What size thermal?

[Uglydog]

Mr. jim18655 has all the right answers.

You have two choices. Only wire one speed of the motor with the proper size heaters installed or get a two speed magnetic starter and install all six heaters of the correct size. Why six? Three for each speed same as your single speed contactor needs three for one speed. Why? Code requirement for proper safe operation. If your starter only has two overloads it is out of date and non code compliant. One heater is required for each current carrying leg of a 3 phase motor circuit. Sorry, have to keep up with the times. Anything else is bad info.

Great information!!
Thank you all.
Code, OSHA, and other regulations aren't usually in place just to be a pain...
There are real and appropriate reasons.
We all make choices. We live and die by those choices. Yes, sometimes we die by the choices we make.
If I understand your post above. Then I need to rewire all the old iron I have.
Hmmmm...
Thank you for all of your responses, I got some shopping to do.
And I'm not sure that merely loading W50 is the best answer.

Daryl
MN

 

[Ulma Doctor]

Great information!!
Thank you all.
Code, OSHA, and other regulations aren't usually in place just to be a pain...
There are real and appropriate reasons.
We all make choices. We live and die by those choices. Yes, sometimes we die by the choices we make.
If I understand your post above. Then I need to rewire all the old iron I have.
Hmmmm...
Thank you for all of your responses, I got some shopping to do.
And I'm not sure that merely loading W50 is the best answer.

Daryl
MN

you can spend a lot of time and money making things code book "right".
the electrician that you are supposed to hire to change a light bulb or any other electrical device will cost you more than you paid for the piece of equipment
the men that designed that machine are not idiots, that's why the machine still operates today albeit at a reduced capacity due to low thermal cutoff.
i'm probably going to sound like a heretic... but,your machine is not going to explode and free society is not going to end for putting a couple w50 heaters in and trying the unit out to see if it works out.
it's not like there is no circuit protection and if there is a line to line short the thermal will do it's intended function even there is only 2 heaters.
you can spend a couple thousand to make it right until the code changes or less than 50 and make chips for fun

make the decision that works best for you

 

[John Hasler]

Ulma Doctor writes:

it's not like there is no circuit protection and if there is a line to line short the thermal will do it's intended function even there is only 2 heaters.

The function of the heaters is not to protect against fault currents. That's the purpose of the circuit breakers or fuses. The heaters are there to protect against motor overload. You need them because circuit breakers or fuses sized to pass the starting current (which is the same as the locked rotor current) can not provide adequate overload protection.

There are improbable motor faults which could result in the unprotected leg drawing enough current to set the motor on fire without tripping the breaker. IMHO if you are worried about that sort of thing you should use a GFI.

Just put the W50s in and be happy. If you stall the motor and don't notice in time they'll trip before it catches fire.

 

[Senna]

Personally, if any of my machinery has only two heaters per circuit, and if it's been running happily like that for 60+ years, I'm not going to worry for one second about the lack of a third heater.
I'm certainly not going to spend the cubic dollars required to get those three heaters.

 

[rdhem2]

The function of the heaters is not to protect against fault currents. That's the purpose of the circuit breakersor fuses. The heaters are there to protect against motor overload. You need them because circuit breakers or fuses sized to pass the starting current (which is the same as the locked rotor current) can not provide adequate overload protection.

Thank you John Hasler. Could not have said it better my self.

You folks who panic at the thought of spending a buck on the electrical that make your old piece of crap even run amuse me. I love old stuff. I love to make it like new. I love to use it after I am done. All my machines are "OLD".

Let us take a Allen Bradley Size "0" starter from 1955 for example. These units only have two heaters. Go scrounge up another obsolete starter or just the thermal overload portion. Probably $5. You will probably pay more for the heater for it then the overload costs. Remove one of the overload blocks. Mount it next to the two existing blocks. (Usually on the right side so it looks factory). Install some wires to connect it all up. Install the third properly sized overload. Wammo, bammo. You have fixed everything for next to nothing and I guarantee you will have learned something too. You will know how to fix the problem instead of just thinking you do and poo pooing code and safety. This is just one example for one brand of starter.

