Page 68 - CITS - Electrician - Trade Practical

ELECTRICIAN - CITS

EXERCISE 27 : Identify various types of capacitors,

charging / discharging and testing

Objectives

At the end of this exercise you shall be able to
• identify the type of capacitor by visual inspection
• identify the capacitor’s value and rating from the marking
• test the capacitor with DC supply for insulation and leakage
• test the capacitor for charge and discharge.

Requirements

Tools/Equipments Materials

• Combination Plier (165 mm, insulated) - 1 No. • Capacitors - paper, mica, electrolytic, Mylar,
• Screw Driver (150mm, insulated stem) - 1 No. tantalum, variable air core and mica (Assorted
• Neon Tester 75mm, 500 V - 1 No. values/voltage ratings) - as reqd.
• Variable Dc power supply 0-30 v DC - 1 No. • Connecting wire 1.0 mm - as reqd.
2
• Digital multi-meter 3 Digit, 750 V AC - 1 No. • One way switch 6 A - 1 No.
1/2
• Ammeter 100mA MC - 1 No. • Two way Switch 6 A - 1 No.
• Volt meter 0-250v, MC - 1 No.

Procedure

TASK1 : Identification of capacitors
1 From the capacitor provided by the instructor identify its type.
2 Read the value of capacitance and working voltage from the markings, if indicated, and record in table 1

TASK 2 : Test the capacitor for charge and discharge

1 Form the 12V circuit for testing the capacitor circuit elements.
2 Keep the switch S1 connected to the battery closed. And put the two way switch in position 1
3 Observe the deflection in the ammeter and voltmeter.
4 Record the deflection in the ammeter

5 Observe the voltmeter reading at equal intervals of time.
6 Open the switch ‘S’ and observe the voltmeter reading for few minutes.
7 Close the switch S to position 2 and observe the Close the switch S to position 2 and observe the voltmeter
and ammeter readings.

TASK 3 : Testing of capacitor with ohmmeter
1 Discharge the given capacitor.

2 Connect the ohmmeter to test the capacitor and observe the deflection in the meter.
Result
Identified various types of capacitors and it’s charging / discharging and testing.
Conclusion
1 Charging: at the time of charging capacitor voltage increases as the current and resistor voltage decrease

2 Fully Charged: capacitor voltage equals source voltage, current zero

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