What type of action is a contactor described as if it depends on current flow?

• A. Electrically held
• B. Mechanically operated
• C. Manually controlled
• D. Pneumatically activated

Answer: (A)

A contactor that depends on current flow is described as electrically held. This means that its operation relies on electrical energy to maintain its state. When current flows through the coil of the contactor, it generates a magnetic field that attracts the armature, closing the contacts and enabling the circuit. This allows for remote control of large electrical loads without direct human intervention.

The energization of the coil keeps the contacts closed, and if the current flow (and thus the electrical supply to the coil) is interrupted, the magnetic field dissipates, causing the contacts to open and de-energizing the load. This dependence on electrical current is a fundamental characteristic of electrically held contactors, distinguishing them from other types that may operate through different means.

Other options like mechanically operated or manually controlled would not rely solely on electrical current to function, while pneumatically activated would use compressed air rather than electrical flow to operate. Each of these alternatives describes a different operational principle that does not involve the use of electrical current as the primary means of control.