Page 232 - CITS - Electrician - Trade Practical

ELECTRICIAN - CITS

EXERCISE 91 : Check single - & double-layer winding

Objectives

At the end of this exercise you shall be able to
• demonstrate rewinding of three phase single layer winding
• demonstrate rewinding of three phase double layer winding.
Requirements

Tools/Instrument Tools/Instrument
• SEC cu wire - 400g. • Winding former
• Electric soldering iron 25W/240V - 1 No. Materials
• Hack saw blade - 1 No. • Soldering paste - 10g.
• Standard wire gauge
• Resin core solder 60:40 - 50g.

Procedure

Task 1:

1 Demonstrate to calculate no of poles of motor from recorded name plate details
2 Dismantle motor
3 Identify motor winding as single layer or double layer, whole coil or half coil.
(Single layer,no coils=half no of slots, double layer, no coils=no of slot)
(whole coil, no polesxno of phases=no of groups and half coil, no of ploes x no of pair poles = no of groups)
4 Record no of slot, no of coils and pitch

5 Demonstrate the group and lead connection
6 Measure overhang projection at both side
7 Record size of wire, whether single strand or multi wires, wire insulation
8 Remove wedges from slot.

9 Use thinner in winding and remove carefully it to measure coil length, coil width and coil thickness
10 Remove all the coils and measure the weight.
11 Clean the stator slot by brush or compressed air
12 Record the coil length, coil width and coil thickness
13 Prepare stepped winding former to suit recorded dimensions

14 Wind the recorded number of turns, with wire of measure size and insulation
15 Tie the coils with binding thread on overhead sides
16 Keep a connection length at both ends of around 150mm
17 Remove wound coil from stepped former

18 Verify the dimension correctness by placing in the motor slot
19 Make corrections if necessary for dimensions and make required no of coils
20 Shape the coils for inserting into slots with overhang
21 Prepare slot insulation to project above the slot by 10mm both sides
22 Insert left coil side of coils, as per developed diagram for slot upto right side of first coil.

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