Workshop Assignment, Assignments of Electrical Circuit Analysis

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ASSIGNMENT 1

Wiring (Single Phase)

Introduction

1. Single phase supply with nominal

voltage of 230V, range +10%, -

2. Three phase supply with nominal

voltage of 400V, range +10%, -

3. Permitted frequency is 50 Hz

4. Earthing system type (TT system)

MCCB RCD^ MCB

kW Hour Meter

◦ (^) Distribution Board Set

3 Pin Socket

SSO

3 Pin Plug

Installation and wiring test

1. Supply system Electricity supply for domestic consumers, according to MS IEC 60038 standards, meets the following specifications: -

1. Single phase supply with nominal voltage of 230V, range +10%, -6%;
2. Permitted frequency is 50Hz + 1%;

5. Conduit wiring ◦ (^) Conduit wiring uses PVC cables that are threaded through PVC or steel conduit pipes. ◦ (^) If the pipes run on the surface of the walls and ceilings, it’s called surface conduit wiring. If it runs inside the surface of the walls and covered with plastering, it’s called concealed conduit wiring.

◦ (^) What is wiring testing?

• (^) When there is some progress in electrical wiring, electrical continuity among different lengths of wires and cables is tested; otherwise lamps connected in the circuit afterwards may not burn. This test is specially important where many wires or cables are drawn through the same conduit or casing. i. Continuity Test; ii. Insulation Resistance Test; iii. Polarity Test; iv. Earth Electrode Resistance test; and v. Residual Current Device Test.

Insulation Resistance Test i. Ensure that there is no leakage current between phase conductors, phase and neutral conductors and phase conductor and earth. ii. Test the strength of the cable insulation. iii. Test Equipment – Insulation Resistance Tester.operating voltage is 250VDC or 500VDC. iv. Test Method:

1. Switch off main switch;
2. Disconnect all loads;
3. Switch on all circuit control switches;
4. Carry out test as in the Table below;
5. Meter reading value shall be less than 1 Megaohm.

Polarity test i. Ensure that each fuse or single pole control and protection device is connected only in the phase conductor. ii. Intermediate contact of Edison screw lamp holder is connected to the phase conductor. iii. Ensure that phase, neutral and earth conductors at socket outlets are connected at the correct terminals. iv. Test Equipment – Multimeter (Ohm range) or Ohm meter. v. Test Method:

1. Switch off Main switch;
2. Disconnect all loads
3. Switch on all circuit control switches;
4. Carry out test as in Figure 8.5;
5. Test switches and single phase control devices at the phase conductors.
6. Test socket outlet connection sources.
7. Test Edison screw lamp holder connections.
8. Meter reading value shall be less than 1 ohm.

Residual Current Device Test i. Ensure that the residual current device (RCD) trips within the set time on the occurrence of current leakage to earth. ii. Test Equipment – RCD Tester/ RCCB Tester iii. Test Method :

1. Use the Trip Test Button
2. Press the trip button found on the RCD to determine ifIt trips or otherwise. This test would not be able to determine the sensitivity of the RCD nor the time taken for it to trip.