Pole Lights Calculation

[mivey]

The point mentioned in serial no.2 of the said reference does not specifically state that it is applicable to indoor transformer only. So please don't mislead.

You have not provided a good link. Information gained from available snippets shows the heading to be:

Subject:- Provision of Transformer Substation & Engine Alternator in Telecom Buildings - ISSUE of Guidelines.

There is no misleading on my part, just trying to piece together the garbled mess you throw out.

Since we have addressed harmonics mitigation using k-factor transformers, what other adverse environmental conditions are you considering?

If the 85% is for a 1.18 factor-k for harmonics (about equivalent to a k-factor of 9), BSNL should be using k-factor transformers instead of de-rating standard transformers. Maybe inefficient decisions like that is why they have been bleeding money for years and are considered a sinking ship in the telecom sector.

 

[Sahib]

I used the information at my disposal. The OP provided very little. I drew upon my many years of experience to provide an educated respond with the given data. You on the other hand seem to have very limited experience with this and are just swinging wild. Perhaps you should learn what you are talking about before you talk about it.

Your educated guess is incomplete: you failed to take into account the effect of constant power light sources on the rating of the transformer. You did not acknowledge the allowance to be made in the transformer(80% rating) to meet such contingency as suggested by me.

Still complete nonsense.

Really?i

20% was your number, not mine. Your lack of experience made you throw that number out there and now you are trying to find a way to justify a statement made in ignorance. Just admit you stepped beyond the scope of your experience and let it go at that.

It is not a matter of lack of experience on either side. The 20% number stems from lack of data from the OP.

 

[Sahib]

You have not provided a good link. Information gained from available snippets shows the heading to be:
If so, go to
http://www.electrical.bsnl.co.in/
and click on the electromechanical_book under the heading 'Technical'

There is no misleading on my part, just trying to piece together the garbled mess you throw out.

Not agreeable,objectively speaking.

Since we have addressed harmonics mitigation using k-factor transformers, what other adverse environmental conditions are you considering?
If the 85% is for a 1.18 factor-k for harmonics (about equivalent to a k-factor of 9), BSNL should be using k-factor transformers instead of de-rating standard transformers.

Harmonics do not figure as an adverse environmental condition. See the definition of 'environment' here http://www.thefreedictionary.com/environment So it pertains to temperature, air density and as such.

Maybe inefficient decisions like that is why they have been bleeding money for years and are considered a sinking ship in the telecom sector.

I could quote from another book about 85% factor written by an independent consultant with over 44 years experience who served in various organizations but don't want because you would then say he was expelled from such organizations for having such bad ideas.

 

[weressl]

There is no misleading on my part, just trying to piece together the garbled mess you throw out.

Obfuscationhmy: and mongoose talk is obviously what our friend tries to pass on as engineering judgement from the mysterious continent of India. We are just so below his superior knowledge and intellect that it is futile to challenge.

 

[weressl]

Indian student blog

Indian student blog

You may want to know about Indian culture - from an Indian student - compared to US: http://www.businessinsider.com/the-weirdest-things-about-america-2013-8


Especialy:
"Everyone is highly private about their accomplishments and failures. Someone's performance in any field is their performance alone. This is different compared to India where people flaunt their riches and share their accomplishments with everybody else."

"Strong ethics ? everyone has a lot of integrity. If someone cannot submit their completed assignment in time, they will turn in the assignment incomplete rather than asking for answers at the last minute. People take pride in their hard work and usually do not cheat. This is different from students from India and China as well as back home in India, where everyone collaborates to the extent that it can be categorized as cheating."

 

[Sahib]

If you cannot provide valid counter argument, stay back and observe how the argument develops.
Let both myths and facts, knowledge and ignorance, strengths and weaknesses be present in the argument. In that way let it attract other members also to contribute. That is a way to develop intimacy and to shed your messianic complex: a feeling of 'better' person than others thereby insulating oneself from full interaction with other equally brillant minds.

