Electrical Measurements and Instrumentation Full course on slide share

1. AC Bridges
Electrical Measurement and Instrumentation (EE-336)
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2. Contents
• Introduction to AC Bridges
• Impedance Bridge
• Maxwell’s Bridge
• Hay’s Bridge
• Other Bridges
• Frequency Measurement using Wein’s Bridge
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3. AC Bridge
• vibration galvanometers can be designed to work as detectors over the
frequency range of 5 Hz to 1000 Hz, they have highest sensitivity when
operated for frequencies below 200 Hz.
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Head phones or audio amplifiers are popularly used as balance detectors in
ac bridges at frequencies of 250 Hz and above, up to 3 to 4 kHz.
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Transistor amplifier with frequency tuning facilities can be very effectively
used as balance detectors with ac bridges. With proper tuning, these can be
used to operate at a selective band of frequencies with high sensitivity. Such
detectors can be designed to operate over a frequency rang
Selecting the Detector
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4. Equation for Impedance Bridge
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5. Equation for General Impedance Bridge at
Balance Condition
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6. Example
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7. Maxwell’s Inductance Bridge
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8. Maxwell’s Inductance–Capacitance Bridge
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9. Advantages and Limitations of Maxwell’s
Bridge
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10. Hay’s Bridge (Measuring Inductance)
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11. Other Bridges
• Anderson Bridge (Modified Maxwell Bridge for measuring inductance)
• Owen’s Bridge (Measuring Capacitance)
• De Sauty’s Bridge (Measuring Capacitance)
• Schering bridges (Capacitance, dissipation factor, loss angles)
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12. Frequency Measurement by Wein’s Bridge
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13. The End
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