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46 entries.
Marlo Lamsen Marlo Lamsen wrote on June 18, 2018 at 1:29 PM:
Dear Engrs,

What is the standard height of switches?

thank you and regards,
Admin Reply by: Ver Pangonilo
The PEC does not have a provision on the mounting height of switches. This means that it will be all up to the end-user whatever is convenient.
Joefrey Tanega Joefrey Tanega wrote on June 13, 2018 at 10:13 PM:
Tanung lang po... pwede po mag tap ng cable sa common busbar ng mvsg (I mean dun talaga mag tap to get power). Sa pagkakaalam ko kasi medyo delikado kasi yun, unang una kaya nga naka enclosed ang busbar compartment is for safety..
Admin Reply by: Ver Pangonilo
It is possible to connect a new feeder on the busbar on the condition that you need to:

  1. Check the fault level on the busbar to ensure that you connect the right protective device and cable

  2. Install a protective device just downstream the busbar

  3. Ensure that you are competent to do the job else ask a competent Electrical practitioner to do the job for you.

TCK TCK wrote on April 5, 2018 at 9:13 AM:
Refer to
SC MVA = KV2 / Z

From IEE regulation Table 4D2B (column 3, 4)
Cable 120mm2:
(mV/A/m)r = 0.33mOhm
(mV/A/m)x = 0.135mOhm
R = (0.33mOhm x 30m) / (Sqrt 3 x 1000 ) = 0.0057 ohm

X = (0.135mOhm x 30m) / (Sqrt 3 x 1000 ) = 0.0023 ohm

Z= Sqrt (R2 + X2)

SC MVA = KV2 / Z = (0.4 x 0.4) / 0.00614 = 26

Should R and X divided by Sqrt (3) for SC MVA calculation please?
Admin Reply by: Ver Pangonilo
Ensure that you are dealing with the correct voltage. Phase voltage is required to solve for the phase cable KVA. For three (3) phase, there are 3 cables so you need to multiply the KVa by 3 to get the total cable KVA.

For single phase, it will be a different calculation.
Jerome Jerome wrote on March 16, 2018 at 6:45 PM:
Hi Good day!

I've been programming some relays, and now i found myself in difficulties understanding my new device. By principle i have an idea how it works but by computation i have some difficulties understanding it. My problem is the Distance Relay . I might understand the principle if i have some illustrations and sample problems with computation.

Hoping for your help and thank you in advance
Admin Reply by: Ver Pangonilo
The best way to understand how to program your distance relay is to refer to the user's manual. To understand the basics of distance relay, you could refer to the following
Ray Ray wrote on March 9, 2018 at 1:32 AM:
Hi Ver! I would like to verify if I have to size the 200A main switch ampere fuse rating of a transformer at 150KVA, 600V primary and 208V primary with a secondary load of 59kW. Do I have to size the fuse base on the transformer primary overload capacity or the feeder load of 59kW? Thanks.
Admin Reply by: Ver Pangonilo
As per provision of the PEC. This is also similar to NEC provision (450.4 Autotransformers 600 Volts, Nominal, or Less). Autotransformers 600 Volts, Nominal, or Less.

(a) Overcurrent Protection. Each autotransformer 600 volts,
nominal, or less shall be protected by an individual overcurrent device
installed in series with each ungrounded input conductor. Such
overcurrent device shall be rated or set at not more than 125 percent of
the rated full-load input current of the autotransformer. Where this
calculation does not correspond to a standard rating of a fuse or
nonadjustable circuit breaker and the rated input current is 9 amperes
or more, the next higher standard rating shall be permitted.

The load need to be protected separately.
Alan Choa Alan Choa wrote on March 1, 2018 at 5:51 PM:
Hi may question lang po. Anu difference ng. 400v/230v system and 460v/230v syatem
Admin Reply by: Ver Pangonilo
A 400/230V system is 3 phase. This is an IEC standard voltage while a 460/230V system is single phase. This is a NEC & PEC standard voltage
jasper jasper wrote on February 20, 2018 at 11:06 PM:
good day po,
Engr. Ver may training pa kayo sa scada? email me po kung meron pa thanks. [email protected]
Admin Reply by: Ver Pangonilo
I am sorry to say, pero wala. Thanks for the enquiry
Dimas Serrano Dimas Serrano wrote on February 15, 2018 at 2:58 AM:
Engr. Ver good morning po. Tanong ko lng po, ilan po ang minimum allowable distance ng poste ng meralco sa property line ay any part ng bahay ko. Salamat po.
Chito Serrano
Admin Reply by: Ver Pangonilo
Chito, kung ang pagbabasehan ay ang PEC, sa aking kaalaman ay walang nakasaad na minimum allowable distance from the property line. Pero meron itong provision on horizontal clearances of wires and cables for other structures is 1.5m (ref. PEC 2 - 2008 Clause Kaya nasa sa iyo na yun kung papayag ka na magtayo ang Meralco ng poste sa property mo.
Ella Ella wrote on December 20, 2017 at 1:16 PM:
Where to find a book?

