In a conventional contactor, current flow through the coil creates a _____ to seal in the armature and maintain the contacts in a switched position.

• A. Magnetic Field
• B. Hydraulic Pressure
• C. Electric Voltage
• D. Mechanical Latch

Answer: (A)

Energizing the coil creates a magnetic field in the contactor’s magnetic circuit. This field produces an attractive force on the ferromagnetic armature, pulling it toward the fixed contacts and thereby closing the circuit. That magnetic attraction effectively “seals in” the armature’s position while current flows, keeping the contacts switched. When the current is removed, the magnetic field collapses and springs or inherent mechanical return forces push the armature back to its original position, opening the contacts. The other options don’t fit because hydraulic pressure isn’t involved in a conventional coil-operated contactor, electric voltage is just the cause of current rather than the sustaining mechanism, and a mechanical latch is a separate mechanism not produced by the coil’s magnetic field in a standard setup.