only worked with a 0.8mm gap. Why?

In conclusion, since SUS400 is a magnetic material, please change it to a non-magnetic material.

The MP-981 has a magnet at its tip. It forms a magnetic circuit between the MP and the peaks and valleys of the gear, and detects changes in that magnetic field.
Therefore, if magnetic materials are used for mounting, the magnetism between the gears tends to weaken, resulting in reduced sensitivity.
In practice, they are mostly used with iron fasteners, but when using multiple units, the gap between them may need to be adjusted to be closer due to the magnetic influence between them.

Please refer to the instruction manual for further details. The following are important usage precautions.

The detection gear is made of ferromagnetic material and has a tooth width of 3 mm or more within modules 1 to 3.

The MP981 mounting jig is made of non-magnetic material and is fixed in place to prevent movement due to vibration, etc.

Attach it to the gear, aligning it with the alignment mark on the MP.

When installing multiple MPs, leave a gap of 35mm or more between them.

In alternating strong magnetic fields (environments with magnetic field changes), magnetic circuits tend to become unstable, and this can affect detection, sometimes resulting in a failure to detect signals.
(For large AC motors, please consider installing them in a location less susceptible to magnetic field effects.)

It is not suitable for precise position detection.
(When detecting protrusions, there is variability in the relationship between the protrusion position and the signal.)

Last updated: 2000-04-10