Page 328 - CTS - Mechanic Diesel - TP

MECHANIC DIESEL - CITS

EXERCISE 18.2: Test For Continuity and Insulation

Resistance of Alternator

Objectives

At the end of this exercise you shall be able to
• read and interpret the name-plate details of an alternator
• identify the terminals of a 3-phase alternator
• test the alternator windings for continuity
• test the insulation resistance between the stator and rotor windings
• test the insulation resistance, between the windings and the alternator frame.

Requirements

Tools/Equipments Equipment/Machines
• Cutting pliers 200mm - 1 No. • Alternator, 3-phase, 3 KVA 415V - 1 No.
• Spanner set 5mm to 200mm - 1 Set Materials
• Screwdriver 200mm - 1 No.
• Screwdriver 100mm - 1 No. • P.V.C. insulated copper wire
• Megger 500V - 1 No. 23/0.2 mm size - 5 m
• Insulation tape - 1 m.
• Test lamp 60W / 240V - 1 No.

Procedure

TASK 1: Read and interpret the name plate details of an alternator
1 Read and interpret the name-plate details of the 3-phase alternator and enter in Table 1.
2 Identify the terminals of the alternator as you did in Exercise No.3.5.151. Task : 3.
Table 1
Name Plate Details
Manufacturer, Trade mark : ...........................................
Type, model or list number : ..........................................
Type of current : .......................................... Fabrication or Serial number : ........................
Function: .......................................... Alternator : ........................
Type of connection: .......................................... P.F : ........................
Rated voltage: ..................................Volts Rated current : ............................. amp
Frequency: ......................................Hz Rated speed : ..............................r.p.m.
Rated power: ...................................kVA Rated exc. current: ..............................amps
Rated exc. voltage: ..................................Volts Direction of rotation: ......................................
Rating class: .......................................... Protection class: ......................................
Insulation class: ..........................................

TASK 2: Conduct continuity test by using a lamp
1 Take the test lamp and identify the cable to which the S.P. switch and the fuse are connected in series with the
lamp. Use this as Prod 1.
2 Connect Prod 2 to terminal `N’ and touch the terminals R, Y and B alternatively by Prod 1. (Fig 1) Observe the
lamp condition and enter the same in Table 2.
The phase wire should be identified in the test lamp as Prod 1, and should be connected through
the switch and fuse to the test lamp. Care should be taken to see that the phase wire does not touch
the body or frame of the alternator. Do not touch any terminal while testing with AC supply.

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