T-7 overheated!

[Herman Trivilino]

Fineline, have you checked the voltage at the outlet where you plug in your Tormek? See what the voltage is, especially under load. It could be that there is an issue with the wiring in your house, or with the voltage being supplied to your house. I would check simple things first like the outlet itself and the circuit breaker itself. Many times these parts wear out under heavy use and are just fine until you use them for heavy duty service. They are easy and inexpensive to replace.

[Jan]

Thank you Stig for your report!

I have used the time when the original Tylers machine was tested in Sweden, to understand why an idle running motor may be warmer then a motor under full load. I hope to understand it now, and I will try to explain here why is it so.

Single-phase AC induction motors are known by the names of the starting method used. In my opinion our motors are Permanent-Split Capacitor motors (PSC). These motors have run-type capacitor, which is permanently in series with the auxiliary winding. In the figure bellow there is a winding scheme for a PSC motor.


It is common misconception that a PSC motor running below its full load will run cooler and more efficiently. On the contrary, single-phase motors may become very warm at small loads or when run idle.

Why is it so? The efficiency of an idle running PSC motor drops to zero, and hence all the consumed electric power is converted to heat power. Whereas, near full load rating, the motor efficiency is greatest. The consumed power is partitioned into shaft power and the heat power. It may happen that an idle running motor generates more heat than the same motor running at full load.

In the figure bellow there is power triangle relating apparent power to real (consumed) power for a small PSC motor.



The figure shows, that the heat power (upper red bar) produced by an idle running motor is larger than the heat power (lower red bar) produced by a full loaded motor.

During our grinding and honing the motor load is only some 5% of full load.
Jan

[Ken S]

Having worked as a telephone troubleshooter for thirty five years, Stig's explanation of Tormek's testing and findings sounds quite reasonable to me. Sometimes trouble just does not show any symptoms. It sounds like the Tormek people ran the proper tests. The switch sounds like a good possibility. Changing out the switch would have been an acceptable fix. However, Tormek chose to replace the entire unit even before testing the original unit. I call that exceptional service.

Herman,

The motor in the T7 is rated at 200 watts input. That's less than two amps. (Starting current will be higher with any motor.) Standard residential circuits are either fifteen or twenty amp capacity. While it is entirely possible that there may be a house wiring problem, a Tormek load would not stress the circuit.

Ken

[Fineline]

Hi,
We got the machine about 2 weeks ago and tested the machine for several hours with 122 Volt, a higher current, to see how warm we could get it and if it stopped.
The result was about 57 degree celsius/ 135 degree Fahrenheit witch is within tolerance and we got a lower temp when we measured on the motor housing. It worked all the time.

We can´t find anything wrong with it but it could be the switch since a click was noticed. The motor itself can´t give a click sound but the switch can.
The test did not show why it stopped. Even the switch works as it should.

We can't do much more than to test it and the customer have a new machine that works fine.

Stig

Stig,
What a coincidence. The unit I have also has this 'click' when I press to turn on the machine. I'm wondering if it might be some form of arcing or voltage spike. Anyway, if you have further findings on the switch, please share with us.
Thanks,
fl

[Fineline]

Fineline, have you checked the voltage at the outlet where you plug in your Tormek? See what the voltage is, especially under load. It could be that there is an issue with the wiring in your house, or with the voltage being supplied to your house. I would check simple things first like the outlet itself and the circuit breaker itself. Many times these parts wear out under heavy use and are just fine until you use them for heavy duty service. They are easy and inexpensive to replace.

Hi Herman,
I don't have a overheating problem with my machine. OP is Tyler.
fl

[Fineline]

Thank you Stig for your report!

I have used the time when the original Tylers machine was tested in Sweden, to understand why an idle running motor may be warmer then a motor under full load. I hope to understand it now, and I will try to explain here why is it so.

Single-phase AC induction motors are known by the names of the starting method used. In my opinion our motors are Permanent-Split Capacitor motors (PSC). These motors have run-type capacitor, which is permanently in series with the auxiliary winding. In the figure bellow there is a winding scheme for a PSC motor.


It is common misconception that a PSC motor running below its full load will run cooler and more efficiently. On the contrary, single-phase motors may become very warm at small loads or when run idle.

Why is it so? The efficiency of an idle running PSC motor drops to zero, and hence all the consumed electric power is converted to heat power. Whereas, near full load rating, the motor efficiency is greatest. The consumed power is partitioned into shaft power and the heat power. It may happen that an idle running motor generates more heat than the same motor running at full load.

In the figure bellow there is power triangle relating apparent power to real (consumed) power for a small PSC motor.



The figure shows, that the heat power (upper red bar) produced by an idle running motor is larger than the heat power (lower red bar) produced by a full loaded motor.

During our grinding and honing the motor load is only some 5% of full load.
Jan

Thanks for sharing Jan.
I remember reading in the manual that no load generates more heat or something to that effect.
Good post anyway.
fl

[Jan]

Thanks, FL. Yes, my explanation confirms the statement in the Tormek Manual paragraph "The Motor is Running Hot". The sentence reads: "The heat developed by a single phase motor is considerable – even when idling when it actually reaches its highest temperature". 

[Ken S]

I was a troubleshooter for the telephone company for thirty five years. That thought process has become ingrained in me. I think Tormek in Sweden ran very logical tests. In the real world trouble often does not exhibit symptoms. The noisy telephone line may be quiet and show no measurable fault when the technician tests it. In this case, Sweden tested no trouble with the motor or switch, but suspected a bad switch. Replacing the switch would, in my opinion, have been an adequate resolution. Instead, Tormek sent the customer another brand new unit completely at Tormek's expense. And, the new unit was sent to the customer even before Tormek examined the problem unit. I consider this outstanding service.

Ken

[jeffs55]

I take back my comment that said we would never hear about this again and implied that Tormek would simply bury it. There is no higher compliment than one from me as you have really got to do good. I also apologize as I am not to proud to say that I was wrong.

[OnealWoodworking]

Fineline, have you checked the voltage at the outlet where you plug in your Tormek? See what the voltage is, especially under load. It could be that there is an issue with the wiring in your house, or with the voltage being supplied to your house. I would check simple things first like the outlet itself and the circuit breaker itself. Many times these parts wear out under heavy use and are just fine until you use them for heavy duty service. They are easy and inexpensive to replace.

Good advice.

It could also be that the guy was running his Tormek on an already overloaded circuit and killed it that way.

If the OP had invested in a cheap 'Kill-A-Watt' meter he could have very quickly ruled out any issues related to his power supply. Most guys never think to check until AFTER they have killed their motors.

[stevebot]

I have often run my Tormeks, 2000s and T-7s, for 4 hours straight on hot summer days with no problems.
I am thinking you have a defective motor and/or sensor and would ask the distributor to replace it.