ANALYSIS .

The image attached to this write up is a basic compressor electrical control .The control is a simple two rungs ladder logic control circuit. Recall that our objective was to :
"to start our compressor motor "IF compressor stored pressure is BELOW allowed pressure limit and switch it OFF "IF" compressor accumulated pressure is ABOVE set limit" .Our primary objective therefore is to develop an equivalent logic circuit for the statement highlighted in yellow .
Legend :
XCB = Miniature CB
XOFF = Stop switch
XStart = Start Switch
YC1 = NO contact of YC1 contactor.
YC1 =Main Contactor Coil
XPR_SW. = pressure switch.
XOL = Overload relay
YR1 = Recycle relay
YR1 = Recycle relay contact
YC1. = contactor auxiliary
contact. See ladder logic circuit.