Nothing close enough? Start from a blank circuit diagram → Describe it in one paragraph.
How to use a circuit diagram template.
- 01Add protection devices
Place a circuit breaker or fuse and a thermal overload relay at the top of the control circuit.
- 02Insert contactors and interlock contacts
Drag contactor coils and normally closed auxiliary contacts into the diagram; the auxiliary contacts create the electrical interlock.
- 03Wire the control and power paths
Connect the start/stop buttons, contactor coils, and interlock contacts so only one coil can be energized at a time.
- 04Label components and wires
Assign tags, wire numbers, and a short description to each component for easier troubleshooting.
- 05Export or share the diagram
Download as PNG, SVG, or PDF, or share a live link for review.
Questions about circuit diagram templates
What is a contactor interlock circuit?
A contactor interlock circuit uses normally closed auxiliary contacts from each contactor in series with the opposing contactor's coil. This prevents both contactors from closing at the same time, protecting equipment from short circuits or conflicting operations.
How does electrical interlocking differ from mechanical interlocking?
Electrical interlocking uses auxiliary contacts in the control circuit to block the opposite coil, while mechanical interlocking uses a physical linkage between contactors. Many designs use both for additional safety.
Can I use these diagrams for a dual-pump alternator?
Yes. The dual-pump example shows how two motor starters can be interlocked so that only one pump runs at a time, or they alternate based on control logic.
What is a mains-generator changeover interlock?
It ensures the main supply contactor and the generator contactor cannot both be closed, preventing back-feeding and possible damage. The interlock forces one contactor to open before the other closes.
Do these diagrams include star-delta starting?
Yes. The star-delta example includes interlocked main, star, and delta contactors so that the star and delta contactors never close simultaneously during the transition.