VFD V/Hz for large propellor fan ?

[petersonra]

They had over 500 VFD'S in the large hospital/ research center campus that I retired from. My self or a union electrical contractor would replace bad drives & drives for replacing MCC starters. We would pay a extremely talented Danfoss tech maybe $200 to perform start ups that stretched out the warranty & free labor to 3 years. He had trouble with a drive and had to go to his truck to get a 1" thick book for programming. He made changes in one of two parameters to get the 75HP VFD . Told me he attended a two day class just on programming drives.

One of our engineers just came back from a 5-day class on one of the Allen Bradley VFDs. I'm not sure how you even know where to look with some of these drives as far as what parameters to set for some of these really unique applications. But the thing is that for most applications, maybe 99%, most of those parameters just don't make any real difference.

 

[garbo]

One of our engineers just came back from a 5-day class on one of the Allen Bradley VFDs. I'm not sure how you even know where to look with some of these drives as far as what parameters to set for some of these really unique applications. But the thing is that for most applications, maybe 99%, most of those parameters just don't make any real difference.

I had a strange fault code that was not in the drive Manuel so I called our very talented drive tech and told me to change one parameter and drive started working. I went to an Allen Bradley drive class just for a special drive they produced for Goss newspaper presses back in the 1990's. Majority of the time these drives worked as a brake keeping a constant tension on 3,000 pound paper rolls. Drive would determine the speed of expiring rolls of newsprint then perform a speed match and over 98% of the time perform a splice on paper moving over 25 MPH. I was lucky enough to talk to one of the engineers who designed it. Told me it took 10 man years to perfect the program. They would not tell me how much each drive coat. We had twenty if them between our two presses and heard they produced ably only sold a thousand of them.

 

[Besoeker3]

I had a strange fault code that was not in the drive Manuel so I called our very talented drive tech and told me to change one parameter and drive started working. I went to an Allen Bradley drive class just for a special drive they produced for Goss newspaper presses back in the 1990's. Majority of the time these drives worked as a brake keeping a constant tension on 3,000 pound paper rolls. Drive would determine the speed of expiring rolls of newsprint then perform a speed match and over 98% of the time perform a splice on paper moving over 25 MPH. I was lucky enough to talk to one of the engineers who designed it. Told me it took 10 man years to perfect the program. They would not tell me how much each drive coat. We had twenty if them between our two presses and heard they produced ably only sold a thousand of them.

I'm glad you had good drive tech - we did did our our complete manufacturing including system projects ourselves. Inverters,, Static Kramers, DC drives, synchros etc .

 

[recklessconduct]

Thanks, guys. Taking a step back and looking at the larger picture, what I also need to do is dig into the configuration of the other, older VFD that is controlling the other propellor cooling fan. There is only one PLC/PID controlling both, so best to try to set the VFDs up as close to each other as possible.

Seems the vast multitude of parameters in VFDs are like solutions looking for problems...

I might have a similar situation with a solution but not quite sure yet. I am in no way an expert and what I know is self taught, no formal training. As far as I can understand my thoughts on this start basic. A/C induction motors work because of a magnetic rotating field. This field usually is produced remotely like in a power station, nuclear reactor, generator in your back yard, etc. There is no direct electrical connection between this generator or power station and the motor sitting on the bench top in your garage. It works via "flux" generated remotely. For me to be able to control the speed of this motor I need to be able to control how fast this magnetic field moves about a center point within the motor. I can control this a few different ways but thru my observation it seems like changing motor design isn't the answer and this frequency control is being done outside of the motor but close enough to accomplish fine tuning. For us the the cheapest and easiest way would be to ask the power company to take it Lite on the coal or rods to make less steam and slow the Generators resulting in a slower frequency but heck if I could do that then why don't I just own the whole country lol? We need cheap, quick/easy retrofits to what we already have in place. Wether we control frequency by changing a motors design which can end up being a trigonometric function therefore "square" doesn't seem economical for a retrofit. What I do see is something "linear" that I can easily install and it's cheap. We Americans love the Chinese! Thou we are always arguing and making threats to each other, sometimes even busting the other nose or splitting a lip, we love each other and wouldn't be able to survive on this planet without one another. My brother Jason doesn't know anything about electricity but when I stopped by his house one very hot summer day he had made a " swamp cooler" for the dog. He had a cooler full of ice with ducted air forced thru the cooler and directly over the ice. It was pleasant because the air was slightly moist and very cool and the air moving was fast and under pressure. He could control temperature by slowing airflow. He had two fans controlled in one place by a dial he turned. His doggy swamp cooler had been working under a pretty constant load for a few months now and didn't show any signs or points of weakness. Now back to what you are trying to do; control two cooling fans from a central point but how to combine PLC function of the old and new drives. You need a quick, simple, cheap retrofit from the Chinese. I have your answer....

