Maintenance; Appendix; Applications - K-TEK MS30 Installation & Operation Manual

5.0 Maintenance

The MS30 does not require any routine maintenance in normal day to day operation.
If there is a need to take the switch out of service or disconnect it for any reason, then make sure
the circuit is de-energized or that the area is known to be non-hazardous.

6.0 Appendix

A ton of K-TEK's switch products (MS30, MS30EX, MS50) are based on magnetically operated reed switches. Since
reed switches have the inherent characteristic of very closely spaced switch contacts, it is extremely important to
protect these contacts from high voltage transients caused by inductive loads. When an inductive load is de-
energized., the collapsing magnetic field induces a high voltage of opposite polarity into itself and thus the switch .
Two basic methods exist to clamp this voltage and thus protect the switch contacts.
6.1 D.C. Applications
For D.C. applications, a diode is placed in parallel with the
inductive load (note the polarity of the diode and power sup-
ply). A 1N4001 general purpose diode is normally sufficient
to clamp the induced voltage of the inductive load to as safe
level.
6.2 A.C. Applications
For A.C. applications, a Metal Oxide Varistor (MOV transient
surge suppressor) is placed either in parallel with the switch
or the inductive load. The MOV changes from a high imped-
ance to a very low impedance when the voltage across the
MOV exceeds its rated voltage (the MOV rating must corre-
spond with the power supply voltage). For 120 VAC control
systems a typical MO would be the GE (General electric
Co.) part number V130LA10A. In either case shown, the
result is the limiting of the switch voltage to approximately
130 volts.
MS30-0200-1 Rev d (10-2010)
DCN0530
D.C. Contact Protection
A.C. Contact Protection
5