Recent content by GMIEE

When choosing a type of advanced meter to install, would you recommend socket mount meters either directly on or near the transformer feeding a building or would you go for installing a panel mount meter in the existing main distribution panel? I am wondering about the pro/cons of each setup.

I am looking to develop a similar price indexing system, but from the electrical side of things.

Also, JRLAKE, may I ask what power quality analyzer that is you used?

Inrush current?

How does one determine the instantaneous trip setting of an MCCB? A software I am using wants me to input the instantaneous trip setting of an MCCB. There is no manual setting that I see though. Isn't this a factory determined level that should already be in the software?

Is it possible to calibrate a 1% CT (by use of metering software correction) with the use of a CT test box to act as a higher say 0.5% precision CT?

I guess my real question is if the turns ratio can be measured and corrected, and the phase angle error can be measured and compensated for, why are CT's still given 1% accuracy? Where does the remaining error originate?

What is the consensus on where CT error originates? Is it in the turns ratio not being exactly as given, or would you say it is the phase lag?

What I don't understand about the 2 second rule is aren't these questions all about arc flash? Arc flash occurs in an almost instantaneous manner does it not? How then does the 2 second rule apply to anything more than the arc itself?

Looking at a list of fault currents provided to me by the utility, a large hangar with a 500 kva 12.47kv/480v transformer has a fault current of 11kA. The small building next door with a 150kva transformer 12.47kv/208v has a fault current of 33kA. These are fed from the same substation. Why is...

I'm running an arc flash analysis and the system has a 60 kVA UPS attached. Upstream of this UPS I am getting numbers of 0.5 cal/cm^2, but I look on the side that the UPS would be powering and it jumps to 136 cal/cm^2. Is this a common effect of a UPS in arc flash analysis? I find it...

If I am given a maximum fault current at a transformers secondary from the utility and the transformers impedance, how do I get the fault current that is seen at the primary side of the transformer (in order to get clearing times with the transformers protective device). Xmfr: 3 phase, 150Kva...

Yeah, I thought I might have to do that. One other quick question. Should the bolted fault current be based on an infinite bus calculation, or the actual fault current?

Hello, I am performing and arc flash analysis and have run into a problem figuring out what clearing time to use. I am given the bolted fault current at the transformer secondary and the transformer specifications. The 150Kva transformer has secondary of 208V and a fault current of 32000 A. I...