What type of contacts are Form A contacts?

Form A contacts are classified as normally open contacts. This designation means that in their resting state (when no power is applied), these contacts do not allow current to flow through the circuit—they are open. When an electrical signal or sufficient voltage is applied to the actuating mechanism, these contacts close, allowing current to pass through. This configuration is commonly used in various applications where a circuit should remain open until triggered or activated, making Form A contacts integral to the function of many control devices, such as relays and switches.

The distinction of normally open is critical in understanding how these contacts operate within a system, particularly in control circuits where intentional changes in circuit state are necessary for various operations.