Product guide
Cam and Changeover Switches: Read the Contact Schedule
Understand cam-switch positions, contact schedules and switching duty before selecting a rotary control or changeover device.
In this article
A cam switch uses shaped cams on a rotary shaft to operate groups of contacts. The contact schedule defines which terminals connect at each position; the handle legend alone does not fully describe the circuit.
Start with the switching sequence.
For a position marked 1–0–2, identify exactly what is connected in positions 1 and 2 and whether every required path is open in position 0. Check the transition between positions as well as the stable positions.
Break-before-make and make-before-break sequences serve different applications. Do not select one without checking the circuit. Source changeover must prevent unintended interconnection of supplies using a device and arrangement designed for that purpose.
Different tasks need different schedules.
- Control selection: route the required signals at each position.
- Meter selection: use a circuit designed for the specific instrument and measurement arrangement.
- Motor control: confirm the contact sequence and rated duty for the motor application.
- Changeover: verify poles, transition behaviour and source-isolation requirements.
What to supply with an enquiry.
Provide a position-by-position connection table or schematic, operating voltage, load type and current. Include the required handle positions, return action if any, panel dimensions and mounting arrangement.
Two rotary switches with the same number of positions can have different internal connections. Compare the full diagram before replacing a device. Browse Jinhong cam switches and request the exact contact schedule for the proposed model.
Prepare a cam-switch contact schedule
For each required handle position, record the connections the circuit needs. Add the transition requirements separately, since stable-position labels do not describe the change between positions.
| Check | Information to record |
|---|---|
| Stable positions | List each position and the terminal pairs that must be connected. |
| Transition | Specify the required break-before-make or make-before-break behaviour. |
| Rated duty | State voltage, load type, current and the intended switching task. |
Are two 1–0–2 switches electrically interchangeable?
Not necessarily. The same handle markings can accompany different contact schedules. Compare the complete connection table and switching duty.
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Catalogue examples from the ranges discussed. Open a model to check its configuration and technical details.
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