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73 entries.
Nikhil Singh Nikhil Singh wrote on June 16, 2020 at 9:09 PM
Hello there!

I am a manufacturing engineer at steel plant in Port Talbot (so mostly hands-on guy), Wales. I am designing (well trying!) a 3 winding step up transformer 33kV (P) /132kV (S) , 90MVA. One the 132kV(S) side, I want to create a two windings. S1 will be 99kV rated and S2 will be 33kV rated. During normal operation, the two S1& S2 will work in series. However, during the start-up, I want only 33kVv(S2) winding to work. This way i can get more current into the electric rods to melt the scrap in an electric arc furnace.

Please can anyone suggest how I can rate the windings resistance and reactance values. I would like to send you an excel document and show some calculated values. It would be kind (and great) if anyone can provide some feedback on my calculations and correct them for the three different scenarios with some comments about pros and cons.I really need to understand if the values make any sense as I have no sounding board here.

many thanks in advance!
Admin Reply by: Ver Pangonilo

The best way to do what you are trying to achieve is to have an autotransformer with 33kV pri / 132KV sec.

During start-up, you can connect directly to the 33KV tap of the transformer which means that your are directly across your supply line. After which, you can switch to the 132KV leg of the transformer during normal operation.

The switching scheme for this is much easier than what you are thinking of. series connected secondary winding. The footprint of the autotransformer will be smaller than a two-winding transformer. This makes your equipment much cheaper.

You need to approach a transformer manufacturing company to help you with the transformer design.
Melanie S. Murillo Melanie S. Murillo wrote on February 12, 2020 at 10:01 PM
Hi Sir Ver,

my search for the "FPN or Fine Print Note" led me to your blog..

I didn't expect that the search will lead me to this collection of knowledge..

very nice blog po Sir!
Admin Reply by: Ver Pangonilo
Thank you.
Jon Arellano Jon Arellano wrote on November 28, 2019 at 10:32 AM
Good day Sir,

In Australia, where I can find in AS/NZS 60079 standard the requirement for hazardous area classification report to approve the drawings? We were challenged by the vendor that HAC report is not required on their drawings.

Many thanks,
Admin Reply by: Ver Pangonilo
The standard AS/NZS 60079 is available for purchase at https://bit.ly/33qEDwr
John Richard Amar John Richard Amar wrote on October 28, 2019 at 5:07 PM
Thank you for having this kind of forum website. As one of the newest Registered Electrical Engineer, I am looking for more knowledge from anyone's experience and I think, I might found it here.
Admin Reply by: Ver Pangonilo
Thank you for the compliment
Matt Lockyer Matt Lockyer wrote on September 25, 2019 at 6:18 AM
Thanks for the information regarding access. I have another query if I may - this time asking for "server".
Admin Reply by: Ver Pangonilo
Server is localhost
Paul Torres Paul Torres wrote on September 23, 2019 at 12:31 AM
Hi Sir,
I just want to ask how to solve series open faults.

1. One conductor open fault - Boundary conditions are the same with L-L-G fault. Does it mean that the way to solve one conductor open fault is the same as L-L-G fault?

2. Double conductor open fault - Boundary conditions are the same with L-G fault. Does it mean that the way to solve two conductor open fault is the same as L-G fault?

The source of the formula & conditions which I am referring was posted on below site.

Admin Reply by: Ver Pangonilo
I have discussed open circuit faults in my article Open Circuit Faults, https://pangonilo.com/2010/01/open-circuit-faults.html
Matt Lockyer Matt Lockyer wrote on September 17, 2019 at 9:49 PM
How would you fix or sort an issue to be able to get access back.
Admin Reply by: Ver Pangonilo
Will check and get back asap. All is okay now
Jimmy Leonardo Jimmy Leonardo wrote on August 27, 2019 at 10:22 PM
Defferentiate the P.E.C to N.E.C
Admin Reply by: Ver Pangonilo
PEC is Philippine Electrical Code, applicable only in the Philippines while NEC is National Electrical Code applicable in the United States. However, PEC was based on NEC but dimensions and sizes were converted into metric.
don rainier abesamis don rainier abesamis wrote on August 14, 2019 at 9:23 PM
Hi Sir, student from IIEE TSU Student Council. Just wanna ask kung saan po sa PEC yung plus minus 5% voltage tolerance sa end ng distribution. Thanks!
Admin Reply by: Ver Pangonilo
Your question is a little bit vague but you can check these clauses

For Branch circuits, check FPN 4 under (a)(1)
For Feeders, check FPN 2 under (a) (3)

In design, the voltage tolerance maybe assumed to a certain value which is acceptable to the end user. This are usually stated in specifications and datasheets of electrical equipment. As far as I know (I may be wrong) but PEC does not provide anything about voltage tolerances.
RACQUEL REMORQUE RACQUEL REMORQUE wrote on July 22, 2019 at 3:03 PM
Good day Sir! The water pump motor in our office needs to be rewinded due to very low insulation resistance of the windings. The three-phase motor is 230 V convertible to 460 V. The motor will be used in our new building with 400 V supply voltage. The motor was used at 230 V. Is it possible to just rewind it at 400 V even though it is designed at 460 V? If not, should we just rewind it at 230 V and buy a 400 V step-up, dry-type transfromer or rewind it to 460 V and buy a 400 V step-down transformer? What is the most cost-effective approach Sir? Thank you very much. Hoping for your response on this matter.
Admin Reply by: Ver Pangonilo
Dear Racquel,

