شهروالنيظام™

6.1 Single Phase System

Description of 1 phase system

Distribution Box

Wiring Specification

Exercise Assignment

شهروالنيظام™

شهروالنيظام™

Pengenalan

Pembahagian merupakan pembekal tenaga daripada sistem penghantaran kepada pencawang - utama dan pencawang kecil kepada pelbagai pengguna.

شهروالنيظام™

SISTEM KUASA PEMBAHAGIAN

12 kV 132kV

132kV

33kV

33kV11kV

11kV

415V/240V415V/240V

POWERSTATION

PE

TRANSMISSION LINE

PEU/G & O/H

U/G & O/H

DISTRIBUTION

شهروالنيظام™

Stesan Kuasa

Penghantaran

Pengagihan

Pengguna

شهروالنيظام™

Single-phase electric power refers to the distribution of electric power using a system in which all the voltages of the supply vary in unison.

Single-phase distribution is used when loads are mostly lighting and heating, with few large electric motors.

شهروالنيظام™

The generation of AC electric power is commonly three phase, in which the waveforms of three supply conductors are offset from one another by 120°.

Standard frequencies of single-phase power systems are either 50 or 60 Hz.

شهروالنيظام™

A single-phase load may be powered from a three-phase distribution system either by connection between a phase and neutral.

In places using a 415 volt 3 phase system, the phase-to-neutral voltage is 240 volts, allowing single-phase lighting to be connected phase-to ground and three-phase motors to be connected to all three phases.

شهروالنيظام™

Single-phase power distribution is widely used especially in rural areas, where the cost of a three-phase distribution network is high and motor loads are small and uncommon.

Picture

شهروالنيظام™

شهروالنيظام™

Standard voltage for :-a. Low Voltage – Exceed low overvoltage but

not exceeding i. 1000Vac @ 1500Vdc between

conductor.ii. 600Vac @ 900Vdc @ between

conductor & ground.b. Low voltage agreed at the national level -

i. 240V – Single phase ii. 415V – 3 phase 4 wire.

HOME

شهروالنيظام™

Distribution Board• An assembly containing switching or protective devices such as fuses, residual current operated devices associated with one or more incoming circuit, together with terminals for the neutral and protective circuit conductors.

• Functions :

1. Low voltage electric power distribution point.

2. Protection for output circuit.3. To cut supply efficiently if any

corruption occurred at the final circuit.

شهروالنيظام™

Miniature distribution box assembly

DISTRIBUTION BOARDMAIN SUPPLIER

UNIT MAIN CONSUMER UNIT

SERVICE FUSE

UNIT PEMOTONG

kWh METER

NEUTRAL CONNECTOR MINIATURE CIRCUIT

BREAKER

EARTH LEAKAGE CURRENT BREAKER

MAIN SWITCH

شهروالنيظام™

SUPPLIER MAIN UNIT

Install outside the building at the wall surface / premise entrance wall.

Easy to be check by the TNB - purposes of the bill @ supply cutting .

Contain of :

Cutting Unit Meter kWj

Service Fuse

(Fius Perkhidmatan)

Neutral connector

(Penyambung Neutral)HOME

شهروالنيظام™

Connected to the main supply inlet

To the phase conductor. To protect user main circuit. To makesure the current across

not exceed the max. limit. Fuse will blow / open cct if

overcurrent occurred. Using catridge type of fuse.

SERVICE FUSE AND NEUTRAL CONNECTOR

Picture

HOME

شهروالنيظام™

شهروالنيظام™

Meter kWj

To measure amount of energy/ power that have been used by the consumer in a certain time of period.

Fixed with cutter unit at the installation main board.

HOME

شهروالنيظام™

Distribution Box

Use to distribute main power supply to final cct @ to sub distribution fuse box.

Contain of life, neutral & earth supply.

Each connection have separate fuse or cct breaker.

The box structure is made of pvk/ plastic

& metal.

شهروالنيظام™

The present fuse box – distribution fuse box miniature type that made with plastic material @ long lasting pvk material. It is also attach with transparent cover that allowed the user to observe the fuse arrangement / cct breaker.

The main fuse , earth leakage cct breaker & fuse / cct breaker (CB) is assemble in miniature form.

Every parts is assemble / arrange in one line form. HOME

Main Component 1. Miniature main Switch (Onload switch

fuse)

Power inlet source is from down side of the main switch.

Power outlet source is from up side of the main switch.

It is in cartridge type. Rate should same with the external fuse

Able to be disassemble via the transparent cover.

Assembly method - by clipping the main switch to the bar

area.

