Just as desertfox has described, when mounted at one end, mechanically an arrester is a cantilevered beam. The mechanical strength of it is determined by how much torque the arrester can withstand without damage. When making attachments to the arrester it is important to verify the...
Had to read your post twice to make sure I understood what you are asking. Section 11 covers enclosures (fences) but does not address this specific issue. I don't think that NESC addresses it anywhere. This being said a general rule of thumb we use is to strive to keep 10 feet around a fence...
Thanks for the response 7anoter4. I saw that and the graphs shown "look" like they come from some standard. They also show in Figure 3 the seasonal range based on soil type and depth. This is the data I am looking for but I really need to be able to reference the standard or organization that...
I am working on a project that involved cable calculations for a duct bank. My modeling software defaults to 35 deg C for ambient earth temperature and typically I keep that value so that the design is overly conservative. Usually duct banks I am involved with are less than a hundred feet...
Thanks zumhakr,
I ordered the new version and yes it does correct this by doing away with the "C" value and using bus mass in per centimeters or per inch units rather than meters and feet.
Now I get to spend an afternoon going through the new version to see what all else is different. That...
I have questions about a couple of the equations in IEEE 605-1998 and was hoping someone here might be able to shed a bit of light. In section 11.1 where they calculate bus deflection there seems to be an error in some of the equations. For discussion purposes I will look at equation 14 and...
I am working on a spreadsheet for calculating bus and insulator loads for substations in the US. These calculations are based on IEEE 605-1998 Design Guide for Subsation Rigid-Bus Structures.
I have gotten down into Section 12.1.5 and there is an equation (35) for "total cantilever load acting...
Every naval system I have come across is fully floating like this (MIL-STD-1399 requires it) and I think it is very common in marine applications. I think waross is on the right track about preventing galvanic corrosion but also maintaining system operation in the event of insulation failure...
Thanks ilj,
I have come to about the same conclusion. Something about the generator's construction (magnet strength, location, coil spacing, rotor alignment, etc...) is causing a slight modulation in the output. I was hoping this is something someone might have seen before and could confirm...
I am not sure how many poles are in the generator but I do know it is a high pole count unit. The generator is designed to produce 500 to 1000 Hz, 3 phase Wye power when connected to the diesel prime mover we are using it with. I am not sure what you mean by net frequency. The unit is...
Hi itsmoked,
I have seen electronic ballast for HID lighting but don't think they are much if any more efficient than magnetic for HIDs. Most of what I have seen electronic HID ballast for is some type of special application.
The efficiency gain in fluorescents is a result of the operating...
Hi waross,
Yes it is a little bit of a "different" application. We are testing a standalone PMG being driven by a diesel engine. The voltage and frequency output of the generator in the end application are unregulated and we have a fairly wide tolerance to what we can feed to the next stage...
Hi 2571. I used to work for a ballast manufacturer and thought I should weigh in here.
If you have 277V readily available for lighting use it. There are a couple of different reasons. If 277V is available, your installation costs with 277V will be lower because of reduced wiring and breaker...
Yes. When doing the conducted emissions testing a resistive load of about 15kW was on the generator. To get 400Hz from the generator we had to run the diesel engine at 1000RPM and the engine could only handle about 20kW of load at that speed.
Later we did radiated emissions testing with the...
I have recently been testing EMI on a permanent magnet generator and observed something I can not explain. I am not extremely familiar with PMGs so I thought I might see if any of you guys have seen anything like this before. I was operating the generator to provide 400Hz output and was...
