AutoCAD-Plot Setup & Publish (Lesson Learn)

 Harini nak share sikit berkenaan AutoCAD. cara nak buat plot setup & publish. step ni amat penting sekiranya kita perlu print menggunakan AutoCAD yang bilangan sheet yang banyak. Ambil masa yang lama kalau nak print satu persatu dalam model. 

Langkah ni, amat menjimatkan masa samada print terus ke printer ataupun print convert ke PDF. Selamat mencuba

HV Short Circuit Calculation

 Bagaimana nak kira Short Circuit Calculation untuk High Voltage? penulisan ini mungkin akan diperbaiki dari masa ke semasa. harap ada yang menegur jika salah.

Fault dari source akan melalui semua peralatan (contohnya Transformer, Kabel) kepada fault point. Value fault / short circuit adalah bergantung kepada value Voltage dan Impedance dari source hingga ke fault Point. Lagi tinggi impedance, lagi rendah fault/ short circuit current rating. sebaliknya kalau rendah impedance, maka akan tinggi fault value. 

Perbezaan unit antara Fault Level dengan Short circuit current untuk kita tahu adalah seperti berikut:-

    Fault level: unit = MVA

    Short circuit current: unit = kA

Contoh SLD, menunjukan kedudukan Fault 1, Fault 2, Fault 3

Step 1: Calculate Impedance untuk Generator, Transformer, Cable

Step 2: Calculated Fault di lokasi terbabit. Value ini adalah value minimum fault. 3 phase & 1 phase. 

sekian: 

updated pada 10.03.2021

HV MV Cable carrying capacity

HV, MV cable carrying capacity:-

1.132kV 800mmsq, 1circuit=110MW*,2circuit=220MW* (copper)

2.33kV 630mmsq=27MW* (aluminium)

2a. 33kV 630mmsq=34MW*(copper)

3.11kV 800mmsq=12MW* (aluminium)

4.11kV 500mmsq=8MW* (aluminium)

5.11kV 240mmsq=5MW* (aluminium)

6.11kV 150mmsq=4MW* (aluminium)

*Mega Watt (MW) indicated as for reference. actual value need to refer cable manufacturer details.

How to determine Substation Voltage Drop & Short Circuit using Per Unit Calculation

Per unit system as a basis for calculation

Select 100MVA Base

All impedance, voltage and currents  & power flows are converted to Per unit

Express all Quantities in Dimensionless Units

Lets Start the calculation:-

Step No.1:-

Step No.2:-

Step No.3:-

 Step No.4:-

 Step No.5:-

 Step No.6:-

  calculate for 33kV system

 calculate for 11kV system

Single Line Diagram

Voltage Drop

Whatever or how perfect the conductivity of a cable, we will still faced a voltage drop problem caused by natural characteristics, which the impedance exist along the cable when convey currents. Based on certain resource, the voltage drop from the origin source must not be more than 4% of the supply.

Consequently, if we need to deliver supply to long distance, voltage drop calculation must be considered. This will help us to choose the appropriate cable’s size for our design, and to avoid the voltage drop more than 4%.

For this topic, I have approached formulas for the appropriate calculation on voltage drop. What I can conclude from this study is shown below:

VOLTAGE DROP

• Cause by impedance exist in cable
• Can be ignored if the cable length is short

Maximum voltage drop tolerate is 4%:

(a)    For three phase = 415 x 0.04 = 16.6V

(b)    For single phase = 240 x 0.04 = 9.6V

Voltage Drop = (M.D x D x mV/A/m)

                                        1000

Where:    M.D is Maximum Demand (Ampere)

                 D is Distance (meter)

mV/A/m is milivolts / A / meter which is cable impedance value obtain from IEE cable voltage drop Table

 

 Voltage drop from EMSB to ESSB-LP:

               Maximum Demand (MD)      =           600A

               Distance (D)                           =          30m

   mV/A/m                              Z =          0.175 mV/A/m

          (for 4/1C 400mm2 XLPE/PVC cable. Refer to Table4E1B)       

