Relay Contact Types Demystified: NO, NC, and Changeover Functions > 자유게시판

When working with relays, comprehending the different contact types is essential for designing reliable electrical circuits. The main relay contact types are open-by-default contacts, normally closed (NC), and SPDT, each designed for specific operational needs. Picking the correct contact depends on the specific logic required upon energization.

A NO contact is open by default when the relay is de-energized, meaning the path is interrupted. When the coil is energized, the contact closes, enabling power transmission. This setup is well-suited for use cases where a device should operate exclusively during activation, such as starting a motor via an external trigger.

A closed contact operates in the inverse logic. It is in a connected state when the relay is not powered, انواع رله maintaining power delivery. When power is applied to the coil, the contact disconnects, shutting down the load. This configuration is ideal for emergency shutdown circuits, where the system defaults to active mode, such as a safety interlock.

transfer contacts merge two contact states into a single pole. They feature a common terminal that connects to either the NC or NO terminal. When off, the common terminal is connected to the closed path. When activated, it transfers to the alternative circuit. This makes changeover relays excellent for applications requiring seamless switching between two power sources, such as switching from main to backup power.

Assessing your circuit requirements—whether you need to engage a load, deactivate it, or change circuit routing—will help you choose the right relay. Always consult the relay’s manufacturer documentation to validate the contact type and verify load capacity, guaranteeing proper functionality. Selecting the correct contact setup not only ensures proper functionality but also reduces failure risk.