Now you are code compliant and your motor is properly protected and it is still old school. Now the biggie is when the operating coil gives up the ghost, or the solder pot in the overload craps out. You can't go to the store, buy parts and fix it without paying through the nose from a regular supplier. So your machine is down until you scrounge more old obsolete repair parts. Or else you put in new parts, close the door so no one can see it, and move on.

Your call!

 

[Uglydog]

rdhem2,
If I understand your post correctly. Installing a third w50 thermal would do the job.

However, following another post in this thread. Then in this two speed motor application I will need an additional three W? thermals for the 3 amp circuit, as the w50s only protect the 8amp.

If correct, can I safetly install the w50s to control all power to the speed switch and then some w? to the 3amp after they leave the safety switch enroute to the motor? I write w? as I will need to look up the corrrect thermal for the 3amp.

If my understanding is correct, this shouldn't be terribly difficult or expensive.

This Walker Turner 1100 DP is turning out to be fairly accurate for a DP and has a nice speed selection.

Thank you,
Daryl
MN

The function of the heaters is not to protect against fault currents. That's the purpose of the circuit breakersor fuses. The heaters are there to protect against motor overload. You need them because circuit breakers or fuses sized to pass the starting current (which is the same as the locked rotor current) can not provide adequate overload protection.

Thank you John Hasler. Could not have said it better my self.

You folks who panic at the thought of spending a buck on the electrical that make your old piece of crap even run amuse me. I love old stuff. I love to make it like new. I love to use it after I am done. All my machines are "OLD".

Let us take a Allen Bradley Size "0" starter from 1955 for example. These units only have two heaters. Go scrounge up another obsolete starter or just the thermal overload portion. Probably $5. You will probably pay more for the heater for it then the overload costs. Remove one of the overload blocks. Mount it next to the two existing blocks. (Usually on the right side so it looks factory). Install some wires to connect it all up. Install the third properly sized overload. Wammo, bammo. You have fixed everything for next to nothing and I guarantee you will have learned something too. You will know how to fix the problem instead of just thinking you do and poo pooing code and safety. This is just one example for one brand of starter.

Now you are code compliant and your motor is properly protected and it is still old school. Now the biggie is when the operating coil gives up the ghost, or the solder pot in the overload craps out. You can't go to the store, buy parts and fix it without paying through the nose from a regular supplier. So your machine is down until you scrounge more old obsolete repair parts. Or else you put in new parts, close the door so no one can see it, and move on.

Your call!

 

[rdhem2]

Thank you for asking. Walker Turners are good gear at any level, unsimilar to DELTA in my experience!

Ok now to the question at hand. Trying to explain simply as possible, your two speed motor has to be treated as two completely separate motors that should never, I repeat never, be allowed to be energized at the same time. Factory two speed starters appear to be two complete three phase starters side by side mounted on the same backplate similar to a reversing starter. If you can find a reversing starter of the correct size it can easily be modified to make it a two speed. Keep an eye open for that as you cruise the antique shops looking for parts. They are electrically interlocked and also mechanically interlocked to positively prevent them from being energized/operated at the same time.

Imagine what would happen if you told your motor to run at 1800 rpm and then said run at 1200 rpm all at the same time. One winding speeding up, one winding slowing it down. I'll bet it would become like you, rather hot and confused when someone demands you do two things at the same time. This second winding/speed is why you also need three more heaters. Because basically they are connected to a completely separate motor.

I totally agree that it will not hurt to run the DP short term on oversize heaters to check out and trouble shoot it. You are right there monitoring it and probably not putting any real continuous load on it. Just don't forget to change them to the correct ones later on.

