ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
ShoutChat
Recent Posts
May I backfeed 3 phase transformer?
by dsk - 10/22/21 04:37 AM
Wire sizing
by gfretwell - 10/21/21 10:12 PM
GFCI's pops in large numbers
by dsk - 10/21/21 02:03 AM
Need some info on Japanese outlets, 200V 15A
by andey - 10/20/21 08:05 AM
nec 110.3 (B)
by watersparkfalls - 10/19/21 07:09 AM
New in the Gallery:
240/208 to a house
240/208 to a house
by wa2ise, October 9
Now you know.
Now you know.
by Tom_Horne, September 7
Who's Online Now
0 members (), 13 guests, and 18 robots.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Page 1 of 2 1 2
#181582 10/16/08 09:23 PM
Joined: Apr 2003
Posts: 362
Member
Hi Guys, I need some help with calculating size of phase converter, Line, load overcurrent. The Ice cream maker I am working this up for is 208/240v 30a I don't have access to the motor. It would require dismantling the unit. Any help would be apprciated.


Ob(Phil)


Choose your customers, don't let them choose you.
Joined: Jun 2007
Posts: 301
J
Member
Phil,
Are you trying to get 3 phase,or are you trying to change Hz?

JValdes #181597 10/17/08 10:25 PM
Joined: Apr 2003
Posts: 362
Member
Trying to get 3 phase.


Choose your customers, don't let them choose you.
Joined: Jan 2005
Posts: 5,316
Cat Servant
Member
The easiest, best way is with a decent VFD .... it will convert single phase to true three phase.

Joined: Jun 2007
Posts: 301
J
Member
The VFD will work fine on the motor, but the controls could be damaged.
If all you need the 3 phase for is the motor, give me the motor name plate information. Specifically HP, voltage and current. Or you can go to www.kbelectronics.com. Here look for the inexpensive chassis type control. The dimensions will be approximately 4"x4"x2" for controls under 5 HP.

Note: The output of a VFD is not a true sign wave. It is a simulated sign wave derived from the DC bus on board the drive. This output is not as clean as a true sign wave like you would see with a transformer output. That is why you must use caution using motors that are not designed to be used on VFD's. Motors that are VFD rated have magnet wire that is rated for over 1500 volts and in some cases special bearings. Do not let this over concern you. It is just a warning of possible motor failure.

Last edited by JValdes; 10/18/08 12:04 PM.
JValdes #181610 10/19/08 10:08 PM
Joined: Apr 2003
Posts: 362
Member
Unfortunatly, I would have to dismantle the macine to get at the motor so a VFD would be out.


Choose your customers, don't let them choose you.
Joined: May 2005
Posts: 984
G
Member
It sounds like you'll need a special motor-generator set; sometimes called a 'rotary phase converter'.
It's a motor turning a generator. In your case, it sounds like you would get one that has a single phase motor driving a three phase generator.


Ghost307
Joined: Apr 2002
Posts: 7,282
Likes: 3
Member
Phil"
Ronkelectrical.com is a mfg of rotary and static phase converters.

Situation may be (is) they require ALL info on your load, so you may have to take it apart. How can you hook it up if you don't have the nameplate info? Voltage, HP, etc.



John
Joined: Mar 2005
Posts: 1,213
S
Member
Look for the THD rating; a solid state phase converter with an output filter will have low THD, and won't be an issue. They make them specifically for this purpose, it's no different than the inverter on a UPS.

A motor generator may be the cheaper solution, or may not be, solid-state is getting pretty cheap anymore.

Joined: Apr 2003
Posts: 362
Member
Just an update,
I let this slide as there were at least 4 other contractors looking at it. Interesting to note I was the only one who questioned the service 100a 1Phase residential. along with this 30a unit was: centreal A/C, oven, full size copier, 1 deep freezer(she wanted to ad 7 more), and the 20 space panel was full. Someone has already and completed the job. She told me it onlt took him 1.5 hrs. She also told me she signed a contract to fill a large order based on this machine before it was even wired/installed.

This being said I would like to know more about VF drives being used as phase converter. Does it effect the control? What is a THD rating? Why would you want to ever use a rotarty phase convertor if you coul use a drive?

Ob



Choose your customers, don't let them choose you.
Page 1 of 2 1 2

Link Copied to Clipboard
Featured:

Tools for Electricians
Tools for Electricians
 

* * * * * * *

2020 Master Electrician Exam Preparation Combos
2020 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Member Spotlight
waymag
waymag
dallas, texas, USA
Posts: 70
Joined: January 2002
Top Posters(30 Days)
dsk 7
Popular Topics(Views)
284,804 Are you busy
217,379 Re: Forum
203,721 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.7.5