Protection Control Si39-30284 Function4.2 Low Pressure Protection ControlThis low pressure protection control is used to protect compressors against the transientdecrease of low pressure.[In cooling operation] In the case of multi-outdoor-unit system, the entire system performs this control in thefollowing sequence.[In heating operation] In the case of multi-outdoor-unit system, each outdoor unit performs this controlindividually in the following sequence.Low pressure not limitedPe<0.35MPaLow pressure standbyLow pressure limitedAll STD compressorsstop.Master unit:52 Hz + OFF+ OFFSlave unit:StopPe<0.25MPaPe>0.40MPaPe<0.07MPaPe: LP pressure sensor detectionvalue for master unitWhen occurring 3 times within 30 min.,the malfunction code “ E4 ” is output.Pe<0.16 MPaPe<0.13 MPaPe >0.25MPaINV upper limit frequency = 210 HzPe<0.07 MPa&Low pressure not limitedLow pressure standbyLow pressure limited124 Hz + OFF + OFFINV upper limit frequency: 1-step /20 sec up from current compressorfrequency52 Hz + OFF + OFFPe: LP pressure sensor detectionvalue for each outdoor unitPe>0.19 MPaPe<0.16 MPaWhen occurring 3 times within 30 min.,the malfunction code “E4” is output.
