Load Analysis Layout

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I have a 277/480 service with a 120/208 load in a restaraunt I am building. The a/c's (3) and vent hood are 480v. Layin lighting 277v. All other load will be gas or 120v. I understand the calculations fine, but I am not sure how to layout the written load analysis, because of the dual voltages. Can

Your Saturday Play Date

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UPDATE:  SOLVED by LeeV at 12:22 CDT

Are you about ready for a bonus riddle?  Tom and I are, and hope to have one for you by the 29th.  I’ll let you know for sure when we get the dates down.

For today, your riddle answer is found in the real world…

image from PhotoBucket

You are looking for a thing.

This thing is one object composed of separate, distinct parts.

It changes its shape and size.

The changes effect its function.


It does something important.

You’ll see this thing represented very well in popular fiction.

This has been associated with many important discoveries in several areas of astronomy.


Ahhhh… do you have the answer already?  You know where to find me…

…lurking…

…lurking…

Star Delta Motor Running Trouble

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when the 55 kw motor converts from star to delta it trips. But the contactor is latched on. so we started the motor in delta. it runs. when we reverted back to normal star delta fashion the same thing happened. when the timer and OLR were changed, the star contactor was on, but not the main contacto

Mapping the Dark Matter | Cosmic Variance

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Have any friends or colleagues who don’t believe in dark matter? Showing them this should help.

Dark Matter in Abell 1689

That ghostly haze is dark matter — or at least, an impression of the gravitational field created by the dark matter. This is galaxy cluster Abell 1689, in the constellation Virgo. (We feel compelled to add that information, in case you’re going to go looking for it in the night sky tonight or something.) It’s easy to see that the images of many of the galaxies have been noticeably warped by passing through the gravitational field of the cluster, a phenomenon known as strong gravitational lensing. This cluster has been studied for a while using strong lensing. The idea is that the detailed distribution of dark matter affects the specific ways in which different background images are distorted (similar to what was used to analyze the Bullet Cluster). Astronomers use up massive amounts of computer time constructing different models and determining where the dark matter has to be to distort the galaxies in just the right way. Now Dan Coe and collaborators have made an unprecedentedly high-precision map of where the dark matter is (paper here).

This isn’t all about the pretty pictures. We have theoretical predictions about how dark matter should act, and it’s good to compare them to data. Interestingly, the fit to our favorite models is not perfect; this cluster, and a few others like it, are more dense in a central core region than simple theories predict. This is an opportunity to learn something — perhaps clusters started to form earlier in the history of the universe than we thought, or perhaps there’s something new in the physics of dark matter that we have to start taking into account.

But the pretty pictures are certainly a reward in their own right.


Noise Reduction for AV installation

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An AV consultant on one of our projects has requested a separete isolation transformer to power all his rack and room mounted equipment. This is a 8 story building and the equipment is scatttered trhoughout the facilty. We are using a 600 Volt distribution system that uses ZigZag transfomers at each

Sizing of Drop Out Fuse

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I have a 100kVA 11kV/0.4kV Dyn11 type transformer. I want to connect a 20kW HydroPower plant to this 11 kV grid with this transformer. So, how can I calculate the size of Drop out fuse to connect HV side transformer to 11 kV grid? Or shoud I use MCCB??

The Sun blasts out a flare and a huge filament | Bad Astronomy

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Never forget: the Sun is a star, a mighty ball of ionized gas, and when a star throws a tantrum, even a small one is epic.

And the Sun just sent us a little reminder: NASA’s Solar Dynamics Observatory caught this amazing sequence of a sunspot blasting out a flare, then shooting out a long streamer of plasma:

[Direct link to YouTube video here]

Wow! So what are we seeing here?

SDO views the Sun in many wavelengths, and in this case we’re looking at ultraviolet light form the Sun so energetic it’s almost X-rays. The bright spot is actually a sunspot! They’re dark in the kind of light we see with our eyes* but can be very bright at other wavelengths. Sunspots are regions of intense magnetic field concentration; magnetic loops arc out of the spot, reach into space, then head back down. They seethe with vast amounts of energy, which can be released explosively under some conditions.

That’s what happened here. The magnetic field loops in Sunspot 1123 suddenly and cataclysmically released all their energy in the early morning of November 12, blasting it outward as a solar flare — you can see that as the intense flash of light coming from the bright region in the center of the video. This explosive event also launched a streamer of plasma off the Sun’s surface, flowing outward along the Sun’s magnetic field. Although the plasma is very hot, we see it silhouetted against the Sun’s surface, so it looks dark. This type of streamer is called a filament (had we seen it against the darkness of space, it would look bright, and be called a prominence). You can see it heading roughly in our direction at the end of the video. Don’t worry though, it won’t hit us!

And as if this weren’t enough, along with this event was a small coronal mass ejection. This is when a huge blast of subatomic particles is lofted into space by the Sun, and they sometimes (but not always) occur with flares. Happily for us, the CME will miss the Earth; when they hit they can cause damage to our satellites, as well as mess with our power grid here on the Earth’s surface.

However, don’t rest easy. We’re only at the beginning of this solar cycle, when the Sun’s twisted and complex magnetic field is starting to act up. It’ll build for the next two or three years, reaching a peak in late 2013 or 2014. We’ll probably see some pretty big flares and CMEs then, which means aurorae (yay!) and potential problems with our power grid (boo!). I doubt we’ll see the kind of damage breathless doomcriers will no doubt promulgate, but the thing is, we just don’t know. Will this be a big, violent peak, or a relatively quiet one?

We just have to wait and see. But I’m glad we have observatories like SDO watching the Sun so carefully. The more we know about it, the better.

Incidentally, I have quite a bit more detail about the Sun, spots, flares, and CMEs in chapter 2 of my book Death from the Skies! Just so’s you know.

* I’ll note that actually the plasma in the sunspot is very hot, and were it floating in space it would glow very brightly. It only looks dark because the Sun’s surface around it is so much brighter.

Related posts:

- The Sun kick starts its cycle once again
- One solar piece of flare
- The Sun rises again