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power electronics (11 kv)

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rizwan33

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hey,
how can a we monitor the 11 kv 3-phase AC line on electronic displays(7 segment led's or LCD's).
for example,
if a generation system is generating 11kv 3-phase , how can i translate that 11kv signal fed it to a 7 segment display that will display 11 kv on 7 segment and hex displays.
any help will be appreciated.
 
Anybody doing anything with 11kV should already know the answer to this.

From memory, the creepage distance, in air, at 11kV is about 300mm.

Mike.
 
Below is a data sheet of a panel meter. You can get them LCD or LED. There are many options like 0 to 2V or 0 to 20Volt.

You need to divide the high voltage down!!! I have some 50kV 1g-ohm resistors that are 1 inch in diameter, 10 inches long, one end is connected to HV wire. The entire resistor is in a red insulator. Using a high voltage resistor and a low voltage resistor make a 1000:1 divider to get your 11kv down to 11 votls. Now a simple panel meter will work and measure K-volts.

I can not find data on my resistors. Here are some links to HV resistors.

http://www.caddock.com/Online_catalog/high_voltage/high_voltage.html
http://www.nicrom-electronic.com/Products.htm
**broken link removed**
http://www.token.com.tw/resistor-hv/index.html
http://shop.ebay.com/i.html?_nkw=high+voltage+resistors
https://www.electro-tech-online.com/custompdfs/2011/06/highvoltageresistors.pdf

If you do not understand HV then you are dead!
 

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Something not mentioned that should have been mentioned is the 3 phase configuration. Measuring 3 phase wye is one animal and measuring 3 phase delta is quite another animal. This is especially true if you want to monitor all 3 phases at once. Really bad things can happen in phase to phase measurment sans isolation methods. Since the phase configuration was never posted I tend to agree with Pommie, Not to be hard but if you need to ask about measuring 11 KV you shouldn't be doing it.

Just My Take
Ron
 
Assuming you can find someone qualified to do this, you will need 3 of these in the 15kv class:

https://www.abb.com/product/db0003db004279/c125739900636470c1257199006cbc64.aspx


If installed correctly, this will keep you away from the HV and also give you 3 sets of isolated outputs divorced from Wye or Delta configurations. Most switchgear installations that I have ever seen have one nice meter and an A-B-C phase selector switch.

Whenever the 3-120kv high lines at the steel mill required ANY attention, the utility company was always involved. Even back in those days, death was frowned upon.
 
Why are you guys answering this? He either knows HV or not! If he does then he wouldn't ask the question!! My only conclusion is that you guys don't understand HV either or don't understand why you shouldn't answer questions on it.

Mike.
 
pommie,

sir i know what HV means.
it was just an assignment i am working on.
i came here only for a little help about how to start the assignment.
with due respect,
what do u think of your self?
knowledge is something to share.
the moment i posted a thread on this forum , i was thinking of a bit discussion .
but as the people on this forum like u are not willing to help then i should not post in here.
by the way
thanks for your precious moments you spend on writing these two posts to me.
 
hey,
how can a we monitor the 11 kv 3-phase AC line on electronic displays(7 segment led's or LCD's).
for example,
if a generation system is generating 11kv 3-phase , how can i translate that 11kv signal fed it to a 7 segment display that will display 11 kv on 7 segment and hex displays.
any help will be appreciated.






A complete report on this is to be submitted
now the proper assignment is:
a power plant will run a small industry.
whenever the plant starts a text msg is to be send to the number of manager with the following details:
"The starting voltage.
the initial current.
The time when the plant got started"
The assignment is given to a group of three.
I know the theoretical procedure but dont know exactly what the procedure is practically.
so.
i need help on the practical procedure.
 
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OK, project related stuff. Three phase WYE.

Here is what you can think about as to project and not turn key off the shelf commercial products. Give this link a read. It is only a Fluke 80K-40 HV Probe but the idea here is to note the design and drawing of the probe. Remember, as was pointed out, resistors used in HV divider circuits are not common everyday resistors! Note how the probe based on resistance is designed to work into a specific impedance, that is important.

The reason many members get a little excited is since this thrtead does not show up as a homework or school project and the initial post made no mention of school project they assume (as I also did) that someone just plans to wander into a HV sub station and try to measure 11 KV.

Ron
 
Why are you guys answering this? He either knows HV or not! If he does then he wouldn't ask the question!!
So, your stance infers that some people are born with innate knowledge of HV, and it is only these people who can ever work with HV, everyone else is excluded.

