Results 1 to 9 of 9

Thread: 400V 50HZ Motor

  1. #1
    Join Date
    Feb 2003
    Location
    Seattle, WA
    Posts
    17,245

    400V 50HZ Motor

    I have an overseas project that involves a 10 HP motor (fire pump) on a three phase, 400 volt, 50 hertz system. I am sizing the conductors and OCPD. Table 430.250 does not cover this voltage level. Article 406.1(A) does not give me the freedom to interpolate the tabulated values, but absent any other resolution, that is what I will do. I don’t have access to the motor yet, so I can’t go by the nameplate. Anyone have an information source I can tap?
    Charles E. Beck, P.E., Seattle
    Comments based on 2014 NEC unless otherwise noted.

  2. #2
    Join Date
    Sep 2004
    Location
    Vancouver, WA
    Posts
    660

    Motor Data

    I suggest you use the Internet to locate data for a 10Hp (7.5kW?) 400V 50Hz 3-phase motor. ABB might be a good starting point.
    e^(i pi) = -1

  3. #3
    Join Date
    Jul 2006
    Location
    San Francisco, CA, USA
    Posts
    3,896
    Just curious, why would you be concerned with the US NEC on a project overseas? That's why the NEC doesn't address voltages found in other countries by the way. I would think it a better idea to find out what standards are used in the destination country and go by that. For example a lot of counties use British Standards for things like this, especially former British colonies like India, Pakistan and several mid-east countries.

    You might see if your library has a copy of this book, "World Industrial Standards Speedy Finder". I've found it at a local University library, pretty useful for things like this. It cross references US standards to applicable standards in other countries.


    Barring all that, if you are supplying from here based on a 460V 60Hz motor, when using it at 400V 50Hz, the current is not going to be much different because the motor is going to spin 20% slower at 50Hz. So the pump will be doing at least 20% less work and if it's a centrifugal, it will be doing only 64% of the work it would do at 60Hz. I would thing if you sized the conductors based on 460/60, they will be over sized for the new application. So the only other concern is the SCPD for the motor windings, and being that Fire Pumps are "run to destruction" anyway, I don't see a concern if based on the 460/60 values.
    Last edited by Jraef; 05-06-11 at 12:35 PM. Reason: Spelling... arghhhh!
    __________________________________________________ ____________________________
    "Dear future generations: Please accept our apologies. We were rolling drunk on petroleum."
    — Kilgore Trout (via Kurt Vonnegut)

  4. #4
    Join Date
    Feb 2003
    Location
    Seattle, WA
    Posts
    17,245
    This is a US-controlled facility on foreign soil. Project design requirements include the application of US codes to the extent possible.

    The FLA of a 10 HP motor is 14 amps at 460 volts and 28 amps at 230 volts. Interpolation gives me just under 18 anps at 400 volts. I will use 20 amps for calculation purposes.

    Thanks for the input.
    Charles E. Beck, P.E., Seattle
    Comments based on 2014 NEC unless otherwise noted.

  5. #5
    (5/6)^3 ~ 0.58
    60Hz design pump would only operate at 58% power and not provide the design head or flow.
    Last edited by Electric-Light; 05-06-11 at 03:33 PM.

  6. #6
    Join Date
    Jul 2006
    Location
    San Francisco, CA, USA
    Posts
    3,896
    Quote Originally Posted by charlie b View Post
    The FLA of a 10 HP motor is 14 amps at 460 volts and 28 amps at 230 volts. Interpolation gives me just under 18 anps at 400 volts. I will use 20 amps for calculation purposes.
    Oh duh! I don't know what I was thinking, seems so obvious now... I guess was thinking motor power issues, sometimes I get on a track and can't get off of it. I've been dealing with a lot of 50Hz motor issues lately on equipment coming into the US from other countries. Now that we don't make machinery in this country any longer this seems to be consuming my life lately...
    __________________________________________________ ____________________________
    "Dear future generations: Please accept our apologies. We were rolling drunk on petroleum."
    — Kilgore Trout (via Kurt Vonnegut)

  7. #7
    Join Date
    Apr 2004
    Location
    Mission Viejo, CA
    Posts
    4,108
    I don’t know the exact location of your project, but it’s possible that the motor is rated 380V on a system nominal 400V. That will “up” your interpolation a bit, but 20A is still probably good – remember Tables 250.247 to 250 are based on the absolute worst motor any NEMA manufacture makes.
    "Bob"
    Robert B. Alexander, P.E.
    "I know that you believe you understand what you think the NEC says, but I am not sure you realize that what you read is not what it means." (Corollary to Charlie's Rule)

  8. #8
    Join Date
    Sep 2004
    Location
    Vancouver, WA
    Posts
    660

    Exclamation Internet

    5 minutes of Internet searching:

    Marelli 132 Frame - 7.5kW 3ph 2 Pole AC Motor for 400V or 660V 3 phase supply. Use with 400V Variable Frequency Drives or a fixed frequency mains supply at 50Hz.

    Can be used over a 10:1 Speed Control range from 290RPM to 2910RPM, with suitable de-rating at the lower speeds.

    Fixed mains supply output is 7.5kW (10HP) x 2910RPM at 400V x 50Hz 3ph.

    Full Load Current - 14.8A at 400V.
    Overload - 150% x 60seconds.
    Power Factor is 0.84 when mains connected at 50Hz.
    Set terminal box links 'three a-breast' for 400V 'Delta' connection.
    Set terminal box links ‘two at one side’ for 660V 'Star' connection.

    252mm Wide x 482mm Long x 316mm high overall in its IP55 enclosure.
    Foot mount on 11mm holes at 216mm wide x 140mm centres 89mm back from shaft shoulder.
    Shaft side load is 177kg for 20,000hrs life
    Weight is 45kg.

    Rated at 40C Ambient.
    Ventilation space required at rear cooling air intake.
    e^(i pi) = -1

  9. #9
    Join Date
    Sep 2008
    Location
    UK
    Posts
    6,560
    Quote Originally Posted by charlie b View Post
    I have an overseas project that involves a 10 HP motor (fire pump) on a three phase, 400 volt, 50 hertz system. I am sizing the conductors and OCPD. Table 430.250 does not cover this voltage level. Article 406.1(A) does not give me the freedom to interpolate the tabulated values, but absent any other resolution, that is what I will do. I don’t have access to the motor yet, so I can’t go by the nameplate. Anyone have an information source I can tap?
    About 14.5A per my computer model I generally use and 15A from a table of typical motor currents in a distributors catalogue (Europa Components).

    http://www.europacomponents.com/

Posting Permissions

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