form wound vs. random wound

[cvirgil]

Anyone know the differenc bewteen these two types of windings for low voltage generators?

 

[rbulsara]

Visit web site of Kato alternators. Or somehow contact their engineering and you shoud be able to get a publication on the subject.

 

[alehman]

You may be able to get something similar from Caterpillar.
Form wound means the coils are wound so as to minimize the voltage stress on the winding insulation. Some people feel this provides an advantage in the ability of the insulation to withstand high voltage transients (i.e. waveform notching caused by rectifier loads). The alternative (less expensive) is what is called random wound.

Personally, I have clients who have literally hundreds of random-wound gensets feeding various rectifier and electronic loads, and I know of only one winding failure in ten years.

 

[alehman]

Also, medium voltage units are always form-wound.

 

[rbulsara]

Here it is

http://www.kato-eng.com/fwrw.pdf#search='kato form wound'

I normally won't do this, but this was easy. I would expect you do your own search and try to find answers yourself, may be post here as info.

 

[petronila]

Hello Cvirgil,

Form Wound Coil is a coil made with SQUARE or RECTANGULAR wire.

Random Coils is a coil made with ROUND wire.

The main difference with this two winding types is the wire type.
In form windings you most insulate all coil wrapping mica and glass tape arround all coils and for large machines you could change a part of the winding in some failure cases, in random windings you insulate the slots and place insulation between each end coil.
I would prefer the form wound coils due to this winding will last more time in operation and for design point you can use high volt/turn ratio, also the mechanicall stress due to magnetical forces is avoided due to the coils will fit OK on the slot.

Regards,

petronila