 

[weressl]

If you cannot provide valid counter argument, stay back and observe how the argument develops.
Let both myths and facts, knowledge and ignorance, strengths and weaknesses be present in the argument. In that way let it attract other members also to contribute. That is a way to develop intimacy:jawdrop: and to shed your messianic complex:rotflmao:: a feeling of 'better' person than others :?(English please) thereby insulating oneself from full interaction with other equally brillant minds.

Do you listen to yourself? Or are you looking in the mirror when you write such 'psychological profiling' of people whom you don't know?!

It is quite entertaining, bordering on hilarity.

 

[Sahib]

You bent on personal attacks; no technical arguments.

 

[kingpb]

If you cannot provide valid counter argument, stay back and observe how the argument develops.
Let both myths and facts, knowledge and ignorance, strengths and weaknesses be present in the argument. In that way let it attract other members also to contribute. That is a way to develop intimacy and to shed your messianic complex: a feeling of 'better' person than others thereby insulating oneself from full interaction with other equally brillant minds.

I'm sorry, but the inane comments such as quoted above, do nothing to attract other members; quite conversely in fact.

Perhaps it would be most prudent for you sir, to ponder upon a couple apropo quotes by truly brilliant minds:

"It is better to keep your mouth closed and let people think you are a fool than to open it and remove all doubt." - Mark Twain


"Ignorance speaks loudly, so as to be heard; but its volume proves reason to doubt every word." - Wes Fessler


But certainly, not on my account anyway, should you feel obligated to relinquish the obfuscated approach you provide. I personally take delight in the buffoonery.

 

[weressl]

You bent on personal attacks; no technical arguments.

There is no technical basis to conduct a discussion with you, you're so out on left field that there is simply just no connect.

What do you consider your post, if not personal attack?

"If you cannot provide valid counter argument, stay back and observe how the argument develops.
Let both myths and facts, knowledge and ignorance, strengths and weaknesses be present in the argument. In that way let it attract other members also to contribute. That is a way to develop intimacy and to shed your messianic complex: a feeling of 'better' person than others thereby insulating oneself from full interaction with other equally brillant minds."

 

[Sahib]

kingpb & weresl:
I repeat

If you cannot provide valid counter argument, stay back and observe how the argument develops.

Give way to some young minds in the forum to give further constructive technical comments.

 

[weressl]

kingpb & weresl:
I repeat

Give way to some young minds in the forum to give further constructive technical comments.

Sahib,

If you can not provide sound technically valid points stand back and just stay silent with your misleading comments.

 

[Sahib]

Sahib,

If you can not provide sound technically valid points stand back and just stay silent with your misleading comments.

I already gave my technical replies to mivey at my posts #82&83. Why can't you just continue with it, pointwise?

 

[mgookin]

I already gave my technical replies to mivey at my posts #82&83. Why can't you just continue with it, pointwise?

Sahib: This is not the only thread where you are the outcast. Mr. Holt provides this invaluable venue for our benefit in doing our jobs and everyone is expected to conduct themselves in a professional manner. You are ruining it for everyone. Chill out. Let it go. Take a rest on your magic carpet.

 

[Dennis Alwon]

Okay guys-- lets keep it peaceful. Enough of the constant bantering-- thank you

 

[mivey]

Your educated guess is incomplete: you failed to take into account the effect of constant power light sources on the rating of the transformer.

What constant light source do you have for 400 or 480 volt systems. Even so, the 8 poles I suggested had a lot of slop for a preliminary estimate. The OP needs to have better data for a bid or actual design. I provided some examples of how he might make the calculations with better data.

You did not acknowledge the allowance to be made in the transformer(80% rating) to meet such contingency as suggested by me.

You have not provided any valid significant contingency that had not been accounted for. If you are suggesting using the watt load and using an 80% figure that is normally used for a growth factor to come up with a volt-ampere supply need then you are nuts. It is better to model the loading as accurately as you can rather than use an unrelated percentage to swing away with.

Really?i

Yes, really. You.

It is not a matter of lack of experience on either side. The 20% number stems from lack of data from the OP.

