Compressor does not stop

!Screw compressors do not stop and restart like piston compressors.

/d series compressors

Those compressors are VSD/ VFD inverter drive compressors. /d series compressors will adjust the air flow (CFM) of the compressor according to air demand by monitoring and keeping the pressure on the outlet of the compressor constant or within a small bandwidth. /d compressors has internal off loading timer. When compressor goes into min frequency and stays at min frequency for a period of offloading time compressor will go into sleep mode. If there is a slight change in frequency due to a very small pressure drop measured at the compressor outlet, off loading timer will be reset and start counting down from the time off loading timer set whenever compressor frequency goes back to min. frequency it is designed for.

The exception to this rule is when compressor is in heating function.

If the Compressor element temperature (shown on the Compressor display in C) below 158F (70C) and the air demand is not enough to keep the Compressor run under load to heat the Compressor internally, discharge valve will dump some air to maintain maximum flow to heat the compressor quickly to avoid condensation. Such discharge action on the solenoid valve may be a cycling action. That is completely normal and varies according to tank(s), tubing in the compressed air system and compressed air usage. Till compressor reaches to min required temperature, it will not count down the off load timer and will not stop.

*Time to reach to min. required temperature by the compressor may considerably increased as ambient temperature goes lower.

/x series compressors

/x series screw compressors must ensure min. time run before they stop according to the size of the main motor. Electric motors may only be start and stop so many time in an hour and 24 hour period to avoid heat accumulation on the motor if they start with in rush current demanding starting methods. In order to avoid the excess heat accumulation on the electric motor, there is an off load timer built in the compressors which makes sure compressor runs enough time at off load period so that motor will be cooled down when it is running.

!Tampering or changing the off load timer or heating function levels without the written consent of Us Air Compressor may void the warranty and cause irreparable damages on the compressor or the parts in it.