Which code is the Switch control relay?

• A. Vc
• B. Wz
• C. Wg
• D. Wpbx

Answer: (B)

Relay coding in railway signaling uses lettered designations to show a relay’s function. For switch operations, relays are grouped under a prefix that signals turnout control, and the following character names the particular device within that group. The switch control relay is designated by the code Wz, which is how technicians identify the relay that handles turnout actuation in the interlocking circuit. When you inspect a schematic or equipment list, a Wz relay will be the one tied to the switch mechanism and its control logic, confirming its role. Other codes belong to different relay groups or purposes and do not represent the switch control relay.