I was going over the “Instructions” for my HLW 4-4-0. They state that I should not use PWM because it will eventually “fry” (my word, not theirs) the electric motor.
I thought it didn’t make any difference to the motor.
That’s the gouge?
I think the lower frequency PWM (like 200-500 HZ) that some used in the past may have had a tendency to overheat a motor at low speeds. All of my controls run at 20KHZ, so no annoying motor buzz due to the PWM, and I certainly haven’t had any of my motors “fry”, or any of my customer’s that I know of.
Whilst it is true that PWM can generate extra heat in the motors, PWM is unlikely to hurt regular iron “cored” motors as the iron core can dissipate heat reasonably well. Some manufacturers, such as AristoCraft, leave vent holes around their motors to assist cooling.
PWM could cause significant damage to (so called) “coreless” motors unless the PWM frequency is over 5 KHz.
RCS runs at 18 KHz and the new BELTROL version runs at 20 KHz.
I understand some of the Kalamazoo 4-4-0’s had sound systems fitted, so, perhaps they were being cautious and left the warning in the instructions for non sound locos, as PWM can badly affect some sound systems .