My only conclusion is that you guys don't understand HV either or don't understand why you shouldn't answer questions on it.
I guess that some of us know about, have worked with, and are comfortable with high voltage low current systems, which if you are not carefull will give you a nasty nip and nothing worse.
However, when it comes to something which can deliver sufficient power so that it will not only kill you but fry you to a crisp in an instant, there are less of us with detailed knowledge.

Does this mean that we cannot ask questions about how it should be done? and that the subject should never be taught?

Calm down dear, it is only an internet forum!

JimB
 
So, your stance infers that some people are born with innate knowledge of HV, and it is only these people who can ever work with HV, everyone else is excluded.


I guess that some of us know about, have worked with, and are comfortable with high voltage low current systems, which if you are not carefull will give you a nasty nip and nothing worse.
However, when it comes to something which can deliver sufficient power so that it will not only kill you but fry you to a crisp in an instant, there are less of us with detailed knowledge.

Does this mean that we cannot ask questions about how it should be done? and that the subject should never be taught?

Calm down dear, it is only an internet forum!

JimB

I used to design HV switchgear between 6.6 and 25kV and have seen what those voltages can do to a person. As the title contained "power" I assumed he/she was not talking low current.

The subject should be taught but asking on an internet forum is not the way to learn about it.

On the other hand, I should have realised that someone without the required knowledge would never be allowed to be any where near 11kV.

And, I am calm dear.

I ignored the innate knowledge bit because it was just daft.

Mike.
 
This is off topic a little but what the hell.

I used to design HV switchgear between 6.6 and 25kV and have seen what those voltages can do to a person. As the title contained "power" I assumed he/she was not talking low current.

Currently among my projects is bring in a new sub station to our building. Right now I have a pair of 750 KVA transformers with older 5 KV primaries. That gives us 1500 KVA and we use 480 volt delta. We need more and much more. The new addition sub with bringing in power offered a choice. I can bring in 13.3 KV or 25 KV for a pair of 1500 KVA transformers. If I bring in 25 KV the cost of delivery (power) is less than 13.3. However, I damn near had a coronary when I started looking at the cost of Siemens switch gears for 25 KV. It would take over 35 years before I broke even. Needless to say.... the 13.3 KV is going in. :)

Ron
 
I used to design HV switchgear between 6.6 and 25kV and have seen what those voltages can do to a person. As the title contained "power" I assumed he/she was not talking low current.

The subject should be taught but asking on an internet forum is not the way to learn about it.

On the other hand, I should have realised that someone without the required knowledge would never be allowed to be any where near 11kV.

And, I am calm dear.

I ignored the innate knowledge bit because it was just daft.

Mike.


What the hell r u trying to say.
that u designed a HV switchgear and due to your design u saw people dying??????????


And for your information . i am a student of power subjects.
and this subject is taught very well to us.
 
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Reloadron,
thanks for the attachment.
can we use PT(potential transformers) to step down 11KV to 400-440V(if the option is available)?
And if CT(current transformers)are used for current purpose, can we use A-D convertor(analogue to digital convertor) to convert current signal to digital form for the micro controller? would it be feasible/practical to use this idea?
 
Purely for informational purposes. As was mentioned a project like this outside the classroom is a large project that requires knowledge in several areas. Nothing that can be covered in a single forum. There are commercially available units made for this but for educational purposes we will break things down.

Starting with the mains power delivered to the sub station, in this case 3 phase 11 KV WYE power. We want to measure voltage on all 3 phases as well as current so we start with a "sensor" device for voltage. Yes, the device of choice is the Potential Transformer which is in simple terms no more than a very accurate ratiometric voltage device. For this case 11 KV is considered medium voltage. I suggest you find out the ranges for low, medium and high voltage. Get familiar with potential transformers especially how they are fused and why some use double versus single fuse based on WYE or DELTA applications. Also get familiar with oil and air cooled. Read this link and that is the transformer we will use. Our sub station is indoors! :)

Run to the store and buy 3 of model PTG5-1-110-1442F from the link. Now 0 to 14,400 VAC is equal to 0 to 120 VAC in a 120:1 ratio.

Now we need to do something with our 0 to 120 VAC. While you are at the store buy 3 of these AC Voltage Transducers. You want the 0 to 150 VAC input with a 0 to 5 volt output versions. :)

The scaling is now 0 to 15,000 VAC is 0 to 5 volts DC. Scale it, chart it, record it and do whatever you wish with it. Feed the 0 to 5 volts into a data acquisition device and write the software.

That was a very brief idea of how this is done. There is much, much more to it.

The same would be done for current. The current transformers would be selected for the current at 11 KV.

Again, there is considerably more to all this.

Ron
 
Reloadron,
Thank u very much.
the information was very helpful
I will post u if i find any other difficulty
 
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