Tips For Extending The Life Of Reed Contacts - Hydac TankConditioner TC Mode D'emploi

Shown here as an example:
Top contact housing = L2 (yellow) = rising NC
Bottom contact housing = L1 (green) = rising NO
The contact logic assumes that the fl uid level switch is installed in an empty
tank, i. e. after fi lling it is in the operating position.
Hand-tighten the plastic screws to secure the contact.
After positioning the contacts, push the contact strip back into
the sensor tube.
Plug the adaptor plug back onto the contact strip. When doing this ensure that
the adaptor plug is plugged into the contact strip correctly. This is indicated by
the red mark on the adaptor plug and the contact strip.
Screw the fl ange cover and gasket onto the fl ange housing.
Secure the fi lter housing using the mounting screws and screw on the fi lter cap
and the fi lter element.
4.4.2 Version /-S44
On versions with continuous fl uid level measurement, no alterations can be
made. They are factory set.
All types in this series supply continuous analogue signals 4 - 20 mA, where
normally 4 mA is the lowest point and 20 mA is the highest point for the level
(cf. Point 4.3 Factory settings of the fl uid level contacts).
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L2
L1

4.5 Tips for extending the life of reed contacts

Reed contacts have a long service life and very reliable components because
of their design. Nevertheless, please note the following:
Contact protection
Excessive inductive loads which generate a high inverse voltage when a reed
switch is opened, can be prevented by using the following circuit.
DC voltage: Protective diode parallel to the load
Contact
+
–
Load
Protective diode
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