Lets think of one thing no one here seems to grasp. Overloads on the motor are a time/load dependant issue. Very light overload for a short period of time, like when you jam a drill bit, no one notices. Now you chuck up a 1 33/64" bit to drill out those 109 pilot holes you just drilled. Heavy load for a long period of time. Now is the time for that overload relay to shine. When the heat in the motor builds up and you continue to run it for extended period of time it trips out. Protecting your motor. If you had had an Amprobe on it you would have seen the amperage going way over full load and jumping all over. But the motor continued to run because of the time factor.

That is when even one heater size too large is too much if the motor windings give out before the thermal trips! You are not even aware all this is going on. But they are doing their jobs. Monitoring the current flow.

All of these dumb codes and requirements should be very familiar to you Uglydog. The National Electrical Code (NEC) is just a fraction of the entire National Fire Protection Agency (NFPA)library. In a nutshell the code is meant to provide for two main occurrences. Protection from fire for life and property and death by electrocution. As I always say "Wire it as the electrical inspector and insurance adjuster want to see, then we would not even need this conversation." I would not be proud to have electrocuted my grandkid with the same knowingly poor practices that burned my shop down! Cost is nothing compared to a dead body! Wire it right or hire it done. That is what this site is for, correct, good information.

Sorry Uglydog, I get a little passionate on the subject from time to time and the influx of crap. You are going to have one helluva drill press when you are done. My project at the moment is a Cincinnati #2 Tool & Cutter Grinder. From about the middle 60's I think. Came in wired 480v 3ph only. I only have 230v 1ph. Gonna be fun.

 

[Uglydog]

Agreed, the codes exist for a reason. Having said that, I am not an electrician.
I've installed this two speed / reverse switch which prevents the possibility of engaging both motor speeds simultaneously. Thanks to you an Ulmadoc coaching me in December.
If I add a third leg W50 before the switch.
And then add whichever thermal is appropriate (I'll need to study the Allen Bradley charts again) for the slow speed and install them between the switch and the motor would that be safe and appropriate?

If so, the next trick is me figuring out how to do this...
The subsequent trick(s) will be doing it for all my "single speed" 3phase motors.

Thoughts?

Thank you,
Daryl
MN

Thank you for asking. Walker Turners are good gear at any level, unsimilar to DELTA in my experience!

Ok now to the question at hand. Trying to explain simply as possible, your two speed motor has to be treated as two completely separate motors that should never, I repeat never, be allowed to be energized at the same time. Factory two speed starters appear to be two complete three phase starters side by side mounted on the same backplate similar to a reversing starter. If you can find a reversing starter of the correct size it can easily be modified to make it a two speed. Keep an eye open for that as you cruise the antique shops looking for parts. They are electrically interlocked and also mechanically interlocked to positively prevent them from being energized/operated at the same time.

Imagine what would happen if you told your motor to run at 1800 rpm and then said run at 1200 rpm all at the same time. One winding speeding up, one winding slowing it down. I'll bet it would become like you, rather hot and confused when someone demands you do two things at the same time. This second winding/speed is why you also need three more heaters. Because basically they are connected to a completely separate motor.

I totally agree that it will not hurt to run the DP short term on oversize heaters to check out and trouble shoot it. You are right there monitoring it and probably not putting any real continuous load on it. Just don't forget to change them to the correct ones later on.

Lets think of one thing no one here seems to grasp. Overloads on the motor are a time/load dependant issue. Very light overload for a short period of time, like when you jam a drill bit, no one notices. Now you chuck up a 1 33/64" bit to drill out those 109 pilot holes you just drilled. Heavy load for a long period of time. Now is the time for that overload relay to shine. When the heat in the motor builds up and you continue to run it for extended period of time it trips out. Protecting your motor. If you had had an Amprobe on it you would have seen the amperage going way over full load and jumping all over. But the motor continued to run because of the time factor.

That is when even one heater size too large is too much if the motor windings give out before the thermal trips! You are not even aware all this is going on. But they are doing their jobs. Monitoring the current flow.