HOME

2. Earth Leakage Cct Breaker (ELCB)

ELCB is a device that protect consumer from electric shock. This gadget must be fitted in every alectric assembly.

If the leakage current is higher than the max spec limit, the switch will be automatically OFF for protection.

Push the ‘T’ small switch to check the RCCB reliability.

For maintenance, this switch need to be check every month to make sure it is in good condition.

• ELCB is a device with two earth terminals used to directly detect currents leaking to earth from an installation and cut the power.

• They were mainly used on TT earthing systems.

• By having the assumption of the presence of current in the earth line, it means there is any leaking current from the main incoming live cable, thus the power has to be cut off to ensure the safety.

• State of ELCB when it cuts the power is

called tripped. Every time the ELCB tripped, we can reset it back (connect back the power line) by resetting the trip button.

• Nowadays, they have been almost totally replaced by Residual-current device (RCD) due to a number of problems:

a. They cannot detect earth faults that do not go through the earthing system.

b. They do not allow a system to be easily split into multiple sections with independent fault protection, due to the fact that earthing systems are usually bonded to things like pipework.

c. They may be tripped by external voltages on something connected to the earthing system such as metal pipes, a TN-S earth or a TN-C-S combined neutral and earth.

HOME

3. Miniature Cct Breaker (MCB) Overcurrent The value should be

higher than the current capacity in the cct.

Overcurrent effect the insulator/ conductor will be damage & can cause fire.

Rated current not more than 100A. Thermal @ thermal magnetic

operation

Picture

1. Actuator lever - used to manually trip & reset the cctt breaker. Also indicates the status (On @ Off/tripped). 2. Actuator mechanism - forces the contacts together @ apart.3. Contacts - Allow current to flow when touching and break the flow of current when moved apart.4. Terminals5. Bimetallic strip6. Calibration screw - allows the manufacturer to precisely adjust the trip current of the device after assembly.7. Solenoid8. Arc divider / extinguisher

شهروالنيظام™

Use as a protector that is in 2 mode :- a. Over current protector – Bi-metal

method b. Failure/ Damage protector – Solenoid

method If the S/C or O/C occur, MCB will

automatically OFF. MCB can be set to ON by push the ON

button. Several type of current for MCB can be

use at the final wiring cct depand to the appropriate condition such as : - Lighting cct 6A

- Power cct 16A - Power cct 20A

1 MCB only can be connected to one small cct.

Picture

HOME

شهروالنيظام™

Normal position breaker ONBi Metal strip bending, about to tripContacts opening, arc formingArc is extinguished, hot gas existContacts fully open

Miniature distribution box assembly

شهروالنيظام™

The picture shows how the main fuse, RCCB and MCB assemble together in the miniature distribution box.

The box size is categorized by the ‘WAY’ term. i.e. 10 way, 12 way, 15 way, & etc.

The higher the no, the bigger the size will be.

This means the quantity of MCB can be add depend to the box size.

Size available in market :

- 2, 4, 6, 8, 10, 12, 15, 18, 21 & 24.

Picture

Picture shown the cct diagram of ‘unit pepotong’

( service fuse, neutral connector & power meter ) with the user

distribution box ( main switch, ELCB & MCB )

شهروالنيظام™

How to check the fuse box?1. Fuse give protection by cutting the flow

of current in the cct if O/C or fault occur.2. When the S/C @ O/L occur, fuse in the

cct will open the cct.3. To get the supply back, we need to

change the fuse.4. Turn off @ dissamble all the equipment

that connected to the cct.5. Change to the new fuse that is same

spec with the broken fuse. i.e. 15 A change with 15 A.

6. Don’t touch the fuse metal area when take off @ install the fuse.

شهروالنيظام™

7. Switch OFF the main swith if the fuse box attached to the main switch.

8. ON the main switch.9. If the fuse broken even no

equipment connected yet to the cct, maybe there is serious fault happened the wiring cct. Call the authorized @ accredited person.

10. If the fuse broken after the equipment connected to the cct, maybe there is S/C occur in the equipment cct.

شهروالنيظام™

Information label at the switch gear switching devices.

Kadaran Vdc dan VacKadaran arusKadaran arus litar pintasNo siriData breaking capacityNo Model

شهروالنيظام™

State type of testing that need to implement for below test :-

Test for conductor protector ( Continuity test)

Test for leakage current at metal box (Insulation resistance test)

Test for circuit breaker operation. ( Ujian kepekaan pemutus litar )

Test to determine the efficiency of earth electrode. ( Ujian Elektrode bumi) HOME