×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

60->50Hz Frequency Converter with Regenerative Loads

60->50Hz Frequency Converter with Regenerative Loads

60->50Hz Frequency Converter with Regenerative Loads

(OP)
We have an application that requires the use of a frequency converter 480V/60Hz mains, 400V/50Hz loads. The 50Hz side must be a low distortion sine wave so a rotary phase converter is being considered.

(Scenario 1) On the 400V/50Hz load side we will have:
1) A constant 3-phase load of 10KW
2) A 10KW 3-phase device that can regenerate AC.

During regeneration, the power generated will be consumed by the constant 10KW 3-phase load and the loading of the frequency converter drops and all is well.

(Scenario 2) On the 400V/50Hz load side we will have:
1) A constant 3-phase load of 10KW
2) A 10KW single-phase device that can regenerate AC.

During regeneration we will have 10KW flowing back on a single phase pair (10KW/400V = 25A). The 3-phase load will consume 10KW 3-phase = 14.4A per phase leaving 10.6A of current flowing back towards the frequency converter on a single phase pair.

From what I have been able to find so far, most frequency converters do not like current flowing back into them as the voltage may rise causing a shut down. One solution is to load down the single phase pair so that the frequency converter always sees a load even during regeneration. To keep the distortion low a resistive load bank could be used. Burning off the excess power as heat is not desirable in this application.

Questions:
1) Does anyone know of a phase converter that can handle these two scenarios without faulting or going out of control?
2) Since it is only a single phase pair that current would be flowing backwards on, would this current be used by the phase converter to provide a portion of the shaft torque and still remain under control?

Thanks in advance for any thoughts on this.

Bill

RE: 60->50Hz Frequency Converter with Regenerative Loads

You can use a transformer to mitigate this somewhat.
Delta primary and zig-zag or double delta secondary.
aif the single phase load is connected on C phase, then "C" phase will supply 1/2 of the current and "A" phase and "B" phases, acting as an open delta with a load across the open side will supply 1/2 of the current. The phase angles of the currents will be such that "A" phase will see 2.5 kW and 5 KVA and phase "B" will see 2.5 kW and 5 KVA.
But, if the rotary phase converter is using a delta winding it may do this itself without the aid of a transformer.

Bill
--------------------
"Why not the best?"
Jimmy Carter

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources