T202 new motor run cap, motor now runs very hot HELP

[Papus]

I just replaced my T202's original Aerovox 1.25 microfarad 660V motor run cap (240V 50Hz mains here) with a pair of new 2.5uf 450V caps in series.
Motor starts and runs fine.
The TWG spins freely by hand (with motor attached), and roughly ten seconds spin down time from turning off the motor.
Motor & TWG were last oiled about 9 months ago.
I've noticed the motor is very hot, almost too hot to touch, after running my T202 for about 45 minutes.


New caps are pictured.

HELP! I don't want to burn out my motor.
240V 50Hz Hammond self-starting synchronous motors are even more rare than tonewheel Hammonds around here...

[Jyvoipabo]

May be the wiring is not correct.
The pic show the wiring of a L100.
A 220k resistor should be paralleled with one cap.
JP

[geoffbrown]

This is quite normal for these motors to get hot after extended running

[tpappano]

I just started my E100 and will measure the actual temp. In the meantime, if you can keep your hand on it you're likely ok. If you have to pull away in less than 5 seconds, it might be too hot 8)

[tpappano]

Mine is running 128 degF (52 degrees above ambient), within the '5 second' rule but too hot to keep a hand on continuously 8)

[Papus]

May be the wiring is not correct.
The pic show the wiring of a L100.
A 220k resistor should be paralleled with one cap.
JP

What is the purpose of the resistor?
What is its power rating? - the photo looks like a 5w carbon comp

[tpappano]

The resistor ensures that both capacitors discharge when the power is switched off to prevent "surprises" when you are working around them 8)

Looks to me like a 2 or 3 watt MOX (flameproof metal oxide film), an excellent choice

[Papus]

This is quite normal for these motors to get hot after extended running

45 minutes isn't a long time compared to a recording session or a gig.
I'm curious - is there any original data from Hammond regarding operating temperatures?
From what I can tell, it seems people are only discovering hot motors after changing the run cap, probably because the motor wasn't previously very accessible whilst the original cap was in place, but these new caps are smaller and make it easier to reach the motor.
Also most people would want to check their motor after installing a new cap, in case of incompatibilities.
What I'm getting at is this: were these motors always running hot in the period 1960-2000's, but people never noticed until they started changing the caps in the last 20 years?

[tpappano]

I looked at the nameplate on my E100 motor. It is rated to draw 35 watts and run 40 degC (72 degF) temp rise, so mine is actually running 20 degF cooler than it is rated. After 2 hours it has stayed at 128 degF

[Papus]

I looked at the nameplate on my E100 motor. It is rated to draw 35 watts and run 40 degC (72 degF) temp rise, so mine is actually running 20 degF cooler than it is rated. After 2 hours it has stayed at 128 degF

Where are you getting “Rated to run 40°C temp rise”?
This isn't written anywhere on my motor.
Mine says Duty Cycle “Cont. 40°C” - I interpret this to mean that the motor is not designed to run hotter than 40°C continuously, not “40°C above ambient room temperature”.
Nowhere is it stated that the figure of 40°C is a “rise above ambient”.
Think about it: on a 100°F (38°C) outdoor stage, the motor would be at 172°F (78°C) - that's unthinkable and would surely lead to burnout/fire hazard.
My instincts tell me these figures in the 55+°C range being bandied about as normal are way above spec.
The only hard evidence I have is my label which is attached to this post.

[geoffbrown]

The 40 degree cont means the motor can be run continuously at 40 degrees ambien,t it does not refer to the motor run temperature ,70 degrees under those conditions is not usual

[tpappano]

Well, I goofed us up 8) The 40C rating on the label is indeed the ambient rating for the motor when running at full load. The allowable temp rise depends on the insulation 'class', A,B,F,H, 105,130,155 or 180 degC respectively. So at 40C ambient a class A motor is allowed a 65C rise to reach 105C max winding temperature.

Here is a document that explains how it works:

https://www.powertransmission.com/is...dor-basics.pdf

I can't see if the insulation class is on the label, but one may have to go to complete factory specs to find that. In an application such as this it probably is class A

[Papus]

Well, I goofed us up 8) The 40C rating on the label is indeed the ambient rating for the motor when running at full load. The allowable temp rise depends on the insulation 'class', A,B,F,H, 105,130,155 or 180 degC respectively. So at 40C ambient a class A motor is allowed a 65C rise to reach 105C max winding temperature.

Here is a document that explains how it works:

https://www.powertransmission.com/is...dor-basics.pdf

I can't see if the insulation class is on the label, but one may have to go to complete factory specs to find that. In an application such as this it probably is class A

Thanks - good sleuthing.
I'm sure I'm not the only spinet owner who wants a concise answer on this, these motors are difficult to source in 50Hz land

[tpappano]

I should have thought about what I was posting earlier, considering that I manufacture speed controllers for induction motors, and not have left out insulation class, the key spec for temperature 8) You can see that even class A insulation allows the motor to run at ambient temps high enough that you wouldn't even want to play the organ 8)

[Papus]

I should have thought about what I was posting earlier, considering that I manufacture speed controllers for induction motors, and not have left out insulation class, the key spec for temperature 8) You can see that even class A insulation allows the motor to run at ambient temps high enough that you wouldn't even want to play the organ 8)

I hope you are correct.
I really don't want to harm my 50 year old motor.
I'm awaiting arrival of a laser digital thermometer so I can take an accurate reading off the chassis and off the windings....
It's time for some hard empirical science on this issue

[geoffbrown]

We had a thread on this about a year ago,I have a t524 which reaches 70 degrees C after about 10 minutes with ambient temp of 30 degrees C ,how long can they be left running? I have have no idea and neither does anyone else apparently.
The reason for the heat buildup is partly due to the poor electrical efficiency of the shaded pole motor and possibly internal friction in the motor bearings and or tone generator,some people say they have solved this problem by stripping the motor and cleaning gummed up bearings