×
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

Star - Delta with two motors

Star - Delta with two motors

Star - Delta with two motors

(OP)
My Problem is this: I have two 150kw 3ph motors sharing a multi belt rotor, i need to wire this so that one motor starts in star which means the other motor is turning with it at the same speed then when the delta contactor/s kick in BOTH motors will be powered in delta, do i achieve this with one star contactor and two delta contactors? or just up the size of the whole star delta set of contactors to take the fla of both motors in delta and wire the delta side of both motors to the delta contactor?



 

RE: Star - Delta with two motors

(OP)
I guess nobody has an answer?

RE: Star - Delta with two motors

In general, Star-Delta starting is risky at best to use on one motor. Doing what you intend is something I would never think of; the risks are not worth the benefits.

But if you insist, you cannot run 2 motors from one starter circuit anyway, unless you have separate sort circuit and overload protection devices anyway. In that case, what are you saving here by trying to use only one larger contactor? You would still need to have another SCPD and OL downstream in that case. Nothing saved.

If you insist on using Star-Delta, just start motor #1 with it, and then have a separate DOL starter for motor #2, closing that contactor only after the Delta contactor is closed. I would use a soft starter and start them both behind the soft starter, with separate MCCBs and Overload Relays downstream. In the IEC world (assuming you are there because you used kW instread of HP), you can likely get an MCCB with an adjustable thermal OL built-in.

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