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Industrial electricity
Low power factor with everything turned off
2
hace 5 años
hace 5 años
Regards...
I write to you because I have problems with the power factor, the problem is that the factor that shows me on the bill is 0.3 ... as the fine is an average of what was consumed in the billing period, I asked the supplier company that will send me the energy consumption information, (kwh, kw and kvar) during the last period.
When the machines in the company worked (from 8am to 6pm), the factor remains above 0.92. in the evenings and weekends it goes to 0.3.
Investigate that you could lower the factor and perform a final test, with the main switch of the transformer output down and all turned off, it indicates a consumption of 0.4 power factor. I am not consuming electricity (Kw).
My question is: could the 13kV / 380V traffic be damaged and somehow consume Kvar? Or could the measuring path that is found before the feed that feeds the company be damaged (the power meter of the supplying company is connected)?
Thank you very much for your support...
Note: at night there is only one alarm on, 4 mixed light bulbs and a server (total consumption of less than 10 Amps)
Note 2: The meter has already been verified by the company.
Note 3: An automatic capacitor bank is installed.
Note 4: I leave a link of the very simple diagram of the installation with which I have problems:
https://pbs.twimg.com/media/DQyllR_UIAEMd4Z.jpg
44.317
hace 5 años
hace 5 años
Jehan
From what you say that with the machines running they had a FP of 0.92, I can conclude that they have connected FP capacitors, which were not disconnected when the machines stopped.
By leaving the capacitor bank connected, without consumption, a low FP is equal but now instead of being inductive it is capacitive.
You have to disconnect the capacitor bank.
2
hace 5 años
Hi Ennio !!!! ...
Thanks for your prompt response!!!!...
But no, there are no connected capacitors ... since the disconnection that I indicated in the first question of there is fed into the capacitor bank ... that is to say that the secondary of the entire company's traffic is disconnected.
My question is that if the main or measurement (of the energy company) could be damaged and indicate a low power factor.
44.317
hace 5 años
A doubt, the meter is connected before the transformer or after the transformer .. ??? It is necessary to know this, since a transformer in vacuum or with very little load, connected to the network, has very low power factor.
2
hace 5 años
Ennio ... thanks again !!!
I leave you a link of the very simple diagram of the installation with which I have problems:
https://pbs.twimg.com/media/DQyllR_UIAEMd4Z.jpg
As additional information, the traffic is about 500KVA, the load I handle is 250A when all the machines are running, the average most used load is 60A .. and in the nights as I mentioned before, only lights and server.
Thank you in advance for your answer!!!
44.317
hace 5 años
Regarding the queries, it should be a query by topic, like this one. If you have not solved the problem, you should wait for other colleagues to respond and not ask another question on the same topic.
From the problem posed, the compact of measurements, is taken before the transformer, so a new compensation calculation must be made when everything is disconnected, unless the FP correction bank is automatic.
Discuss what the capacitor bank looks like.
2
hace 5 años
Thanks Ennio ... I will take into account the comment regarding the queries ...
Returning to the topic of the consultation:
The capacitor bank is automatic, when I disconnect everything from the distribution board, absolutely everything is de-energized and the meter of the supply company indicates a factor of 0.09.
That's why my doubt: in other companies, having even more machines, when disconnecting all the FP is 1.
44.317
hace 5 años
If the bank is connected, what you mentioned is correct, that the FP should be as close to 1.
Check if the indicated value with everything disconnected says LEAD (advance) or LAG (delay).
Being capacitive will mark LEAD and being inductive, will mark LAG.
44.317
hace 5 años
Since there is a phase without load, the bank may not work.
From what you say, an individual correction should be made only to the 2 phases of what is connected.
2
hace 5 años
That's right...
But my question still continues:
Why do I have a bad power factor with everything turned off?
what should i do? what steps should i follow?
I have called supposed specialists and the only thing they want to sell me is a new capacitor bank ... but my problem is not the capacitor bank, the problem is when I have nothing connected ... I take everything out of service to the bank ...
2
hace 5 años
Hi Ennio, the issue is not that the power factor controller is damaged, poorly calibrated or poorly designed, the problem is that with a very low load on the transformer, it maintains a power factor of 0.3 ... and with all disconnected 0,09 ... what could be the reasons? (This measurement is in the energy meter of the supplier (enel - Chile)
44.317
hace 5 años
As I mentioned before, the transformer has very bad FP when it is empty. This happens when you disconnect everything from the distribution board.
Apart from this, there is the problem that with a low load, you have a phase without load, so the bank does not correct since that phase would practically remain with FP 0 (zero).
This is because the relationship between reactive power and active power is very high. Not so in operation that as the active power increases, the ratio decreases.
My opinion is that you must leave the distribution panel connected, so that the capacitor bank is energized.
44.317
hace 5 años
And apart make a correction to the 2 phases that remain with load for the days that the plant does not work.
Another possibility is that they distribute the loads in the phases, so that the one that is left without load takes charge and so the bank can act.
234
hace 5 años
hace 5 años
Hi. You have high measurement, so what consumes your transformer in vacuum is what distorts the reagent reading, your capacitor bank is unable to do something about it because it is low, so do not know what is consuming your transformer There is not much you can do, negotiate with your supplier for a "low" measurement. I do not recommend putting capacitors because you run the risk of resonating and exploiting everything !!! Regards
2
hace 5 años
Thanks Yonaldopc !!!
From the little I remember of transformers, the greatest losses are found when the secondary is empty, so I think that the power factor is due to this added to what you indicated ... can this be the theoretical basis that Can I enter into a conversation with the company that supplies the electric service?
234
hace 5 años
No. How to insert a new response to the colleague, but in some countries, it is possible to hire several readings in the meter meter, I have seen up to three rates (day, afternoon / night and peak). You could negotiate with your administrator because you do not have how to control the reading by discharge, so you may not be able to consider what was consumed during off hours. I don't know what country you are in or what is regulated there ... Good luck
2
hace 5 años
Thanks YonaldoPc ... indeed the problem is that the traffic is used at a capacity of less than 15% of its nominal power ...
The most suitable solution is to calculate the invoice of how much KVAR I need to compensate, place it in the secondary of the traffic without it being controlled or measured by the capacitor bank.
2
hace 5 años
Thanks to the comments of this Post, place a capacitor calculated to correct the FP of the traffic (which I remind you that it works at less than 10% of its capacity). This 30KVR capacitor is placed in the secondary of the transformer before the capacitor bank, so that it corrects the power factor produced by the transformer and the capacitor bank is responsible for correcting any variation of the additional inductance that can be charged in the system .
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