When it comes to Electrical..

Voltage is always about insulation and Current is always about ratings...

Which One is more dangerous: Voltage or Current?

Here is the analogy:-

" Imagine yourself fall down from a very high level of waterfall land then carried away by a very rapid water flows" aren't both situation are dangerous?

The same case as voltage and current. Voltage is dangerous when it is high coz it generates potential. In an open space you cannot go to near to a high voltage installation as you could get a flash over.

As for current even though it is low, it is still dangerous if you come in contact with the conductor coz you will become a pathway for the current to flow through to the earth.

Pencawang Pembahagian

Definisi:

Pencawang Pembahagian adalah penempatan dan pemasangan beberapa perkakasan atau radas elektrik seperti

1. pensuisan voltan tinggi

2. pengubah 3 fasa

3. kabel voltan tinggi

4. kabel voltan rendah dan

5. pengagihan voltan rendah, pengecas bateri dll

yang digunakan utk mengarahkan pengaliran tenaga elektrik dalam sistem kuasa dan memastikan keselamatan sistem dengan menggunakan satu skim perlindunga.

Kategori Pencawang Pembahagian:

1. Pencawang Masuk Utama: tempat dimana voltan tinggi direndahkan ke voltan pembahagian

2. Pencawang Pembahagian Utama: tempat dimanak voltan tinggi pembahagian 33kV atau 22kV diturunkan kepada rangkaian 11kV

3. Stesen Suis Utama: tempat dimana pengumpulan dan pemasangan voltan tinggi 33kV, 22kV atau 11kV sahaja dan tanpa alatubah

4. Pencawang Elektrik: tempat dimana voltan tinggi pembahagian 33kV/22kV/11kV diturunkan ke voltan yang lebih rendah iaitu 433 Volt bagi membekalkan tenaga elektrik ke pengguna.

5 jenis PE

1. Pencawang Berbangunan - biasanya di kawasan perumahan atau kilang

2. Pencawang Luar Bangunan berpagar - biasanya di kawasan kilang atau luar bandar

3. Pencawang Atas Tiang - biasanya untuk kawasan luar bandardimana beban setempat tdk terlalu tinggi

4. Pencawang Padat -

5. Pencawang Dalam Tanah

Komponen Asas Pencawang Elektrik

1. Kepungan - Bangunan, Pagar, Kiosk Tertutup Logam atau Tiang

2. Alat Pensuisan Voltan Tinggi & Voltan rendah - Pemutus Litar, RMU, Isolator, LV Dist Board, Fuse

3. ALatubah - 3 Fasa

4. Kabel - Voltan tinggi & Rendah

5. Sistem Perlindunga - Relay & Fuse

6. Sistem Pembumian - Letrod bumi, Penangkap Kilat

7. ALat Pemadam Api - CO2 dry powder

8. Cap Bank - memperbaiki faktor kuasa

9. DC system - 110V for 33kV and 30V for 11kV

10. Arahan pertolongan cemas

11. Tikar Getah - for indoor substation



Peralatan Utama Pencawang Elektrik

1. Alatsuis - circuit breaker or RMU

2. Alatubah - to step down voltage

3. LV Dist Board - mempunyai busbar, link, fius dan juga alat pengukuran. Dua kategori: feeder pillar dan LV Board

Perbezaan antara Circuit breaker dan RMU adalah CB mempunyai sistem perlindungan pada outgoing feeder yang menggunakan DC. Manakala, RMU hanya pada litar Tee Off untuk alatubah sahaja yang mempunyai sistem perlindungan menggunakan fius voltan tinggi tanpa memerlukan DC.

Sistem Sokongan Pencawang Elektrik

1. Sistem Pembumian

2. Sistem Bekalan arus terus (DC)

Carta Aliran Menduduki Peperiksaan Perakuan Kekompetenan Jurutera Elektrik Kompeten

Carta Aliran Menduduki Peperiksaan Perakuan Kekompetenan Jurutera Elektrik Kompeten

Are you a Competent Person??

Are you a Competent Person?? what would you think if somebody ask you this question? what do you understand with the word competent? Yess...anything can be interpreted right.. Anyway, I'm just asking coz at the moment I'm in d midst of applying for competent engineer interview and examination. This was the question that i asked myself: Am I competent enough to go for the interview? After a few moments of thoughts I finally say Yes. haha yes I did say that.

Think about this...competent is defined as having the necessary ability, knowledge or skill to do something successfully. And you can be considered competent if have enough experience the field where you have been working on. so In short, I'm eligible to go for the competency interview, since i have years of working experience + knowledge in this field.

So friends, if you think you are competent enough already to go for the next level, never hesitate to go forward. Just ask your self a simple question and answer it honestly. you will find the answer.

till then...bla bla bla.. lol (just want to update this site since it was abandoned sometime ago.. ^^

Why Tangent Delta Test is important?

Electrical properties of the insulating system change due to age and continuous electrical street. The principal contributor to the unexpected breakdown of the high voltage equipment is the insulation failure.

As compared to the magnetic, conducting & insulating materials which form the basics of any electrical equipment, the insulating material is more prone to service stresses like thermal stress, electrical stress, mechanicals stress, environment stress etc.

By measuring the electrical properties such as capacitance and Tan-Delta regularly on periodical basis, it is possible to ensure the operational unexpected breakdown.

Dissipation factor (Tan-Delta) is one of the most powerful off-line nondestructive diagnostic tool to monitor the condition of solid insulation of various high voltage equipment. Capacitance and Tan-Delta values obtained on new insulation are treated as benchmark readings. Then by measuring and comparing the periodical readings of the capacitance and Tan-Delta of the insulating material with the benchmark readings, one can know the rate of deterioration of the health of the insulation.

Knowing the rate of deterioration, we can be able to Predict the future unexpected breakdown of the insulation of HV equipment. Plan the maintenance schedule. Repair the insulation before actual flashover, saving high cost of replacement of material which will reduce the inventory well as delay in procurement at the last minute.

After repair, quality of insulation can be checked before returning the equipment to service. When to check capacitance & Tan-Delta During manufacturing process preferably at each stage. In service & will be depend on rate of change of Tan-Delta Vs Voltage Vs Time (Month/Year).

Frequency of testing depends on history of past failures on same machine. Frequency of testing depends on environmental conditions. More humidity, temperature, pollution would require frequency measurement of Tan-Delta.

How to Calculate the Short Circuit Current rating Capacity for Cables??

Just recently i learnt something new..the basic concept of engineering..once again almost forgotten until I was asked this question..."Do you know how to calculate short circuit current rating capacity for cables?", for a moment i stop and think.. i didnt know what is the answer...
*(^-^)* - (embarrased)

From there, i didn't stop but I started checking through my text books, surf internets, discuss with my collegues who in charge with planning, protection schemes and etc..

I finally found the answer..it is just a very simple formula..

Isc = VLN/Sqr. Z^2 ; VLN = Line to Neutral Voltage
Z = Positive sequence impedance of the cable (u can get from the
technical particular of the cable)

Very simple right...wait a minute, don't be mistaken with the other formula where u need to add in the impedance of the transformerr and generators. U need this data when u want to know what would be the the short circuit current when fault occurs on any part of the system..