Re: Testing motors

Bertho Boman wrote:

> From: Bertho Boman <boman@...>
>
> I have a variety of motors that I have collected over the years.

> I know how to test for the motor constants and basically for
> max continuous power.
>
> I have not seen any practical reference to find out the max peak current

> allowed without permanently demagnetize the motor and
> degrade the performance.

This is very hard to do. The only way to do it accurately is to heat the motor to a rather
high operating temperature (which makes most magnets much easier to demagnetize) and
then put in higher and higher current pulses, checking after each one for a change in Kv,
indicating that the magnets have lost some field. This, of course, ruins the motor, or at
least degrades it. There is no way to measure the max peak current. A motor engineer,
knowing all the details of every material and dimension in the magnetic circuit, and also
knowing the very fine details of the magnet composition, can get a fairly good idea of what
current it can handle before demagnetization, but they still have to test a few to destruction
to be sure (and to be sure their magnet maker is giving them what they are paying for in
magnet quality.)

The only reference that will be much use is a data sheet from the motor manufacturer.
These can be obtained for standard motors from most makers, but custom OEM
motors can leave you guessing.

Jon