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Type: Posts; User: junkhound

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by junkhound
Replies
16\$\$
Views
826

### When windstorm forecast here we start the gensets...

When windstorm forecast here we start the gensets to be sure one of them starts right off.

Have a 2 kW for camping, 1.8 kW for small tools, 220V 3kW, 8 kW and 15 kw just to be sure something...
2. ## Thread: Transformer and rectifier math

by junkhound
Replies
30\$\$
Views
1,549

### PFC boost circuit, typical output for 3 phase...

PFC boost circuit, typical output for 3 phase 120V l-n is 350 to 400 Vdc. :p
3. ## Thread: Transformer and rectifier math

by junkhound
Replies
30\$\$
Views
1,549

### here is the common circuit for simple 6 diode 3...

here is the common circuit for simple 6 diode 3 phase bridge
You can get EVERY voltage, current, and power dissipation from this type FEA model This is ORCAD PSpice, you can download a free...
4. ## Thread: Transformer and rectifier math

by junkhound
Replies
30\$\$
Views
1,549

### For those without analysis tools or a math...

For those without analysis tools or a math capable scope, here are visual waveforms, 100 Vrms line to neutral. (If you can read it, would not enlarge further)
Note that difference between avg and...
5. ## Thread: Transformer and rectifier math

by junkhound
Replies
30\$\$
Views
1,549

Scenery - how much is the load?

You can buy off the shelf 5 kW Vienna bridge 3 phase PFC rectifiers a lot cheaper than designing a straight rectifier with big caps.
About the size of 2 packs...
6. ## Thread: Heating element math

by junkhound
Replies
22\$\$
Views
829

### Think it is the Fibonacci series if you count how...

Think it is the Fibonacci series if you count how many different CONNECTIONs can be made, including not using some of the elements in the count.

Then it is 1, 2, 3, 5, 8, 13, 21, 34, 55,...
7. ## Thread: Heating element math

by junkhound
Replies
22\$\$
Views
829

### Did this once years ago but barely passed...

Did this once years ago but barely passed statistic back in school,

has a (n!) expression or 2 in the formula is all IIRC. :roll:

maybe n+n!+(n-1)! too lazy tonight to figure it out ...
8. ## Thread: neher mcgrath calcs

by junkhound
Replies
8\$\$
Views
496

### re: render it immediately obvious how to devise...

re: render it immediately obvious how to devise an excel spread sheet to my ends

Nope, don't think you are missing anything, not intellectually challenging but would be tedious

was Just...

by junkhound
Replies
4\$\$
Views
643

### Folks who are personal friends are all retired...

Folks who are personal friends are all retired from PSE so have no inside source, but,

Surprised you cannot find what you need on PSE website, but they have revised part of the site recently.
...
10. ## Thread: PSC motors banned?

by junkhound
Replies
12\$\$
Views
540

### Is the 'cannot' technical or due to regulations?

Is the 'cannot' technical or due to regulations?
11. ## Thread: PSC motors banned?

by junkhound
Replies
12\$\$
Views
540

### re: based on fully " Fradulent " pseudoscience...

re: based on fully " Fradulent " pseudoscience

I take it the 'science' you refer to is the anthropogenic component of climate change?
R290 (propane) works better than R-22 (or 410A) and since...
12. ## Thread: PSC motors banned?

by junkhound
Replies
12\$\$
Views
540

### Thank you, that is likely the regulation...

Thank you, that is likely the regulation involved, as the hvac-talk comment did mention a new regulation taking effect this week.
13. ## Thread: PSC motors banned?

by junkhound
Replies
12\$\$
Views
540

### hvac-talk, was looking for info about R290...

hvac-talk, was looking for info about R290 regulations
14. ## Thread: PSC motors banned?

by junkhound
Replies
12\$\$
Views
540

### PSC motors banned?

Saw a mention of PSC motors to be banned from compressor units in HVAC equipment.

First have ever heard of this, anyone have any detailed information?

The implication was that if R290 replaces...
15. ## Thread: If a motor runs on 230V at 47A, how many amps will it draw at 208V?

by junkhound
Replies
42\$\$
Views
2,698

### Here is a 230V PSC 184 frame motor draws 49 A...

Here is a 230V PSC 184 frame motor draws 49 A driving 4000psi 4GPM pressure washer.

Nameplate of only 24.6A, 5 HP. Does not overheat.

Does have supplemental cooling, just thought to throw...
16. ## Thread: If a motor runs on 230V at 47A, how many amps will it draw at 208V?

by junkhound
Replies
42\$\$
Views
2,698

### Since you have gotten so many non-consistent...

Since you have gotten so many non-consistent answers, to start with there is NOT 'the formula', there are sets of formula since you need to take the load into account.

Here is a simple experiment...
17. ## Thread: European appliance voltage compatabilty?

by junkhound
Replies
2\$\$
Views
248

### Don't forget 50 Hz, but a thermal seal product...

Don't forget 50 Hz, but a thermal seal product likely has nothing frequency or timing critical in it. Any ac motor will run faster by 6/5.

98% sure it will work on 240V 60Hz with just a 240 Vac...
18. ## Thread: Why 3ph power supply?

by junkhound
Replies
5\$\$
Views
589

### For a 50W 24 V supply, 3 phase is actually MORE...

For a 50W 24 V supply, 3 phase is actually MORE complex. NO advantage, disadvantage.

Nowadays, a simple single phase supply with a switch mode PWM PFC front stage has 0.99PF and < 1% harmonics,...
19. ## Thread: If a motor runs on 230V at 47A, how many amps will it draw at 208V?

by junkhound
Replies
42\$\$
Views
2,698

### Assuming single phase induction motor, depends...

Assuming single phase induction motor, depends greatly on the type of load.

Constant power load? Positive displacement pump? Centrifugal pump? Fan?, etc. Reduction in speed at 208 could result...

by junkhound
Replies
17\$\$
Views
1,034

### Pricey, but even wallyworld sells brushless car...

Pricey, but even wallyworld sells brushless car alternators.

...
21. ## Thread: Where do we use 1.73 when calculating 3 phase power

by junkhound
Replies
23\$\$
Views
2,031

### Well, For a perfectly balanced system, they are...

Well, For a perfectly balanced system, they are the SAME BY DEFINITION of tangent. My comment was for a non-balanced system.
22. ## Thread: Where do we use 1.73 when calculating 3 phase power

by junkhound
Replies
23\$\$
Views
2,031

### For the OP, here is a picture and basic...

For the OP, here is a picture and basic equations, might be easier to understand than just verbiage.
Note that sqrt 3 is valid (as already noted by multiple responders) ONLY for a balanced system ...
23. ## Thread: Where do we use 1.73 when calculating 3 phase power

by junkhound
Replies
23\$\$
Views
2,031

### And as a side question for the student, as to why...

And as a side question for the student, as to why or how, one may ask, did sqrt 3 become the 'go to' number rather than tan(60)?

After all, if not a perfectly symmetric 3 phase system, the...

by junkhound
Replies
17\$\$
Views
1,034

### Nearly all DC systems I work with that are engine...

Nearly all DC systems I work with that are engine driven use AC 3 phase generators and full bridge rectification or PFC electronics to convert to DC.

Even railroad engines are 'switching' (pun...

by junkhound
Replies
6\$\$
Views
390