richanton,
Would you happen to know about what the cost is for that one mile run? Coincidentally, I am looking at options for relocating an existing 1 mile 69-kV overhead circuit, and have no idea about underground costs at that voltage level.
In my case, the 69-kV circuit is insulated at...
jghrist - I realize that the 120kVA was not on system voltage. Was just asking whether it is possible to compare kVA interrupting duties (i.e. 765kV @ 0.1 Amps vs. 220V @ 600 Amps). I know EHV switches are not usually rated to break charging current. But HV switches typically are, but at...
jghrist - That AEP paper was interesting. They calculated the equivalent loop interrupting duty for their 765-kV switches to be 600 Amps with 200 Volt voltage difference across them. They tested them in a lab at this interrupting duty (120 kVA) and noticed that contacts were burning and have...
Problem is that dispatching will refuse to operate the switch unless current is less than 50A, which it is not. I am trying to find some way to prove that it is okay.
I have found an IEEE paper that specifically recommends against switching (with disconnect switch) loop currents at 69-kV and...
I have looked through all the references mentioned (except NEMA), and they seem to be silent when it comes to breaking parallel current with near-zero impedance.
In "ANSI/IEEE Std. C37.100" for the definition of disconnect switch, there is a note that states it must be able to "open or close...
cuky2000 -
Thanks for the info and standard references. I plan to look through them.
stevenal -
Actually the station is not built yet. I am just trying to determine if a plain switch is adequate or if I need to spec something better. Most stations have spare breakers so this issue doesn't...
I am looking for guidelines for the maximum current that a disconnect switch can break when the parallel path has a near-zero impedance (such as in the same station). The voltages I am looking at are 46kV through 161kV.
Specifically I am wanting to open the bypass switch for a breaker after...
windie - Thanks for the advice. That is very similar to what we ended up doing a few months ago. We simplified the logic a little since there were 5 units and to do it right, you have to know how many are turned on.
Thanks everyone for your responses. I am going to look into limiting the exciters on the generators so that they do not consume VARS. They will still be in voltage control mode and will be allowed produce VARS.
peterb,
That is correct and brings me back to my original question: How to coordinate control of the capacitors and generators so that generators do not absorb VARS? I have a couple of ideas (one already mentioned) but am looking for other opinions.
Just in case there is confusion, the capacitors are on the bus that the high side of the GSU's are connected to. There are 4 banks of about 17 MVAR each.
Static capacitors cannot be used for dynamic VARs by themselves, but they can free up dynamic VARs from generators that are outputing...
Yes, these are synchronous generators. Admittedly, this is an unusual case, but there are several situations where it is desirable to have capacitors close to generation. In this case, the generators are fairly small (50 MVA each) and do not produce enough reactive power under certain system...
I have a situation in which we have installed switched capacitors on the bus at a generating plant. There are five generator units and 4 cap banks. Obviously, there is a conflict between the caps and generators since they are controlling the voltage at the same bus. In addition, for stability...
hevd,
Thanks for the detailed response. I must admit that I know very little about steel production, other than that steel plants, even small ones (10-50MW), have caused a lot of power quality problems on our system when connected at 161-kV.
The 500MW plant I mentioned has not been built...
I am interested in information about the latest equipment available to minimize power quality problems (flicker, etc.) associated with arc furnaces at steel mills. Is there equipment available that could correct all PQ problems for a 500MW steel mill connected at 161-kV? And if so, at what...
3 Amps at 415V translated into only about 2.2kW. If this load is going to be served for only a short period of time, why not buy a small generator? For long periods of time a wind/solar system would be attractive.
While in college (about 6 years ago), I worked in the engineering department at a factory that makes electric motors. We made thousands of different models, and often times the only difference between certain models was the lead (or winding) colors. So, in short, I don't think there is a...
As a rule, we use surge arresters on our system in front of all SF6 breakers that are 115-kV and above. Not sure about below 115-kV since I don't deal with that much. I once knew the technical reasons why we use SA's primarily for gas breakers and not oil.
