Which wires are the control wires?

Which wires are the control wires?

• A. 2E and 4E Post
• B. 1E and 2E Post
• C. 1E and 3E Post
• D. 3E and 1E Post

Answer: (D)

Control wires carry the signals that energize relays or coils to operate the signal post. They form the control loop and are distinct from the main power or track-circuit wires. In the diagram, the wires labeled with E and ending in Post are parts of the control path to the post relays. The pair that actually forms the control circuit for energizing the post coils is 3E Post and 1E Post, because these two wires directly feed the control coils at the post when a control signal is applied. The other wires labeled 2E Post or 4E Post serve other parts of the system (such as different devices or non-coil circuits) and do not constitute the coil energizing control path.

Control wires carry the signals that energize relays or coils to operate the signal post. They form the control loop and are distinct from the main power or track-circuit wires. In the diagram, the wires labeled with E and ending in Post are parts of the control path to the post relays. The pair that actually forms the control circuit for energizing the post coils is 3E Post and 1E Post, because these two wires directly feed the control coils at the post when a control signal is applied. The other wires labeled 2E Post or 4E Post serve other parts of the system (such as different devices or non-coil circuits) and do not constitute the coil energizing control path.