Thats the standard lightning surge class 3- indoors. its what we use to test MOV's and surge suppressors. it will make short work of something that's not protected. Potato's explode. . .
EFT is to simulate the relays on the old elevator or a worn switch in your old blender.
Who, me???
Jn
Ps. I had to point out the humor of a high school summer job experience being used to "teach" someone who has done it for 25 years at a ridiculously high level of accuracy.
And with your 25 years of experience are you going to discuss what the gaps do to the end result?
Mea culpa
And I thought Mr. Marsh on a pole waving his wallet, his Bentley, and an -140dB measurement was offensive. I was dead wrong, it can go much deeper and broader.
And I thought Mr. Marsh on a pole waving his wallet, his Bentley, and an -140dB measurement was offensive. I was dead wrong, it can go much deeper and broader.
For this application fuse the input and use a GFCI on the output of the isolation transformer. The '7000 has two transformers and each is connected to a seperate GFCI. The center taps of the transformers are switchable to ground so you have either option available. The GFCI is essential (and required in the NEC here in the US) for safety. Its also a good common mode choke.
Hmm , let's see ...
High school, you, figure late 60's ?
In the intervening 50 years give or take, people seemed to have developed a better sense of what needs to be done to the iron profiles in both the rotor as well as the stator to properly modulate the flux rate of change in the coils.
Also, they better understand what the flux density does to the permeability, in both rotor and stator.
Were the slots straight axial lay or did they twist helically? Do you know what the twist does.
It's not the gaps that matter, it's the flux rate.
None of this would have been explained to you then. Nor did they have FEA loaded on a laptop.
You should read about all this, it really is pretty cool.
Jn
Yes. All balanced transformers from places like Equi=tech have GFCI breakers.
Table showing test classification numbers and other info here: http://www.st.com/content/ccc/resou...df/jcr:content/translations/en.DM00080038.pdf
Okay, that sounds good from a safety perspective.
However, still seemingly inappropriate to use a polarized socket indicating a neutral strapped to ground somewhere upstream if in fact the socket pin is actually wired as a 60v hot rather than a 120v neutral. If the applicable regulatory agencies approve it, then I guess that makes it an authorized exception.
I cut my teeth on high power systems. Accelerators, Fusion energy …. From the 230KV sub-station to the accel PS and everything in between. From 120vac to 2 ea 230Kv 10MVA transformers 3 stories tall. And control room grounding, for computer room to console to machine. Plus the low Z building grounding and the experiment grounding. I coordinated it all - design, installation, test and did the low Z, grounding design for all systems.
Here is one of 6 control rooms for the 10KG H.E. control and diagnostics. One of 6 control rooms. Note the huge ultra isolation, triple shielded power transformer hanging from the ceiling to power these racks. A lot of equipment from floor to ceiling... grounding, wiring, etal. Power, control signals, diagnostics signals, their wiring and grounding of each systems.
[HE = High Explosives] BTW - 10Kg of the HE being created for nuclear weapons would flatten a reinforced concrete bunker. Which this building was itself. test was in a huge containment vessel/chamber. should a test chamber explode.. the building had designed in over-pressure paths to relieve the building pressure.
Blow up photo and look/read notes. I know a thing or two about power. You are not given the responsibility unless you are really good.
THx-RNMarsh
Here is one of 6 control rooms for the 10KG H.E. control and diagnostics. One of 6 control rooms. Note the huge ultra isolation, triple shielded power transformer hanging from the ceiling to power these racks. A lot of equipment from floor to ceiling... grounding, wiring, etal. Power, control signals, diagnostics signals, their wiring and grounding of each systems.
[HE = High Explosives] BTW - 10Kg of the HE being created for nuclear weapons would flatten a reinforced concrete bunker. Which this building was itself. test was in a huge containment vessel/chamber. should a test chamber explode.. the building had designed in over-pressure paths to relieve the building pressure.
Blow up photo and look/read notes. I know a thing or two about power. You are not given the responsibility unless you are really good.
THx-RNMarsh
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An externally hosted image should be here but it was not working when we last tested it.
They aren't strapped to ground, the 60v "neutral" is not. But you have CT to ground.
Now put a cap between the two 60v lines. Then measure the DM and CM results.
