How to change 'Star-Delta starter panel' to run a 'Part wind start motor'?

‘Star-Delta starter panel’ to run a ‘Part wind start motor’

Star - Delta to Part-wind Alteration of Starter Control set up Many older range compressors were originally supplied as Star Delta, but current supply is mostly for Part wind start type motors. It is a simple alteration to modify an existing Star - Delta starter panel to correctly operate a Part wind start motor. Important Note It is not possible to convert a Part wind panel to Star Delta without considerable modification. 1 Connect power leads from Main contactor to terminals 1 - 2 - 3 (upper 3 pins). Note the order of the incoming phases e.g. Red - 1; Yellow - 2; Blue - 3. 2 Connect the power leads from the Delta contactor to terminals 7 - 8 - 9. Note the same originating phase to 7 must be same as 1, 8 as 2, & 9 as 3, e.g. Red - 7; Yellow - 8; Blue - 9. This is most important as it is vital both partwinds rotate in the same direction. NB on Copeland compressors generally the terminal markings for EWM (Star Delta) & AWM / FWM / FSM (partwind) should be unaffected by this alteration in regard to actual connections. On Copeland AWM it is vital the 1st partwind (Main) contactor operates upon the upper set of terminals (1 - 2 - 3)(larger partwind). 3 Disconnect & remove entirely the star contactor. However if auxiliary controls are wired to the star contactor, e.g. Start unloader, delay time, etc. then the star contactor may be left in place, however IT IS VITAL TO REMOVE & DISCARD THE STAR CONTACTOR LINKS, otherwise the 2nd partwind will effectively become shorted out during start up and this could lead to damage due to induced current (transformer effect) whilst the 1st partwind operates. 4 If an adjustable timer is utilised on the existing star delta changeover then adjust this to give approximately 0.75 secs. If a fixed timer is used no detriment will occur if the delay is up to 1.5 secs, however if a longer delay was previously used then a suitable shorter delay time should be installed. Testing Upon first start of the compressor the 1st contactor will close, with the disconnected star contactor if still installed. After the delay period the star will open and the 2nd part wind contactor will close. At this point be ready to cut power if the motor stalls, however, if no noticeable change in motor note is heard then simply check amps are balanced on each part wind. Q. What are correct settings on a R407c (gas) chillers & systems? Superheat settings on R407c Chillers & Systems At typical suction pressures on chilled applications i.e. 60 - 80 psi, R407c has a glide range of about 5oK. In order to ensure the refrigerant gas is properly superheated across the entire glide range of the refrigerant, and bearing in mind at minimum superheat of any component must be at least 5oK above the saturation temperature to ensure liquid refrigerant is not returning to the compressor, the superheat control of the TEVv must be properly set. Also there is also a lot of opinion as to how best set / check the TEVv settings for systems using high glide gases such as R407c. Basic advice for TEVv settings should be set at superheat of 5 - 7oK on the Bubble temperature or 10 - 12oK on the Dew temperature Differential Leakage Blended refrigerants are prone to a phenomenon of Differential Leakage. Due to variations in molecular size certain base gases may leak through smaller holes than other heavier gases used in the blend. Once leakage has occurred it is not possible to ascertain the change to the original blend any whether the resultant gas remains within the band of tolerance laid down by the makers. Thus in any system where leakage has occurred above 15% of the plated weight then differential leakage may have upset the balance of the blend of gases, resulting in a variation from the intended design of the refrigerant to something unknown. Thus the entire gas charge must be disposed of and new gas used. The secondary problems this can cause are not yet fully documented, but as a rule the above advice should avoid undue trouble. Any ??? on this subject please refer to me for discussion, although we are still very much on the learning curve for this gas.