Philippine Electrical Codes Volume 1

Admin Reply by: Ver Pangonilo
You can buy it from IIEE (
Joefrey Joefrey wrote on November 23, 2017 at 6:50 PM:
tanung lang po
1.0 anu po ang maximum allowable na ampacity sa switchgear (low voltage).
2.0 maximum acb rate is 6300A for low voltage application, anupong susunod na device lets say for 10000A protection, are there any.
maraming salamat po
Admin Reply by: Ver Pangonilo
It is best to consult Standards (IEEE, IEC, etc) for your question. In my designs, I used a maximum of 3200A ACB rating. Larger than that, there will be lots of issues concerning busbar sizes, temperature rise, etc.
shaun shaun wrote on October 30, 2017 at 10:33 PM:
Good day Sir,

I have a problem with VSD failures at one of my sites (a shopping centre). The system consists of an 11kV incomer and many 11kV / 400V distribution transformers.
Power readings indicate an imbalance of voltages on the 11kV incomer terminals.
Where should I start for diagnoses?
Admin Reply by: Ver Pangonilo
The very first thing that you should do is to inform your power provider of the 11KV imbalance. I believe that the culprit is on their side. To protect your VSDs, you should install an undervoltage / single phasing protection relay on the VSD feeder breaker. This protection relay will trip if a voltage imbalance occurs protecting your VSD.
reagan ramos reagan ramos wrote on October 26, 2017 at 2:50 PM:
good day sir,
ask ko lang po if pwede po bang pagsamahin ang set of wires from load and line side sa iisang conduit na RSC?

salamat po
Admin Reply by: Ver Pangonilo
Using good engineering practice, you should not combine line side conductors and load side conductors in a single conduit.
Erwin Directo Erwin Directo wrote on October 19, 2017 at 1:58 PM:
Good day Engr. Ver!

just passed by to say thank you..i found your site few years ago and your site really help a lot..

God bless..
Admin Reply by: Ver Pangonilo
It's good to know you found my site helpful. Thanks for dropping by.
steven haskins steven haskins wrote on August 31, 2017 at 6:05 AM:
I am having trouble correlating motor class insulation and its relation to B rise and F rise. For example, can you have a 65 degree ambient with Class F insulation and meet B rise, why or why not?
Admin Reply by: Ver Pangonilo
In IEC 60034-1:2004, Table 10, the maximum ambient temperature for Class B & F is 40 deg.C. The temperature rise are 130degC (Class B) & 155degC (class F). This means that the 65degC is unacceptable based on this IEC std.
Nems Nems wrote on August 30, 2017 at 4:09 PM:
Sir Ver
Good day, im working in hospital facility, voltages in our distribution line are L1N=115v, L2N=120v, and L3N=220v, but the line to line voltage is 230v, QUESTION-what do you think is the problem. any suggestion or recommendation please. thanks
Admin Reply by: Ver Pangonilo
I reckon that your system is Wye ungrounded with unbalance load. Check the current of each line to verify the load of each line. To solve this problem, ensure that you have asolidly grounded neutral.
Alex Bogias Alex Bogias wrote on July 26, 2017 at 1:28 AM:
Hi Ver,

The book you have titled "Introduction to Power System Protection" is not the "Practical Power Systems Protection".

I suspect its from people from Schweitzer Engineering Laboratory (SEL) but I simply can't find it.

If you have any ideas please let me know.

Thanks and regards
Admin Reply by: Ver Pangonilo
In my recollection, I believe that this book was given to us as a reference in one of the training I attended but I could not remember which one.
Pablo Jabajab Jr Pablo Jabajab Jr wrote on July 13, 2017 at 12:28 AM:
Greetings Ver!

It’s my pleasure to have your contact.

I have query regarding the time-curve characteristics of the circuit breakers.

I prepared a circuit breaker coordination considering LSIG trip unit protection from downstream to upstream.

How to prepare time current curve in excel format? Is there available software for this particular requirement? Please advise.
Admin Reply by: Ver Pangonilo
Search my site and, you will see tutorials on how to do time current curve in excel.
Alex Bogias Alex Bogias wrote on May 26, 2017 at 10:29 PM:
Hi Ver,

The book titled "Introduction to Power System Protection" is of interest to me and I would like to purchase it but I believe that is NOT its title.

Do you by any chance know its official title?

Thanks and regards
Admin Reply by: Ver Pangonilo
Try this book
Practical Power Systems Protection
Author: Les Hewitson
Ravi Prakash Ravi Prakash wrote on May 19, 2017 at 2:27 AM:
Sir, I am sorry for not giving all detail about the design of transformer. The detail of transformer are as:
A 2 winding 3 phase transformer of 33kV/440V, 2MVA has short circuit voltage is 6.5%.I have to put the right value of short circuit power in software so that transformer can operate with minimum loss.
I have applied common approach but not getting right value. Please let me know some approach.
Admin Reply by: Ver Pangonilo
Are you trying to design a transformer, want to create a transformer specification or doing a fault analysis using the transformer you mentioned? What are you trying to achieve?
Ravi Prakash Ravi Prakash wrote on May 18, 2017 at 4:26 AM:
I have to know about design of two winding transformer.
SC Voltage
Admin Reply by: Ver Pangonilo
With such a little detail, I am sorry but I could not help you.

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