The device that prevents two opposite functioning relays from closing at the same time is called a _______.

The device that prevents two opposite functioning relays from closing at the same time is called a _______.

• A. electrical interlock
• B. mechanical interlock
• C. purity interlock
• D. safety interlock

Answer: (B)

A mechanical interlock is used to keep two opposing relays from both closing at once by using a physical linkage or blocking mechanism. When one relay is energized, the interlock geometry moves a part that prevents the other relay’s contacts from closing, and often vice versa. This guarantees that only one path can be energized, which is crucial in circuits like forward/reverse motor starters to avoid short circuits or mechanical clashes. The other terms don’t fit because an electrical interlock relies on wiring and control logic rather than a physical device, a safety interlock typically protects people or equipment rather than coordinating relay action, and a purity interlock isn’t a standard term in this context.

A mechanical interlock is used to keep two opposing relays from both closing at once by using a physical linkage or blocking mechanism. When one relay is energized, the interlock geometry moves a part that prevents the other relay’s contacts from closing, and often vice versa. This guarantees that only one path can be energized, which is crucial in circuits like forward/reverse motor starters to avoid short circuits or mechanical clashes. The other terms don’t fit because an electrical interlock relies on wiring and control logic rather than a physical device, a safety interlock typically protects people or equipment rather than coordinating relay action, and a purity interlock isn’t a standard term in this context.