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Type: Posts; User: gar

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1. ## Thread: Power Calculation Unbalanced 3 Phase

by gar
Replies
18\$\$
Views
218

### 141122-1823 EST The approximate currents are...

141122-1823 EST

The approximate currents are 10.1, 5.77, and 7.22 for your sketch 2. Your other currents are OK.

The calculations are:

3 kW 3000/600 = 5 A
4 kW 4000/600 = 6.6667 A
1 kW...
2. ## Thread: Power Calculation Unbalanced 3 Phase

by gar
Replies
18\$\$
Views
218

### 141122-1554 EST You misunderstood my comment...

141122-1554 EST

You misunderstood my comment on average measurement of an AC sinewave vs an RMS measurement of that same curve.

An average measurement of a half rectified full cycle sine wave...
3. ## Thread: Power Calculation Unbalanced 3 Phase

by gar
Replies
18\$\$
Views
218

### 141122-1358 EST What does pulse width...

141122-1358 EST

What does pulse width modulation mean? Is this phase control of SCRs, or is it "bang-bang" control of the contactor?

If you are dealing with sine wave current, then vector math...
4. ## Thread: Power Calculation Unbalanced 3 Phase

by gar
Replies
18\$\$
Views
218

### 141122-1307 EST Is the resistive load wired as...

141122-1307 EST

Is the resistive load wired as a delta or wye?

32 resistors are not evenly divisible by 3. Thus, inherently unbalanced.

Is there any phase shift or on-off cycling of the...
5. ## Thread: Multiple Large Surges Residential

by gar
Replies
9\$\$
Views
193

### 141122-0840 EST What is an Ultra? The C-H...

141122-0840 EST

What is an Ultra? The C-H website seems to use the name across several models.

The statement that fire comes out of whatever outlet the customer is near implies that fire would...

by gar
Replies
2\$\$
Views
135

### 141121-2113 EST Pedro jr: See...

141121-2113 EST

Pedro jr:

See http://en.wikipedia.org/wiki/Cogeneration .

,
7. ## Thread: How many TV's, DVD players, etc.

by gar
Replies
9\$\$
Views
199

### 141121-1241 EST If you have a composite video...

141121-1241 EST

If you have a composite video base band signal with a coaxial cable communication path, the source will probably be 50 ohms and the far end of the cable should be terminated with...
8. ## Thread: Multiple Large Surges Residential

by gar
Replies
9\$\$
Views
193

### 141121-1153 EST At our shop we had a problem...

141121-1153 EST

At our shop we had a problem one time. This is a three phase open delta system with a center tapped single phase transformer. Center tap is grounded. The single phase transformer...
9. ## Thread: Step Up Trans Residential Main

by gar
Replies
7\$\$
Views
147

### 141120-2057 EST Fundamentally you need about a...

141120-2057 EST

Fundamentally you need about a 1500 VA transformer so go with 2.5 or 5 kVA to get a lower impedance. Primary 112 V with a 10 V secondary as a boost source.

.
10. ## Thread: Lowering current output from supply transformer

by gar
Replies
5\$\$
Views
165

### 141120-2033 EST sdickson: I do not know how...

141120-2033 EST

sdickson:

I do not know how your circuit works.

I assume the current transformer at the top of the last photo is the one under test.

The transformer on the right has...
11. ## Thread: Lowering current output from supply transformer

by gar
Replies
5\$\$
Views
165

### 141120-1627 EST Your drawings are too small to...

141120-1627 EST

Your drawings are too small to read easily, and I don't want to wade thru all the detail either.

So to the basics.

You need a transformer with a rating of possibly 50 A on...
12. ## Thread: Transient Voltage Spikes - What is normal or acceptable?

by gar
Replies
31\$\$
Views
1,049

### 141120-1211 EST well grounded: If you have...

141120-1211 EST

well grounded:

If you have a positive transient spike of 61 V peak centered at a voltage positive zero crossing, then will this trigger a transient event? The peak of this...
13. ## Thread: Transient Voltage Spikes - What is normal or acceptable?

by gar
Replies
31\$\$
Views
1,049

### 141120-0911 EST well grounded: A list of...

141120-0911 EST

well grounded:

A list of times with no amplitude and duration information is of little value other than to indicate something occurred.

