Generators and Motors
[Home] - [HELP] - [Forums] - [Library] - [Photo Gallery] - [Groups] - [Classified Ads] - [Subscribe] - [Links] - [Books] - [Sponsors] -

Go Back   SmokStak > SmokStak® Vintage Electrical Equipment > Generators & Electric Motors General Discussion > Kohler Generators
Forgot Password? Join Us!

Notices

Kohler Generators Restoring, maintaining and operating vintage Kohler generators.

Kohler Generators

Kohler 6.5 KW 240V AC transformer symbol question


this thread has 7 replies and has been viewed 221 times

Reply
 
Thread Tools Display Modes
  #1  
Old 04-04-2019, 10:45:32 PM
Kenny Crenshaw Kenny Crenshaw is offline
Registered-I
 
Join Date: Nov 2015
Location: Millington, Tennessee
Posts: 51
Thanks: 1
Thanked 13 Times in 9 Posts
Default Kohler 6.5 KW 240V AC transformer symbol question

What type of transformer is this? The two legs of the AC run into the center of the transformer and lools like a lower voltage AC goes off into the selenium rectifier. I would like to know the name of this type transformer. Thanks
Attached Thumbnails
Click image for larger version

Name:	20190404_214012.jpg
Views:	55
Size:	60.9 KB
ID:	332080  
Reply With Quote
Sponsored Links
  #2  
Old 04-05-2019, 12:21:30 AM
Vanman Vanman is offline
Subscriber
 
Join Date: Aug 2011
Location: Mission Viejo, California
Posts: 5,397
Thanks: 8,167
Thanked 2,401 Times in 1,634 Posts
Default Re: Kohler 6.5 KW 240V AC transformer symbol question

I've always referred to it as a compounding transformer, but I don't know what Kohler called it. Thinking about it further, I think Kohler would have referred to it just by it's part number, which has to be looked up based on the set's spec number.

It functions more as a current transformer. The two heavy windings are not across the 240 volt output, rather they are in series with it such that all load current passes through the transformer. These windings have few turns. The other winding has many turns. In this way, the heavy load current is dropped to a few amperes for the rectifier and auxiliary field winding, but they are always proportional to each other. Thus, as load increases, so too does excitation, such that output voltage is held practically constant across the load range.

Keith

Last edited by Vanman; 04-05-2019 at 01:39:01 AM.
Reply With Quote
  #3  
Old 04-10-2019, 09:25:55 PM
LWB250 LWB250 is offline
Registered-III
 
Join Date: Oct 2008
Location: Tampa, FL USA
Posts: 1,430
Thanks: 27
Thanked 444 Times in 385 Posts
Default Re: Kohler 6.5 KW 240V AC transformer symbol question

If your generator still has the selenium rectifiers, replace them immediately! They will fail and in doing so will cause a cascade of failures of other components, mainly the transformer you're asking about.

A standard 25 amp bridge rectifier will do the job, and it's probably a god idea to put a stout MOV across the AC side of it to protect it.

Dan
Reply With Quote
  #4  
Old 04-11-2019, 08:46:40 PM
Kenny Crenshaw Kenny Crenshaw is offline
Registered-I
 
Join Date: Nov 2015
Location: Millington, Tennessee
Posts: 51
Thanks: 1
Thanked 13 Times in 9 Posts
Default Re: Kohler 6.5 KW 240V AC transformer symbol question

What is a MOV?
Reply With Quote
  #5  
Old 04-11-2019, 09:15:54 PM
Zephyr7 Zephyr7 is offline
Registered-III
 
Join Date: Mar 2017
Location: Davisburg, Michigan
Posts: 1,979
Thanks: 605
Thanked 1,116 Times in 761 Posts
Default Re: Kohler 6.5 KW 240V AC transformer symbol question

Quote:
Originally Posted by Kenny Crenshaw View Post
What is a MOV?
Metal Oxide Varistor. It’s basically a special type of resistor that normally doesn’t conduct, but very rapidly changes to heavily conducting above a certain voltage. In this way, an MOV serves to “clamp” (short out) high voltage transients.

MOVs are commonly used in small surge protectors. In larger surge protectors, gas discharge tubes (GDTs) are more useful. Sometimes both are used to combine the properties of both types of devices.

Bill
Reply With Quote
  #6  
Old 04-11-2019, 10:38:11 PM
Kenny Crenshaw Kenny Crenshaw is offline
Registered-I
 
Join Date: Nov 2015
Location: Millington, Tennessee
Posts: 51
Thanks: 1
Thanked 13 Times in 9 Posts
Default Re: Kohler 6.5 KW 240V AC transformer symbol question

Do I just loosen up A1 and A3 and screw the MOV in there with the leads?

Or do you mean across the AC side of the recifier?
Reply With Quote
  #7  
Old 04-11-2019, 10:55:22 PM
Power Power is online now
Registered-III
 
Join Date: Aug 2011
Location: New Jersey
Posts: 5,102
Thanks: 1,174
Thanked 3,010 Times in 1,773 Posts
Default Re: Kohler 6.5 KW 240V AC transformer symbol question

Quote:
Originally Posted by Kenny Crenshaw View Post
Do I just loosen up A1 and A3 and screw the MOV in there with the leads?

Or do you mean across the AC side of the recifier?
First get rid of Selenium rectifier. When it blows, toxic fumes come out. Replace as LWB suggested. If you use a high PIV bridge, don't need MOV. Bridges are so inexpensive, because of environment, I usually go double amps and 500 volts or so.
Reply With Quote
  #8  
Old 04-11-2019, 11:07:11 PM
Kenny Crenshaw Kenny Crenshaw is offline
Registered-I
 
Join Date: Nov 2015
Location: Millington, Tennessee
Posts: 51
Thanks: 1
Thanked 13 Times in 9 Posts
Default Re: Kohler 6.5 KW 240V AC transformer symbol question

I ordered a rectifier kit from Kohler. I think it comes with the proper resistor to make up for the lower resistance of the silicon diodes. It was $25, but it is coming to my house and I won't have to hunt for one. I hope it comes with instructions.
Reply With Quote
Reply

Bookmarks


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

F o r u m Jump

Similar Threads Chosen at Random
Thread Thread Starter F o r u m Replies Last Post
wacker/kohler 180 Hz 240v genset (HGG)kohler miraclewhip Kohler Generators 17 01-30-2019 12:27:09 PM
120V -> 240V Voltage Regulator Sensing Transformer? Generac? Part #? jones09641 Generators & Electric Motors General Discussion 12 10-06-2015 08:50:28 PM
Transformer for kohler controller box jolsen30041 Kohler Generators 2 04-30-2009 05:45:21 PM
Kohler 5.5cm21 120v change to 240v marvink Kohler Generators 0 12-28-2007 11:26:19 PM
240v step down transformer John Stewart Generators & Electric Motors General Discussion 2 01-13-2004 07:13:41 PM


Use "Ctrl" mouse wheel to change screen size.
All times are GMT -4. The time now is 05:44:05 PM.

Smokstak and Enginads site search!


All use is subject to our TERMS OF SERVICE
SMOKSTAK® is a Registered Trade Mark - A Community of Antique Engine Enthusiasts
Copyright © 2000 - 2019 by Harry Matthews P.O. Box 5612 - Sarasota, FL 34277