The door seal get air through the electric solenoid valve VEPPO that is normally open. That valve must be energized to get it to close and stop supplying air to the door seal and let it deflate. VEPPO energizes one of two ways. Either relay contact CRD or CLA must close. CRD energizes when the door open button is pushed. This closes the contact CRD at line 03. As soon as someone releases the door open button, CRD deenergizes and the relay contact CRD opens. Relay contact CLA closes when the door is open (not closed). CLA energizes closing the CLA contact. Since this is a latching contact, when you close the door and the relay coil CLA is no longer energized, the contact CLA at line 04 is still closed keeping the seal deflated. The only way to open the CLA contact is by resetting CLA. The reset coil for CLA (line 02) gets power from the EV page at line 6 through diamond G. Diamond G gets power when the drain valve is commanded to close. This is the first thing that happens at the start of a formula. CLA resets, and CLA contact opens allowing VEPPO to deenergize and open. Then the door seal inflates.


CSH 05-10-13