Stator Rust
Stator Rust
(OP)
I have some fractional hp, 120vac motors that we have found quite a bit of rust on the rotors. These are rated at about 35oz.ins. of torque and I need every bit I can get. Will the rust on the rotors drive up the amp draw or reduce the torque output or both? Any help is appreciated.





RE: Stator Rust
RE: Stator Rust
Small cast rotor motor I don't think there are any rotor cooling air ducts like large motor, so doesn't seem likely any concern about reduced cooling.
The only other thing I can think of is that if there is very large removal of metal or change in structure=> magnetic properties of metal, the effective airgap may increase, resulting in increased magnetizing current and decreased breakdown torque.
Just my thoughts.
RE: Stator Rust
If it is a concern for you, why don't you paint the rotors?
RE: Stator Rust
There isn't usually a rust problem when there are rotor windings which are impregnated, and often they are subsequently spray-coated with an anti-tracking varnish. It is not uncommon to varnish induction motor rotors either.
RE: Stator Rust
Is the primary reason corrosion prevention? Or prevent rotor bars from coming loose?
What's the reason for using varnish or other resin instead of other coatings more specific to those functions (corrosion protection or mechanical retention)? Nothing to do with electrical properties, right? Just because it is readily available at a motor shop?
RE: Stator Rust
http://www.edtcorp.com/c.applications/01poultry.htm
http://www.finishing.com/181/20.html
http://www.skatedork.org/pr/pr9.htm
http://www.grogz.com/bora.htm
http://www.canyonchasers.net/equip/shop/tls_ohlins.htm
http://www.ebearing.com/news2001/news127.htm
http://www.pirate4x4.com/tech/billavista/PR-35Spline/in...
http://www.walleyesinc.com/walleyeinc2/boatstorage.htm
etc. for more info on rusty bearings
RE: Stator Rust
The treatment was intended for corrosion protection. The insides of the DC traction motor stators (confusingly referred to as "the magnet") were also varnished internally for the same reason. This air-drying varnish (red or grey usually) was applied by spraying and went over the impregnation varnish - the whole stator assembly including the frame having already received a VPI.
I don't know what the practice is on industrial induction motor rotors.
RE: Stator Rust
Normally cage rotor bars are caulked along the length to prevent looseness. Impregnating the cage rotors is unnecessary. A finishing air drying varnish is applied on the rotor cylindrical surface to prevent surface rusting.
Kumar
RE: Stator Rust
RE: Stator Rust
RE: Stator Rust
Ever heard of protective paint on the rotor out-gassing at temp. The Chlorine gas then ate into the varnish which started the corrosion