Then use appropriate factors for the different pieces and try to make a better estimate rather than using some generic unrelated percentage that you heard about once from a friend's brother's cousin's next door neighbor who overheard that number at a dinner party but really wasn't sure what the conversation was about.

 

[mivey]

If so, go to
http://www.electrical.bsnl.co.in/
and click on the electromechanical_book under the heading 'Technical'

That link does not work for me. Maybe it is an internal link at your work but it does not work across the pond as far as I can tell.

Not agreeable,objectively speaking.

Then something is getting lost in the translation.

Harmonics do not figure as an adverse environmental condition. See the definition of 'environment' here http://www.thefreedictionary.com/environment So it pertains to temperature, air density and as such.

We also have "harmonic environments". I was trying to find some way to justify the number you gave. The only thing that came to mind at first was an indoor substation that might be subject to ventilation problems and elevated temperatures. Since you nixed that idea, I was looking for other possibilities.

If you are having to derate the transformer that much for the environment, you might want to consider having one designed to fit the environment. I could understand stretching it to maybe 90% but much above that and I would think you really need to get a better transformer.

I could quote from another book about 85% factor written by an independent consultant with over 44 years experience who served in various organizations but don't want because you would then say he was expelled from such organizations for having such bad ideas.

Well since his 85% does not agree with your 80%, I'm going to dismiss him outright because he obviously does not know what he is talking about.

 

[mivey]

We are just so below his superior knowledge and intellect that it is futile to challenge.

He might be a Borg in disguise.

 

[Sahib]

What constant light source do you have for 400 or 480 volt systems. Even so, the 8 poles I suggested had a lot of slop for a preliminary estimate. The OP needs to have better data for a bid or actual design. I provided some examples of how he might make the calculations with better data.

The problem is you did not give any clue as how to proceed when the pole light KVA exactly divides the transformer KVA. Use of constant power light sources in such cases necessitate increasing the rating of the transformer. Anticipating this I proposed 80% loading.

You have not provided any valid significant contingency that had not been accounted for. If you are suggesting using the watt load and using an 80% figure that is normally used for a growth factor to come up with a volt-ampere supply need then you are nuts. It is better to model the loading as accurately as you can rather than use an unrelated percentage to swing away with.

The contingency arose due to lack of data from the OP. That the OP has not mentioned whether he is going to use constant power light sources or not is one such comtigency.

Yes, really. You.

Please put with relevant figures then.

Then use appropriate factors for the different pieces and try to make a better estimate rather than using some generic unrelated percentage that you heard about once from a friend's brother's cousin's next door neighbor who overheard that number at a dinner party but really wasn't sure what the conversation was about.

I again repeat that you yourself better use such percentage in your estimation when there is a lack of data to do accurate calculation. But do not confuse with 85% factor mentioned in the BSNL's guidelines and elsewhere which is for adverse conditions the transformer likely to operate under to be taken into account even for exact calculations.

 

[kingpb]

Dear member,
i have a project based on a highway pole lights.
so now i have to calculate how many poles will be on one transformer,details are ....Trnsrfmr rating is 200 kVA, Lamp rating is 1.5 kW, and we have to fix 12 no of lamps in one pole.so one pole rating is 18 kW.so how many poles will be on one transformer.?

In my experience, which spans 27+ years, my estimate would be to assume new fixtures with a high power factor of 0.9, input watts on a metal halide 1500W lamp ballast is approx, 1605W (according to Standard Lighting cut sheet). That's what my specification would say as engineer of record.

Therefore, fixing 12 lamps to each pole, as required by Owner, is 19.26kW, or 21.4KVA per pole; which equates to 9.34 poles per transformer. Since you can't have a partial pole, means 9 poles max. per transformer. Which Mivey answered in post #5.

9 x 21.4kVA = 193KVA, gives me 7kVA spare, or about 4% to cover losses.

KVA is KVA, voltage has no consequence on the question.

You can throw in a whole bunch of manusha to try and convolute the matter but that would be my design. The rest of the 10 pages of arguing over reading between the lines is overkill which BTW shot the budget, pissed off the client, and gets you fired from the project.

Nothing to see here people, move along.