Page 2 of 2 FirstFirst 12
Results 11 to 18 of 18

Thread: Phase Converters - 240/1 to 208/3

  1. #11
    Join Date
    Sep 2008
    Location
    UK
    Posts
    10,361
    Quote Originally Posted by MAC702 View Post
    A typical 10-ton HVAC package or condensing unit would need about 12 kVA.

    Now, he says these are split systems, so in addition to the condensing units, we have three air handlers that also need power. A 10-ton air handler will probably be 3-phase equipment as well, about 2 kVA each.

    Air handlers might complicated the matter greatly because whereas condensers are often located near one another and fed from the same panel, it is quite common that air handlers will be close to the space they condition, and are often fed from their nearest panel.
    Thank you for the information, sir.
    Si hoc legere scis nimium eruditionis habes.

  2. #12
    Join Date
    Dec 2007
    Location
    NE Nebraska
    Posts
    33,757
    Do the units have basic across the line started compressors?

    Air handlers very well may be single phase even though the compressors are three phase.

    Why will it take so long to get three phase service if there is already three phase primary on the pole?

    Is the existing single phase transformer large enough to handle the load? If not you may have to wait for POCO regardless.

  3. #13
    Join Date
    Dec 2007
    Location
    Dayton, OH
    Posts
    131
    ...re Why will it take so long...? Dunno. It's PG&E. In San Francisco.

    The Existing service is 400A at 240/1. We are looking at ways of reducing some of our load. Like using only One of the splits (temporarily sharing ducts) if we can do it during a temperate season.

  4. #14
    Join Date
    Jul 2017
    Location
    Western Grove, AR Newton County
    Posts
    28

    Phase Converters - 240/1 to 208/3

    This is going to get pricey real fast. Rotary Phase converters have come a long way in the last ten years. Having a 240 1P feed and a 208 3P need complicates things. Lots of the Rotary Phase Converters are listed in Horsepower not in VA, Amps, Watts, etc but usually have a Badge Plate with HP and Amperage Info. The Horsepower is typically the rating of the Motor being used as a rotating Transformer to come up with the missing phase. So a 60 Horsepower range is close to what you are after for a 50 Amp need but I believe you will have an issue with obtaining 208 Volts; it will most likely be 240 3P.
    I would suggest looking at some of the YouTube videos to come up with some of the better Builders / Manufacturers and contact them for the ability to purchase a System that will take the incoming power and deliver a different base output. Worst case would be to temporarily install a Transformer to drop it down to 208 3P in the proper configuration so everything you are expecting from the final POCO drop exists now.
    If the Refrigeration Compressors can operate on 240 3P, you pretty much have it made with Rotary Phase Converters. You will need to compare the economics of 1 large Rotary Phase converter versus one for each of the Refrigeration Compressor units.
    JimO

  5. #15
    Join Date
    Jul 2007
    Location
    Clark County, NV
    Posts
    636
    Quote Originally Posted by jimo144 View Post
    ...If the Refrigeration Compressors can operate on 240 3P...
    Don't know what equipment he's getting, but 10-ton condensers are definitely out there that operate on both 208 and 230 (240) nominal 3Ø voltages. Perhaps even most of them.

  6. #16
    Join Date
    Dec 2007
    Location
    NE Nebraska
    Posts
    33,757
    Quote Originally Posted by MAC702 View Post
    Don't know what equipment he's getting, but 10-ton condensers are definitely out there that operate on both 208 and 230 (240) nominal 3Ø voltages. Perhaps even most of them.
    So are 10 ton units with two 5 ton single phase compressors in them, and may be the less cost route then going with phase converters.

  7. #17
    Join Date
    Feb 2013
    Location
    India
    Posts
    2,215
    Quote Originally Posted by kwired View Post
    So are 10 ton units with two 5 ton single phase compressors in them, and may be the less cost route then going with phase converters.
    Also some manufacturers may void their equipment warranty if operated with phase converters.

  8. #18
    Join Date
    Dec 2007
    Location
    NE Nebraska
    Posts
    33,757
    Quote Originally Posted by Sahib View Post
    Also some manufacturers may void their equipment warranty if operated with phase converters.
    True, my ecxperiences with rotary or static phase converters is there is unbalanced current in motor input leads, this is a crude way to make a phase angle between input leads to create rotation, but is far from perfect 120 degrees you see with true three phase source, if motors are not oversized for the driven load they don't last as long as they will on a true three phase source. Most applications I run into are fairly intermittent in nature or if continuous duty the motor is intentionally oversized from what it would be on a true three phase source.

    You won't find a HVAC compressor intentionally oversized in such a manner. If anything an inverter type phase converter or VFD would be the best conversion equipment for this application I would think.

    Less energy efficient and probably more expensive would be a motor driving a generator, might be easier to sell when you don't need it anymore though.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •