A microswitch transfers a common contact between normally closed and normally open contacts through snap action. Compare actuator position with operating-position limits and movement differential from the switch data sheet.
Microswitch Position-Band Calculator
Enter the data-sheet operating-position limits, maximum movement differential and applied actuator position. The worksheet identifies guaranteed outer regions and the history-dependent band; it does not predict electrical ratings, bounce or service life.
Equation Used
- All positions share the same datum and increasing direction.
- OP limits and MD maximum come from the exact switch/actuator data sheet.
- The comparison is quasi-static; acceleration, actuator compliance and impact are excluded.
- Contact form, electrical load, bounce, life, environment and functional safety are excluded.
Operating-position limits and movement differential define the position range where contact state may depend on the unit and its direction of travel.
Snap action and three-terminal contact form
A basic snap-action switch stores elastic energy as its actuator moves, then rapidly transfers the common contact between the normally closed and normally open contacts. Manufacturer terminology separates operating position, release position, pretravel, overtravel and movement differential.
The animation shows COM, NC and NO schematically. It does not infer the internal spring geometry or electrical state of a specific part from force alone.
A declared position-band worksheet
Use the worksheet to translate exact data-sheet OP limits and MD maximum into a common installation datum. It does not select a switch, define a safety function or determine electrical compatibility.
Position and differential bounds
With only MDmax known, OPmin-MDmax is the earliest bounded release position. Between that bound and OPmax, state may depend on the actual unit and direction of travel.
Declared-band example
For OP limits 8.2 to 8.8 mm and MDmax 0.2 mm, OP span is 0.6 mm and the earliest bounded release position is 8.0 mm. At 9.0 mm the actuator is 0.2 mm above OPmax.
Position limits and electrical behavior
Manufacturer data show that force, travel, position, contact ratings and endurance are product- and actuator-specific. Debounce belongs to the complete electrical system and measured signal behavior.
Microswitch position questions
Does the history band mean the switch is defective?
No. Snap switches intentionally have movement differential between operation and release.
Does being above OPmax prove electrical suitability?
No. It is only a geometric position comparison.
Does this calculate debounce?
No. Contact bounce and filtering require the exact switch, load, circuit and measured waveform.
Manufacturer references
- Omron, Technical Explanation for Basic Switches: definitions for OP, RP, MD, force and travel characteristics.
- Omron, Basic Switch force-stroke explanation: snap action, operating/releasing positions and movement differential.
- Honeywell ZM/ZM1 data sheet: product-specific OP, PT, OT and DT values.
- Panasonic, Microswitch Terminology: operating characteristics and position/travel definitions.
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