400V 50HZ Motor

[charlie b]

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?

 

[beanland]

Motor Data

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.

 

[Jraef]

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.

 

[charlie b]

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.

 

[Electric-Light]

(5/6)^3 ~ 0.58
60Hz design pump would only operate at 58% power and not provide the design head or flow.

 

[Jraef]

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...

 

[rbalex]

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.

 

[beanland]

Internet

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.

 

[Besoeker]

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/