Results will vary depending on C value and on transformer used (L). For the competitive ones... see if you can better my results that I have shown. Arm chair critics need not apply.
THx-RNMarsh
Proud to be an extremist, beer drinking, partying, deplorable, money grubbing, audio enthusiast.
Results will vary depending on C value and on transformer used (L). For the competitive ones... see if you can better my results that I have shown. Arm chair critics need not apply.
THx-RNMarsh
Proud to be an extremist, beer drinking, partying, deplorable, money grubbing, audio enthusiast.
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Are we supposed to support again your hatred of Mr Marsh? With each and every of his messages, you are at his calves like an edgy pout.
That clears up a worry I had. Are you able to divulge the trip current? Whilst doing a bit of background research to see if anyone had ever actually published measurements of an electrostatic shield on a domestically sized toroid I came across this https://download.schneider-electric...File_Name=0150DB1601.pdf&p_Doc_Ref=0150DB1601 from Schneider. Now this is a very different application size wise, but interesting to note that, they (abeit with something to sell) found the shields could make things worse.
My take away though is just to reinforce that you have to get the grounding design right first before you worry about anything else.
JN,
The generators being rewound were not exactly new, easily two or three times my age. Probably still in service.
Yes FEA is a handy tool. Local product!
One friend worked there and had gotten a new boss. He was doing a group demonstration when a question from the floor asked about a specific application. He just answered of course the software could do it. His new boss was ticked off he didn't demonstrate that specific application. The boss didn't get it the questioner had done those applications so many times that he already could do such an analysis on the classic back of an envelope much faster than it would take to even load the problem.
So what is the distortion on a current generator offering?
I note Westinghouse and General Electric have both taken a beating in the power generation business.
Then we could discuss power transformer temperature rise. Normal design is half resistance losses and half core losses. Core losses also seem to add distortion.
BTY I do have a back up generator. Distortion is high enough it looks bad on an oscilloscope. Unit is 15 years old.
The generators being rewound were not exactly new, easily two or three times my age. Probably still in service.
Yes FEA is a handy tool. Local product!
One friend worked there and had gotten a new boss. He was doing a group demonstration when a question from the floor asked about a specific application. He just answered of course the software could do it. His new boss was ticked off he didn't demonstrate that specific application. The boss didn't get it the questioner had done those applications so many times that he already could do such an analysis on the classic back of an envelope much faster than it would take to even load the problem.
So what is the distortion on a current generator offering?
I note Westinghouse and General Electric have both taken a beating in the power generation business.
Then we could discuss power transformer temperature rise. Normal design is half resistance losses and half core losses. Core losses also seem to add distortion.
BTY I do have a back up generator. Distortion is high enough it looks bad on an oscilloscope. Unit is 15 years old.
So, you based an over-reaching argument about magnetic fields/gaps/harmonic distortion on an opinion formed when you were 16 years old, rewinding generators that were built at around 1910. Hmmm.
Had I realized that, I would have deferred to your experience base, what I do is clearly a very small subset of your summer job experience.
For motors and generators designed and built in the last 70 or 80 years, very careful attention has to be paid on the harmonic distortion. Anything other than pure sine reflects on the system as torque ripple. Mechanically, it is important to eliminate as much torque ripple as possible, hence the details.
Even the gearing, as involute straight cut gears produce torque ripple by design, so they use helical cut gears to reduce that significantly. Key word helical, as that is also what they tend to do with stators and rotors depending on need.
Jn
I did start researching modern motor design when looking at whether there was a better way to do DD turntable motors. There was and the Japanese knew it even in the 70s but kept that for their best stuff. I stopped looking when I realised
a) the cost of really low torque ripple motors
b) the fact that the basic technics green motors are actually as good as it gets for the job, even though they are a very sub-optimal pole:slot ratio (again that was saved for the good stuff).
I am still intrigued as to whether modern waveform synthesis can overcome some of this ripple by knowing where things are and adjusting accordingly or whether that is t*rd polishing.
a) the cost of really low torque ripple motors
b) the fact that the basic technics green motors are actually as good as it gets for the job, even though they are a very sub-optimal pole:slot ratio (again that was saved for the good stuff).
I am still intrigued as to whether modern waveform synthesis can overcome some of this ripple by knowing where things are and adjusting accordingly or whether that is t*rd polishing.
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