Voltage Drop      = (MD x D x mV/A/m)

                                            1000

                           = 600A x 30m x 0.175

                                             1000

                            = 3.15V

% Voltage Drop  = 3.15V x 100

                                   415V

                            = 0.76%

Voltage drop from ESSB-LP to SUBMAIN 5:

               Maximum Demand (MD)  =           200A

               Distance (D)                       =          75m

mV/A/m                             Z =          0.45 mV/A/m

(for 1 x 4C 95mm2 XLPE/ PVC cable. Refer to Table4E1B)

Voltage Drop      = (MD x D x mV/A/m)

                                            1000

                              = 200A x 75m x 0.45

                                             1000

                              = 6.75V

% Voltage Drop = 6.75V x 100

                                             415V

                              = 1.626%

IEE Wiring Regulations (17th Edition)

Kaedah Merekabentuk Sistem Perlindungan Kilat (IEC 62305 of Lightning Protection Standards)

Sistem Perlindungan Kilat? Macam mana nak rekabentuk sistem perlindungan kilat mengikut standard?

Di sini saya ingin berkongsi berkenaan dengan rekabentuk sistem perlindungan kilat. Seringkali melihat masih terdapat rekabentuk dari sesetengah jurutera yang masih tidak mematuhi rekabentuk berdasarkan IEC 62305. Mari kita lihat dan belajar dari panduan didalam IEC 62305.

1. Kaedah rekabentuk menggunakan kaedah Rolling sphere method (Non Isolated, Air Termination)

2. Memilih kelas Perlindungan Sistem Kilat yang diperlukan. Kebiasaanya, perekabentuk memilih kelas III kerana faktor ianya memadai dari segi perlindungan ke atas bangunan dan mengambikira kekangan kos.

3.  Membuat kiraan jarak antara Rod/Air Terminal yang diperlukan berdasarkan keterangan berikut:-

            Radius, r = 45 meter

            Height of rods, h = 0.5 meter

            So that, the distance between two (2) rods, d = 13.37 meter

4. Jika terdapat peralatan yang ingin dilindungi diatas bumbung contohnya seperti panel Solar, kiraan 'Penetration' perlu dijalankan berdasarkan keterangan berikut:-

Radius, r = 45m

Distance between the two rods, d = 10.37m

So that, the penetration distance = 0.299 m

        

5. Kedudukan Air Terminal adalah seperti berikut:-

6. Jarak antara Down Conductor adalah seperti berikut:-

7. Sistem pembumian. nilai bacaan rintangan adalah perlu kurang dari 10 ohm. Terdapat dua (2) kaedah pembumian yang boleh digunakan iaitu:-

Mudah kan? Kalau ikuti langkah-langkah yang dinyatakan, Insyallah sistem rekabentuk anda adalah mematuhi standard IEC62305 dan anda jangan terkejut jika mendapati ianya amat berbeza dengan apa yang terdapat di dalam lukisan pembinaan ataupun sistem perlindungan kilat yang telah dipasang di tapak ataupun di atas bumbung Apartment rumah anda.

Komponen Elektrik

MCCB – Moulded Case Circuit Breaker

·        Protection against Overload (Thermal Tripping) and Short Circuit (Magnetic Tripping)

-        Thermal tripping (overload) normally can set at 50%, 75%, 100%

-        Magnetic tripping (short circuit) can set for Icu, Ics

·        Standard Rating: 16A, 20A, 25A, 32A, 40A, 50A, 63A, 80A, 100A, 125A, 160A, 200A, 250A, 320A, 400A, 500A, 630A, 800A, 1000A, 1250A, 1600A

·        Pole: 1, 2, SPN, 3, 4, TPN

·        Category: A (no short circuit trip delay), B (in built time delay maybe adjustable): 125A to 1600A

·        Breaking Capacity: 

-        Icu: Ultimate short circuit capacity

-        Ics: Service short circuit breaking capacity

-        Icw: Short time withstand current (0.05 – 0.1 – 0.25 – 0.5 – 1s)