All of these dumb codes and requirements should be very familiar to you Uglydog. The National Electrical Code (NEC) is just a fraction of the entire National Fire Protection Agency (NFPA)library. In a nutshell the code is meant to provide for two main occurrences. Protection from fire for life and property and death by electrocution. As I always say "Wire it as the electrical inspector and insurance adjuster want to see, then we would not even need this conversation." I would not be proud to have electrocuted my grandkid with the same knowingly poor practices that burned my shop down! Cost is nothing compared to a dead body! Wire it right or hire it done. That is what this site is for, correct, good information.

Sorry Uglydog, I get a little passionate on the subject from time to time and the influx of crap. You are going to have one helluva drill press when you are done. My project at the moment is a Cincinnati #2 Tool & Cutter Grinder. From about the middle 60's I think. Came in wired 480v 3ph only. I only have 230v 1ph. Gonna be fun.

 

[rdhem2]

Mr. Uglydog;
We are so close yet so far away. A two speed motor is treated as two separate motors wound in one stator. Hence you have six motor leads, therefor you require six heaters, three for high speed, three for low speed. That is why your starter needs two separate contactors and thermal overload blocks.
Please refer to the following ebay item as an example of your need--eBay item number:171162137945. The gold colored items towards the bottom in the picture are the heater elements in this example. All six of them. After looking on ebay there are some really good prices for what is offered. Now that I am no longer in business I will use their services.

When in business you must have warrantees and guarantees so you must go with back-up or you will not remain in business for long. One year on installed devices and labor in this state. One little phase to phase short can blow up and melt down thousands of dollars of gear in the blink of an eye. I am way off track.

You referred I believe, to the overloads being ahead of the contactor. The proper order of gear and current flow is from the source to the safety disconnect at the motor starter location, then the contactor portion of the motor starter, then the thermal overload block with the heaters and finally to another disconnecting device at the motor location. Then finally the motor. Other devices may be added as desired or needed to the line or control wiring.

The selector switch you show in the first picture could be made to work, so it appears. But does nothing to address your overload situation. It appears to be a glorified drum switch. The second picture of the AB starter could have a third overload installed and be used to run one of the two speeds with the proper heaters installed. Or you could install it as pictured and let the third leg do as it wishes.

Now before I get my ream job of being anally overcharged. This is the proper, code implied way to do the installation as I understand it. I could make it work with barbed wire on porcelain insulators nailed to split ceder fence posts. Safe? No. Run. Yes. Happy now? And we have only scratched the surface. If you do not understand my terminology, you should probably not be doing this kind of work. Some of us were actually TRAINED and SCHOOLED in the subject. Probably why I have such a haughty attitude over those educated by Dad's uncle Fred's, next door neighbor's cousin who worked as an apprentice electrician for two weeks. I really enjoy trying to help people understand what can be a very confusing subject, but it pisses me off to be criticized by those who obviously do not have a clue and it does absolutely nothing for the person trying to learn. I am beginning to believe that the only people being allowed to answer questions on this topic should be able to prove their knowledge and education on the subject. Do you consult a mortician for a toothache?

Are you detractors happy now? I in no way say to rewire your entire shop. What I do say is if you are going to fix up an old tired machine with new bearings, new bushings, new paint, new whatever else it needs, include the electrical that makes the sorry thing even work to begin with. An electrical inspector has jurisdiction over NEW and ALTERED electrical installations. The insurance adjuster may control your future.

 

[Uglydog]

rdhem2,
Thank you for your patient and complete response.

From my education, training, and experience in EMS, Fire, and disaster preparedness/response safety always comes at a price.
We need to make decisions for ourselves about how we will individually invest in personal risk and benefit management.
Unfortunately, sometimes decisions effect the lives, health, and prosperity of others.

Thank you once again for you contributions to HM.

Daryl
MN