How to Size a Phase Converter

      This discussion of phase converter sizing includes a brief, clear description of how phase converters work. April 21, 2011

Question
I've recently acquired a Weinig p22n 4 head 15hp top, 10hp bottom and 10hp shared for the sides, and 3 hp feed. I am told I need a minimum 30 hp phase converter. Iíve read on here that bigger moulders than mine are run on 20/25hp converters. My machine has an Allen Bradley SMC plus system that evidently allows for a ten second soft start. Can someone please educate me on the converter sizing issue?

Forum Responses
(Solid Wood Machining Forum)
From contributor Z:
I ran this model on a 50 hp phase converter. It had an extra head, and I needed it for the dust collector too, which is another 15 hp. Though it is possible I had more phase converter than I needed. Won't you also need a three phase dust collector on this? You might want the molder on 440 volt to bring the amperage draw down which means adding a transformer.



From the original questioner:
I am wondering how a 70hp 6 head moulder plus or minus the dc could be handled with a 25hp converter. Iíll also be running a 10hp 4 up 4 down collector.


From contributor Z:
You only start one motor at a time on a moulder. So once started, the load is low, and you can keep starting motors. Not sure when it maxes out.


From the original questioner:
Iíve already submitted the machines info and got sizing requirements. 30 hp is recommended. I had a 3 phase Logosol ph260 a year or two ago. This Weinig is my first real moulder. I want to do this right the first time.


From contributor O:
Within some limits one sizes rotary converters to balance the missing phase of the largest motor. In fact all the rotary phase converter is a self switching pair of capacitor banks and another three phase motor that is being used on two windings as a motor and as a generator on the third, which when coupled to the load motor the two motors cross supply each other the missing phase. That is why the converter is sized to the largest motor.

Additional motors, brought on line one at a time, can, with most converters, be added up to three times the rated hp of the converter and all they do is cross feed and support each other. The max load that the converter and its motor ever seeís is the imbalance in the largest motor.



Would you like to add information to this article?
Interested in writing or submitting an article?
Have a question about this article?


Have you reviewed the related Knowledge Base areas below?
  • KnowledgeBase: Knowledge Base

  • KnowledgeBase: Solid Wood Machining

  • KnowledgeBase: Solid Wood Machining: General




    Would you like to add information to this article? ... Click Here

    If you have a question regarding a Knowledge Base article, your best chance at uncovering an answer is to search the entire Knowledge Base for related articles or to post your question at the appropriate WOODWEB Forum. Before posting your message, be sure to
    review our Forum Guidelines.

    Questions entered in the Knowledge Base Article comment form will not generate responses! A list of WOODWEB Forums can be found at WOODWEB's Site Map.

    When you post your question at the Forum, be sure to include references to the Knowledge Base article that inspired your question. The more information you provide with your question, the better your chances are of receiving responses.

    Return to beginning of article.



    Refer a Friend || Read This Important Information || Site Map || Privacy Policy || Site User Agreement

    Letters, questions or comments? E-Mail us and let us know what you think. Be sure to review our Frequently Asked Questions page.

    Contact us to discuss advertising or to report problems with this site.

    To report a problem, send an e-mail to our Webmaster

    Copyright © 1996-2014 - WOODWEB ® Inc.
    All rights reserved. No part of this publication may be reproduced in any manner without permission of the Editor.
    Review WOODWEB's Copyright Policy.

    The editors, writers, and staff at WOODWEB try to promote safe practices. What is safe for one woodworker under certain conditions may not be safe for others in different circumstances. Readers should undertake the use of materials and methods discussed at WOODWEB after considerate evaluation, and at their own risk.

    WOODWEB, Inc.
    335 Bedell Road
    Montrose, PA 18801

    Contact WOODWEB











  • WOODWEB - the leading resource for professional woodworkers


      Home » Knowledge Base » Knowledge Base Article