DISTRIBUTION BOARD :OVERCURRENT PROTECTION DEVICES

The distribution board is an assemblage of parts including one or more fuses or circuit breakers, arranged for the distribution of electrical energy to final circuits or to other distribution boards.

Main function of distribution board is to protect the circuit and electrical equipment. Figure: Distribution board.

Figure :below shows a 1 pole and neutral, 4 way.

i. Main Switch ( Suis utama ) Main switch is mecanical control to open and conect the circuit manualy.

Two types of main swithch :

a. Switch fuse . - Domestic use.

b. Fuse switch. - Have switch and fuse. Example : Single Pole and Neutral ( SPN ) Triple Pole and Neutral ( TPN )

Fuse switch.

Fuse switch.

ii . Circuit Breaker .

Earth Leakage Circuit Breaker. ( ELCB ) Pemutus Litar Bocor ke Bumi. ( PLBB )

Residual Current Circuit Breaker ( RCCB)

- Two type of ELCB . a. Earth Leakage Circuit Breaker . Current control.

b. Earth Leakage Circuit Breaker . Voltage control.

Figure : RCCB use in wiring system

Figure : Circuit breaker for final user circuits

Figure: RCCB

iii. Miniature Circuit Breaker ( MCB) Pemutus Litar Miniatur

These are increasingly used for excess-current protection in single phase, 240 V circuits. The circuit breaker is essentially a switch which may be;

(a) Opened and closed by hand.(b) Opened automatically when overloaded.

The tripping action may be either magnetic or thermal. In general both of these actions are used in this type of circuit breaker.

Protection against sustained overcurrent is given by the bending of bi-metal strip with its time-lag effect, while high speed protection against a short circuit have given by magnetic operation .

Jenis magnet terma:

Pelantik akan terkendali dalam jangkamasa lama. Kendalian akan dilakukan oleh alat sesentuh dwilogam (bimetal). Apabila arus lebih melaluinya, bahan logam yang satu akan pelantik dan terlepas daripada sentuhan lalu mengendali pelantik sistem mekanisma suis ke arah OFF.Pelantikan serta merta dikendalikan oleh satu alat elektromagnet bagi beban lebih di sekitar 10 x kadaran arusnya.

Size of MCB :

3 Amp - Bell circuit , circuit outlet in toilet.6 Amp - Lighting circuit.20 Amp - Circuit outlet 2 unit in serial , air cond, 32 Amp - Circuit outlet in ring circuit look at MS IEC 60430. Cooking control unit.40Amp -

100 Amp -

Figure : Graph of time current characteristics ( time vs current )

Final circuitLNEFigure : Conection of DB.

Use the diversity factor ( faktor keperbagaian ) to calculate and MCB ratio size.

Example :

- Use the pandaflour light ( lampu kalimantang ) 40 W. And voltage supply 240 V. Try to calculate ,how many light can use as MCB is 6 Amp. ?

Example : Figure of final circuit.

Thank you

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