In a signaling system, when a normally open contact energizes, what is the resulting state?

In a signaling system, when a normally open contact energizes, what is the resulting state?

• A. It remains open
• B. It closes
• C. It becomes fused
• D. It detects train occupancy

Answer: (B)

A normally open contact closes when energised. In its idle state, the contact is open so no current can flow. Energising the coil pulls the contacts together, completing the circuit and allowing current to pass to the next device (for example, signaling the indication or interlocking). It does not stay open when energised, it doesn’t fuse as part of normal operation, and occupancy detection is not a property of the contact state itself—detection is handled by separate sensing elements, while the contact state simply indicates whether the circuit is completed.

A normally open contact closes when energised. In its idle state, the contact is open so no current can flow. Energising the coil pulls the contacts together, completing the circuit and allowing current to pass to the next device (for example, signaling the indication or interlocking). It does not stay open when energised, it doesn’t fuse as part of normal operation, and occupancy detection is not a property of the contact state itself—detection is handled by separate sensing elements, while the contact state simply indicates whether the circuit is completed.