·        Energy liminating class: 1 (no limit), 2 (370 kA²s), 3 (110 kA²s)

·        Example write-up in the drawing:

MCB – Miniature Circuit Breaker
·        MCBs provide overcurrent and short-circuit protection only and are unable to detect residual current (earth leakage current) unless it is large enough to be classed as an overload or short circuit.
·        IEC 60898 (domestic/unsupervised) & IEC 609947-2 (industry/supervised)

·        Standard Rating: 0.5A, 1A, 2A, 3A, 4A, 6A, 10A, 16A, 20A, 25A, 32A, 40A, 50A, 63A, 80A, 90A, 100A, 125A

·        Breaking Capacity: 3 – 25kA

·        Pole: 1, 2, 3, 4

·        Magnetic Trip Type: B (socket), C (lighting, fan), D (Aircond, motor, sodium lighting)
·      Type B MCBs react quickly to overloads, and are built to trip when the current passing through them is between 3 and 4.5 times the normal full load current. They are suitable for protecting incandescent lighting and socket-outlet circuits in domestic and commercial environments, where there is little risk of current surges of a magnitude that could cause the MCB to trip.

·   Type C MCBs react more slowly, and are recommended for applications involving inductive loads with high inrush currents, such as fluorescent lighting installations. Type C MCBs are built to trip at between 5 and 10 times the normal full load current.

·   Type D MCBs are slower still, and are set to trip at between 10 and 20 times normal full load current. They are recommended only for circuits with very high inrush currents, such as those feeding transformers and welding machines.

Type K MCBs are designed to trip at between 8 and 12 times normal full load current, placing them between the traditional

Type C and Type D breakers. In most cases, they allow improved cable protection to be provided in circuits that include motors, capacitors and transformers, where it would previously have been necessary to use Type D devices. This enhanced protection is achieved without increasing the risk of nuisance tripping.

·        Energy liminating class: 1 (no limit), 2 (370 kA²s), 3 (110 kA²s)

·        Example write-up in the drawing:

RCD – Residual Current Device

·       Intended principally to minimise the risk of injury from electric shock, RCCBs provide protection against residual (earth leakage) currents only, and are not sensitive to overloads or short circuits. For this reason, they must never be used as the sole protection device for a circuit.

Circuits with RCCB protection must always include separate protection against overloads and short circuits. This is most often an MCB, but it could, for example, be a fuse.

·       Like MCBs, RCCBs are available in various different types that are designated by letters. This is a potential source of confusion so it’s worth remembering that a Type B MCB, for example, is not related to a Type B RCCB.

·       RCCB (Residual Current Circuit Breaker)

·        RCBO (Residual Current Breaker with Overcurrent)

·        Pole: 2, 4

·        Tripping current: 6mA, 10mA, 100mA, 300mA, 500mA

·        Standard Rating: 10A, 13A, 16A, 20A, 25A, 32A, 40A, 63A, 80A, 100A, 125A

·        Type: G, S (time tripping can be delay)

·        Class: AC, A (recommended), B (3ph inverter), F (1ph inveter)

·        Example Write-up in the drawing:

The earth fault protection system is designed as below:

·   Each incoming power for DB and SSB up to 100A is protected by RCCB (Residual Current Circuit Breaker).

·   Each incoming power for DB and SSB within 125A and 300A is protected by Earth Leakage Relay (ELR),

·  Each incoming power for DB and SSB above 400A and above is protected by Earth Fault (EF) Protection Relay.

·  As additional protection by client, all the outgoing circuit from the MSB and ESSB must be protected by the Earth Fault (EF) Protection Relay.

·   Refer to Energy Commission (ST), the sensitivity for RCD shall be as following:-

-       All installation (1 phase & 3 phase): 100mA (0.1A)

-       Final switch socket: 30mA (0.03A)

-       Wet area, i.e. toilet & wet kitchen: 10mA (0.01A)