I'm reviewing the preliminary drawing package for a small (5MW) solar farm. The design engineer has specified low energy analogue (LEA) voltage sensors instead of PTs for the customer owned recloser.
Does anyone have concerns or reservations about LEAs? Is the accuracy comparable to PTs...
Has anyone in this forum taken any Power Engineering courses through University of Wisconsin - Madison's distance learning program? UW has a good reputation and the course offerings look good. I don’t know how to what degree a good school necessarily has a good distance learning program.
I’ve...
I'm working on a job where the utility wants the ability to remotely turn off two solar inverters remotely. The utility will run fiber to the inverters. I don't know what communications protocol they will use.
The question I have is how to convert from a signal on fiber to the trip signal the...
I've been having a problem when I print from AutoCAD to pdf. I'm trying to print in monochrome, but text comes out in two tones, where some of the letters are lighter and some are darker. The same thing happens to some of the fillets. When I plot a hard copy everything comes out black (as it...
Can anyone recommend a table listing resistance values for various copper and aluminum conductor sizes? I would usually use Tables 8 or 9 of the NEC, but I'm writing something for a customer in Canada.
Thanks,
John
Has anyone seen the loss of a single phase in a 120/240V residence? I expect it would be unlikely, since center tapped 120/240V transformer is usually connected to a single phase of the 3-phase distribution system,so the loss of a single phase of the distribution would lead to the loss of both...
My boss pointed me to a short course given by EUCI. The agenda looks good, it's relevant to my work, and it's close to home, so I'm thinking about registering, but I'm curious if anyone here has experience with EUCI's training. If they aren't a quality outfit, my time could be wasted...
I got an email from a head hunter earlier today. He didn't give a lot of details, but it's a small world and I recognized the opening he's trying to fill. It's been listed on the company's website for a while and I've been thinking about applying for it.
This might be a naive quesion...
I came across a former junior coworker's resume on a networking site. He had vastly overstated his achievements and job responsibilities. For example he said he "managed" one job where I recall he couldn't read any of the drawings or even talk intelligently to the electrician.
Has anyone...
I have a question regarding voltage drop calculations. I'm sure it's painfully simple, but it's been troubling me for a little while.
The electric services where I work are predominantly 120/208VAC 3-phase. Apartments and single family homes get 120/208VAC "single phase" or network service...
I am in a situation where I am being asked to stamp a drawing set done by another engineer. The drawings are for a large grid tied solar electric system and the utility wants the drawings stamped before they will allow interconnection. The system is already installed and the firm that did the...
I am working on a job where the electrical contractor pulled unshielded, twisted pair Cat 5 cable for RS485 communications. I know RS485 is usually run in shielded twisted pair, and I am wondering if this will work. The runs are all in dedicated metal conduit, which I think would function as a...
I'm sizing wires for a 3 phase 45 kW inverter in a photovoltaic system. The inverter only requires the 3 phase conductors, but the kWh meter we're installing requires a neutral. Does the neutral need to be the same size as the phase conductors? I can rationalize making the neutral smaller...
We recently installed a 20 kVA 120/208V Wye/ 208V Delta isolation transformer, with the Wye connected to the utilty service and the delta side connected to an inverter for a photovoltaic system. With the inverter off and the neutral of the inverter connected on the utility side, we measured 55A...