As you have not mentioned the size of your water pump motor, rewinding a 230V to 460V will be the most cost-effective. However, ensure that you choose a COMPETENT rewinding contractor to do the job. But, as the operating voltage (400V) is lower than the rated voltage (460V), efficiency will be lower. Long term, I would suggest buying a 400V, 3 phase motor for the application.


John Cox John Cox wrote on June 3, 2019 at 3:39 AM
Hello Sir, I’m soon to have a home built in the Philippines. All the power outlets I have observed there are of two pin variety, however , I’m wondering how I can ensure that in fact all the power outlets have all three supply cables - Live - Neutral and an Earth connection.
Looking forward to reply.
Thank you, and regards,
Mr John Cox
Admin Reply by: Ver Pangonilo
Depending on the location of your house to be built, there power outlet configuration will vary.

In the Meralco franchise area, power will have a 115V-0-115V. In here you can use the NEMA 6-20R outlet. However, if your house is covered by an Electric Cooperative franchise, your power will be supplied at 230V-0 configuration. In this case two pole outlet may be used but you can still use a NEMA 6-20R outlet if you wish.
Bryan Santos Bryan Santos wrote on May 29, 2019 at 5:44 PM
Good day sir, what are the possible reasons for the hard starting of the 3 phase generator?
Admin Reply by: Ver Pangonilo
You need to ask your mechanic about your generator engine.
Samuel Samuel wrote on May 27, 2019 at 10:23 AM
Good day, Engr. Ver, first of all, thank you for the information and tutorials that you have shared, it has been valuable for furthering my EE knowledge. Do you have any additional book recommendations, websites or articles that can help me deepen my understanding of general EE, and power system design and analysis? Thanks!
Admin Reply by: Ver Pangonilo
There are lots of books out there that I could not say which one is best. Just ask Mr Google.

Thanks for the compliments.
Max Max wrote on May 14, 2019 at 7:44 PM
Sir, your site is very informative for practicing electrical engineers in the Philippines. Thank you for all the compilations in your site.

Just a query, Part 2 of the Philippine Electrical Code. I've checked with IIEE but it's unavailable. By any chance, do you have an e-copy? Thank you very much
Admin Reply by: Ver Pangonilo
Thanks for the compliment.

I only have a hard copy of PEC 2.
michael leonard michael leonard wrote on May 10, 2019 at 9:50 PM
I am a plan checker and we have a difference of opinion in my company. My stance is the only one who is allowed to stamp and sign electrical and solar is an electrical engineer or a c-10. can you help me prove my case and help me find where to find that rule or law.
Admin Reply by: Ver Pangonilo
As you have not mentioned your project location, I will not be able to answer your query. Thank you
michael leonard michael leonard wrote on May 10, 2019 at 9:45 PM
I need to know who is allowed to sign electrical and solar plans
Admin Reply by: Ver Pangonilo
Only registered professional engineers with a valid license can sign and seal electrical plans.
maryanne maryanne wrote on May 3, 2019 at 11:47 PM
good day sir! may i know if a Filipino engineer, a civil engineer for example, could work as an engineer in Australia?
Admin Reply by: Ver Pangonilo
If you are a Filipino Engineer and wanted to work in Australia as an Engineer, then your best option is to consult Engineers Australia (https://www.engineersaustralia.org.au/)
Ibrahim Ibrahim wrote on April 9, 2019 at 12:30 PM
I am looking for the excel files of the following:
Creating Coordination Curves with Excel
Time-Current Curves with Excel II
Time-Current Curves with Excel III
Time-Current Curves with Excel IV
Admin Reply by: Ver Pangonilo
The tutorial is very comprehensive that you will be able to recreate the excel files itself. A sample application can be downloaded in the download section of my blog.
lilibeth lilibeth wrote on March 25, 2019 at 11:45 PM
Im a fifth year electrical engineering student from Bulacan, State, University and one of our professor wants us to find a plan, either a commercial or industrial plan with a load rating of 5MVA. Please help me to find a plan. Your response will be greatly appreciated.
Admin Reply by: Ver Pangonilo
Sorry for the late reply. I do not have any industrial plant plans. Thank you
Jade Amolat Jade Amolat wrote on March 9, 2019 at 7:55 PM
Sir, good day po!

Ask ko lang po, anong provision po sa PEC yung nagsstate ng standards for medium voltage electrical distribution? For example, yung size po ng poles na gagamitin saka po mga wire sizes and other things na need po iconsider para po sa design? marami pong salamat and more power po!
Admin Reply by: Ver Pangonilo
Look at PEC Part II. You may find information in there.