Mechanical pressure switches are often supplied with a factory-set switch point. Nevertheless, some users desire to get this to configuration themselves, as, for instance, the pressure conditions in the application form can change. In the case of pressure switches with a measuring element in a bellows, diaphragm or piston design, the manual setting of the switch point, reset point or hysteresis (with respect to the model) requires a certain amount of effort. Nonetheless it?s not witchcraft. This short article explains, step-by-step, how to take action.
Users need the next equipment: a pressure source (e.g. a dead-weight tester), a control pressure gauge, a continuity tester or perhaps a control lamp in addition to a tool for the adjustment screw (incidentally, WIKA supplies the correct Allen key using its instruments; the standard screwdriver is sufficient for setting the hysteresis).
Setting plan view for the model PSM02 mechanical pressure switch from WIKA. The pin assignment 1 and 3 (small picture) corresponds to the switching function ?normally closed?, the assignment 2 and 3 will be for ?normally open?.
Setting of the switch point
First, screw the pressure switch in to the pressure source connection and connect its electrical connections to the continuity tester or control lamp.
Turn the adjustment screw for the switch point in completely. This sets the switch point to the highest possible value.
Now apply the required switching pressure to the pressure switch before control pressure gauge indicates the worthiness.
After that, turn the adjustment screw out until the instrument switches and the continuity tester or the control lamp reacts.
Then lower Backstabbing before pressure switch switches back and increase it again to check on the switch point. If necessary, the switch point must be corrected by turning the adjustment screw. Repeat the task until the desired switch point is reached.
Setting of the reset point
In some applications, the reset point is set rather than the switch point, e.g. for minimum pressure monitoring. Here the task is comparable to the switch point, but without submiting the adjustment screw.
Increase the pressure until the instrument switches.
Then lower the pressure before instrument switches back and adjust the positioning of the adjustment screw accordingly. The rule of thumb here is:
Set point < Actual value: Turn the screw out
Set point > Actual value: Turn the screw in
Setting of the hysteresis (not with all models)
To do this, first set the switch point and then check the reset point (see above). Based on the reset point, the hysteresis screw is turned in or out. The switch point must then be checked, as changes to the hysteresis screw also affect the switch point.
Note
An overview of the many mechanical pressure switches in addition to further technical information can be found on the WIKA website. For those who have any questions, your contact will gladly help you.
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