1. DISTRIBUTION BOARD :
OVERCURRENT PROTECTION DEVICES

2. -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.

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

4. 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 )

5. Fuse – switch.

6. Fuse – switch.

7. 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.

8. Figure : RCCB use in wiring system

9. Figure : Circuit breaker for final user circuits

10. Figure: RCCB

11. 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 .

14. 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.

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

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

18. Final circuit
Figure : Conection of DB.
E
N L

19. -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. ?

20. Example : Figure of final circuit.

21. Thank you