 

[drcampbell]

... he had made a " swamp cooler" for the dog. He had a cooler full of ice with ducted air forced thru the cooler and directly over the ice. It was pleasant because the air was slightly moist and very cool and the air moving was fast ...

It's very likely that this device took humidity out of the air. The temperature of the ice and meltwater being below the dewpoint, moisture in the air would have condensed out of the air and onto the ice.

 

[kwired]

At 2000 feet above sea level, it's probably not important.

But what am I talking about? (gee, never heard THAT before!) Usually, it means turning the fan a little faster, to move a greater volume of air, to move the same mass of air, to achieve the same heat transfer. Sometimes, it means installing a bigger fan, or one with more blades.

I agree, that is not high. Where I am might be close to 2000 feet. I know nearest town is about 1700 or so, but I know they are lower than where I am as they are in valley next to a river.

Much of extreme eastern Colorado is over 3000 feet and some areas even over 5000 before you are close enough to see mountain peaks. 5000 might be where you start to consider atmosphere pressure for such things.

 

[kwired]

I might have a similar situation with a solution but not quite sure yet. I am in no way an expert and what I know is self taught, no formal training. As far as I can understand my thoughts on this start basic. A/C induction motors work because of a magnetic rotating field. This field usually is produced remotely like in a power station, nuclear reactor, generator in your back yard, etc. There is no direct electrical connection between this generator or power station and the motor sitting on the bench top in your garage. It works via "flux" generated remotely. For me to be able to control the speed of this motor I need to be able to control how fast this magnetic field moves about a center point within the motor. I can control this a few different ways but thru my observation it seems like changing motor design isn't the answer and this frequency control is being done outside of the motor but close enough to accomplish fine tuning. For us the the cheapest and easiest way would be to ask the power company to take it Lite on the coal or rods to make less steam and slow the Generators resulting in a slower frequency but heck if I could do that then why don't I just own the whole country lol? We need cheap, quick/easy retrofits to what we already have in place. Wether we control frequency by changing a motors design which can end up being a trigonometric function therefore "square" doesn't seem economical for a retrofit. What I do see is something "linear" that I can easily install and it's cheap. We Americans love the Chinese! Thou we are always arguing and making threats to each other, sometimes even busting the other nose or splitting a lip, we love each other and wouldn't be able to survive on this planet without one another. My brother Jason doesn't know anything about electricity but when I stopped by his house one very hot summer day he had made a " swamp cooler" for the dog. He had a cooler full of ice with ducted air forced thru the cooler and directly over the ice. It was pleasant because the air was slightly moist and very cool and the air moving was fast and under pressure. He could control temperature by slowing airflow. He had two fans controlled in one place by a dial he turned. His doggy swamp cooler had been working under a pretty constant load for a few months now and didn't show any signs or points of weakness. Now back to what you are trying to do; control two cooling fans from a central point but how to combine PLC function of the old and new drives. You need a quick, simple, cheap retrofit from the Chinese. I have your answer....

I don't agree with that. Yes there is flux in the generator yes there is flux in the end use motor. Transmission between the two involves energy transmitted via conductors and via other transformations along the way. That flux in the motor is created by passing current through core/coils within the motor which creates the magnetism needed to operate the motor. The rotating field is simply because of multiple voltage/currents being out of phase with one another. We even create such phase relationships locally when dealing with single phase motors with simple induction methods and/or by using capacitors to create a phase shift.