Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

What materials do I need to wire a VFD?

  1. Dec 8, 2016 #1
    Hi everyone,

    I am part of a senior design group that is building a dynonameter to test shocks. We are ordering parts tomorrow morning and so I want to make sure that I am not missing anything. I do not have any experience with VFD's or three phase motors but I am doing my best to research and learn more each and every day.

    On my parts list I have a three phase motor, a DURApulse GS3-21P0 AC Drive, an input fuse kit for the VFD, a USB to RS-485 adapter (for MODBUS communication), a load-cell, and a temperature sensor.

    My question is: To wire the VFD to the motor what will I need? I assume both the VFD and motor do not come with any wires. I need to connect the VFD to a three phase 50Amp outlet that will be used to power the VFD. My guess would be to order a three phase extension cord off a website like Amazon and then cut off one of the ends off and use the leads to wire to the VFD. Any thoughts? I was thinking perhaps an extension cord like this one; https://www.amazon.com/Conntek-RUL6...d=1481208227&sr=8-2&keywords=250VAC+extension

    **Note: The extension cord in the link above is a 30Amp-250V extension cord. The power supply outlet is a 50Amp outlet. The motor will only draw a few Amps of current. Is it safe to assume that the extension cord provided in the link will be ok for use (provided that prongs are compatible) along with the VFD and the Power supply outlet?

    Thank you!


    The Shock Dyno Control System
    There will be two phases, a warm up phase and a test phase. The warm up phase consists of running the motor until the shock reaches a desired set temperature, when this happens the motor will stop running and there will be a small delay before automatically proceeding to the test phase. Once the test phase starts, the motor will start again and will run until a desired RPM is reached, during the test phase a graph will be plotting force (from load cell) vs RPM.
    Last edited by a moderator: May 8, 2017
  2. jcsd
  3. Dec 8, 2016 #2


    User Avatar
    Gold Member

    Since your load will operate off of single phase at standard outlet current I highly recommend you use a regular outlet. If you wire something wrong on that you will be behind a much smaller safety device and risk is greatly reduced.

    Also that extension is single phase and twist lock connectors are uniquely keyed so the different current ratings will not interchange.

  4. Dec 8, 2016 #3


    User Avatar
    Science Advisor
    Gold Member

    He's ordering a 3-phase motor so he'll need something like this. http://www.rackmountpdu.com/products/970-l21-30-extension-cord-10-foot.aspx

    Edit: well, I guess they do make a single phase input, three phase output model.
    Last edited: Dec 8, 2016
  5. Dec 8, 2016 #4


    User Avatar

    Staff: Mentor

  6. Dec 8, 2016 #5


    User Avatar
    Gold Member

    On a VFD it is prudent to use at least 600V cabling to the motor. Especially on longer runs.

    Like the one the OP has selected.

Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted