The Electrical Contractor Network

ECN Electrical Forum
Discussion Forums for Electricians, Inspectors and Related Professionals

Books, Tools and Test Equipment for Electrical and Construction Trades

Register Now!

Register Now!

We want your input!

Featured:
   

2017 NEC and Related
2017 NEC
Now Available!

   
Recent Posts
Calling all Non-US members!! (Non-US only)
by aussie240
Today at 02:39 AM
Photo Upload Tutorial
by DanK
Yesterday at 11:35 PM
Sprinklered equipment 26-008
by bigpapa
12/02/16 04:24 PM
On Delay Relay with Auto Reset
by Potseal
12/01/16 09:59 AM
Wow, that was close!
by jraef
11/28/16 07:06 PM
New in the Gallery:
12.5A through 0.75mm˛ flex (just out of curiosity)
Shout Box

Top Posters (30 Days)
gfretwell 13
HotLine1 9
Texas_Ranger 8
sparkyinak 7
Trumpy 6
Who's Online
0 registered (), 282 Guests and 4 Spiders online.
Key: Admin, Global Mod, Mod
Topic Options
Rate This Topic
#193952 - 04/30/10 10:03 PM Wye Delta Start Closed Transition
DYNAMITE Offline
Member

Registered: 12/22/03
Posts: 37
Loc: Winkler, MB, Canada
Would anyone know how to size the resistors on a Wye start/delta run closed transition starter? Say for a 50 Hp 230V motor?

Top
#194021 - 05/05/10 01:48 AM Re: Wye Delta Start Closed Transition [Re: DYNAMITE]
Scott35 Offline

Broom Pusher and
Member

Registered: 10/19/00
Posts: 2724
Loc: Anaheim, CA. USA
I believe the Resistors would be sized ("size" = Resistance value - in Ohms), so as to allow the same level of Current that the "Wye" configuration does.

Example:
Motor's FLA = 130 Amps
Starting (Wye Connection) Ampere = +/- 75 Amps
Resistors are sized to allow +/- 75 Amps at rated Voltage.

I am not 100% sure on this, so let me find some references, then reply back.

Scott
_________________________
Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!

Top
#194026 - 05/05/10 08:54 AM Re: Wye Delta Start Closed Transition [Re: Scott35]
DYNAMITE Offline
Member

Registered: 12/22/03
Posts: 37
Loc: Winkler, MB, Canada
That makes sense to me. The smaller you make them the closer to normal current you have. The next question is Watt ratings. The resistors are only in the circuit for a split second in the transition between wye and delta so would you need full power ratings(Peak I^2 R) on them?

Top



ECN Electrical Forums - sponsored by Electrical Contractor Network - Electrical and Code Related Discussion for Electrical Contractors, Electricians, Inspectors, Instructors, Engineers and other related Professionals