The anti-pump relay is a C-contact relay that has Ya and Yb contacts, which operate in opposite directions (one opens while the other closes). For example, when the LS3 (3–4) contact closes, the anti-pump relay is energized, causing the Ya contact to close and the Yb contact to open, as shown in the figure above. The Ya contact energizes the relay, and the relay keeps the Ya contact closed, allowing the relay to maintain the energized condition. If the breaker needs to be closed (“ON”) again, the A3–A4 circuit should be re-energized to make the Yb contact closed and allow the breaker to close.

When either 52b is open (which indicates the breaker open/close status) or Yb is open, additional power is prevented from reaching the CC. This prevents repeated or continuous energization of the closing coil, thereby protecting it from overheating or damage.