What does 50% RMS 120 V mean? For...
14. ## Thread: 90 amp altenator

by gar
Replies
16\$\$
Views
402

### 141119-0646 EST donmic: My ITT Reference...

141119-0646 EST

donmic:

My ITT Reference Book provides the following information for copper:

.... # 14 ......... # 12 ......... # 10

2.525 ........... 1.588 ........ 0.9989...
15. ## Thread: Home Automation in new construction

by gar
Replies
21\$\$
Views
705

### 141118-2354 EST codetalker: I would...

141118-2354 EST

codetalker:

I would describe your approach as a kluge.

I believe you now may be required to run a neutral to each switch box. Also your approach does not eliminate the...
16. ## Thread: 45 KVA transformer max amperage?

by gar
Replies
23\$\$
Views
515

### 141118-1309 EST What is the total cost of two...

141118-1309 EST

What is the total cost of two 25 kVA single phase vs one 75 kVA three phase transformer?

What is the core loss comparison of the above two possibilities?

.
17. ## Thread: Transient Voltage Spikes - What is normal or acceptable?

by gar
Replies
31\$\$
Views
1,049

### 141117-1421 EST well grounded: I don't see...

141117-1421 EST

well grounded:

I don't see any transients in your latest waveforms. All I see is the small square ripple on the sine wave which appears to be your instruments sampling rate. If...
18. ## Thread: Help!! Power Quality Issues Multiple Office UPS's Going Off Randomly!

by gar
Replies
44\$\$
Views
2,080

### 141117-1415 EST Eh40: The TED 1000 had a 1...

141117-1415 EST

Eh40:

The TED 1000 had a 1 second integration time, the TEDs since then are 2 seconds or worse even though TED states 1 second.

From the manual the Amprobe that 5 S electric...
19. ## Thread: Transient Voltage Spikes - What is normal or acceptable?

by gar
Replies
31\$\$
Views
1,049

### 141117-0814 EST The first scope trace appears...

141117-0814 EST

The first scope trace appears to show a single full cycle moderately high frequency, relative to the power line frequency, oscillation that is triggered somewhere near the line...
20. ## Thread: Help!! Power Quality Issues Multiple Office UPS's Going Off Randomly!

by gar
Replies
44\$\$
Views
2,080

### 141115-1045 EST 5 S electric: You have...

141115-1045 EST

5 S electric:

You have spent a lot of money and time trying to solve your problem. Had you used the correct instrumentation and correctly I believe the problem area could have...
21. ## Thread: Help!! Power Quality Issues Multiple Office UPS's Going Off Randomly!

by gar
Replies
44\$\$
Views
2,080

### 141114-1725 EST 5 S electric: I have never...

141114-1725 EST

5 S electric:

I have never worked with your Amprobe instrument, but looking at the manual you need to have it setup for Voltage Anomalies. I don't believe you have done that. I...
22. ## Thread: Home Automation in new construction

by gar
Replies
21\$\$
Views
705

### 141114-1035 EST masterinbama: Of the RR...

141114-1035 EST

masterinbama:

Of the RR failures you encountered what was the cause of failure?

I have had no coil burnouts because of my system design, but I have had several that lost...
23. ## Thread: Home Automation in new construction

by gar
Replies
21\$\$
Views
705

### 141114-1018 EST codetalker: Can you clarify...

141114-1018 EST

codetalker:

Can you clarify your last post.

What is it that you actually want to learn?

You list yourself as an EE. What were your schools, degrees, and areas of...
24. ## Thread: Home Automation in new construction

by gar
Replies
21\$\$
Views
705

### 141113-2117 EST codetalker: The GE RR relay...

141113-2117 EST

codetalker:

The GE RR relay has no UL or NEC problems.

For a fairly complete description see:
https://www.vikingelectric.com/Images/img/043180/GE%20RS2-37.pdf

.
25. ## Thread: Home Automation in new construction

by gar
Replies
21\$\$
Views
705

### 1411130-1611 EST codetalker: The GE RR...

1411130-1611 EST

codetalker:

The GE RR relay is a mechanically bistable relay with silver contacts, and a set and reset coil set.

Thus, a wired logical "or" set of momentary switches in...
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