Thanks for the 300.1(B) suggesstion. I think we fall outside of that, however.
I have found an interesting Article 725 that talks about Class 1, 2, and 3 remote control, signaling, and power limited circuits. Class 2 and 3 circuits are exempt from a lot of Article 300. Anyone ever "use" this...
I work for a small machine builder. We just got hit for mixing wiring and pneumatic tubing in the same Nema 1 raceway. This has never come up before in the 10 years or so of this company...
What are peoples opinion on NEC 300.8 that says not to? Is my assumption that it gets done all the...
MikeHalloran, you just described my EE senior design project! I made 3 receivers, collected delay data from them and triangulated a position. The idea was to locate someone with a "panic buzzer" using sensors on the blue light emergency call poles in many campuses.
The implementaiton of...
The DC controllers do have some sort of current limiting, though nothing I can see that would satisfy NEC. I am starting to wonder if the motors are, like DRWeig suggested, impedance protected or the like. I'm chasing down the manufacturer now to find out for sure. Thanks for your...
I am integrating process equipment where a 3rd party is suppling some of the equipment incorporating a few DC controlled motors, and their control boards. I am responsible for documentating the circuits they are on, starting at the load center.
It seems that this supplier is IEC EN61010-1...
A ground and a neutral are at nearly the same potential, but they serve different purposes. They only place the two can be connected is at the main panel (and must be connected).
The difference between them is that a neutral is the wire that carries the current from the hot back to the main...
rbulsara,
yeah, I figured...Going through the exercise you mentioned I see that the Line Currents work out to be the same either way. It's basically a Voltage/Current mirror image of each other.
I also found the table 430.52(C) listing, like you said 250% max short circuit protection. It...
Thanks rbulsara, for adding into the calculations the power factor and efficiency. That is helpful to see how NEC came up with the numbers they did.
I may not have made it clear that the power source for my motors is a 480 delta configuration, reguardless of the motor windings as you pointed...
Thanks!
OK, so the current seen by the wire (line current) is multiplied by the sqrt of 3 to phase current to give me 4.2 Amps, that makes sense now. Why do you think NEC would list 7.6 Amps? I'll take a guess...because the motor rating is for output power and doesn't take into account other...
I am trying to size a circuit breaker for a 3 phase motor given it's power consumption. Note that I am not sizing a thermal overload.
Here goes:
Working with 480 VAC Delta and a motor rated at 3.5kW.
If the total power of the motor is 3500 Watts, than each winding is supplying 1/3 of that =...
I'm ready to pull my hair out here. I'm a new user to autocad and can't figure out why my dimensions are different in paperspace than in model space. What am I missing here. Where do I set a scale factor and how do I make it 1:1?
Please help
Jason Bender
I finally got in contact with my client and have been informed that I am in fact working with an ungrounded delta system. Why would somebody in his position glaze over that fact like it was no big deal! This is a serious design consideration, and all he tells me is it's "simple 3-wire" wtf...
That does make some sense, Dave, thanks.
My application is to power a dozen or so motors, most all of them being controlled by VFD's. Most of these motors are small (fractional horsepower). Where I get uneasy is not so much whether or not the 480 3Ph. comes from a Delta or Wye but whether...
So from the sounds of it, his answer of "simple 3-wire" still leaves some ambiguity as to the type of power that is available.
Like you said, stevenal, it could be ungrounded or grounded delta...this I can see. How could it be from a grounded wye? by just neglecting the common?
If it is in...
