Piyadanai%20Pachanapan,%20303251%20Electrical%20Instruments%20 - PowerPoint PPT Presentation

Title: Piyadanai%20Pachanapan,%20303251%20Electrical%20Instruments%20


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???????????????????????????? AC Indicating
Instruments
Piyadanai Pachanapan, 303251 Electrical
Instruments Measurement, NU
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????????????????????????????

• ????????????????????????

• ?????????????????????????????

- ???????????????? (AC Voltmeter) ????
???????????????????????????? (Rectifier
Instrument)
- ???????????????????????????????????
(Electrodynamometer)
- ????????????????????????????????? (Iron-Vane
Moving Coil Meter)
- ??????????????????????????? (Thermocouple Meter)
- ?????????????????????? (Electrostatic Meter)
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???????????????????????? DC ??? AC
DC Signal
AC Signal
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????????????????????

• ?????????????????????????????????? (Amplitude)
  ?????? (Direction) ?????????? (Frequency)
  ?????????? (Time Period)

• ???????????????????????? ???? Sine Wave,
  Triangle Wave, Square Wave, Pulse ??? Spike

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???????????????????????????
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????????????????????
Vm
Im
i ??????? v ???????
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???????????????????????? (Induce Voltage (EMF))
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Right Hand Rules Fleming
Induce EMF
Volt
?????
B magnetic flux density, tesla
l conductor length in the field, meters
v relative velocity between field and
conductor, m/s
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????????????????????????? 1 ??? (Instantaneous 1
phase Voltage Generation)
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??? ??? v ??? ??? v
0 0o 0 V 7 210o -0.5 V
1 30o 0.5 V 8 240o -0.866 V
2 60o 0.866 V 9 270o - 1.0 V
3 90o 1.0 V 10 300o -0.866 V
4 120o 0.866 V 11 330o -0.5 V
5 150o 0.5 V 12 360o 0 V
6 180o 0
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????????????????????????? 3 ??? (Instantaneous 3
phase Voltage Generation)
????? 3 ??? ???????????????????? 120 o
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????????????????????????

• ????????????????????????? ?????????????????

• ??????????????????????????????????????
  ????????????? 3 ????

1. ???????????? (Peak to Peak)
2. ????????? (Average Value)
3. ????????????? (Root Mean Square, RMS)
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???????????? (Peak to Peak, Ep-p)

• ????????????????????????????????????????
  ?????????????????????? (Maximum Value)

Ep-p ?????? Peak 2 Peak
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????????? (Average Value, Eav)

• ???????????????????????????????????????????

??????????????????
??????????????????
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???????????????????????????

• ???????????????????????? 1 ??? (T) ????????? AC
  ? 0

• ??? Eav ?? 1 ???????????? AC ???????????? 0

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????????????? (Root Mean Square, Erms)

• ?????????????????????????????????????????????????
  ??????????????????? ???????????? rms
  ????????????????????????????

• ??? rms ??? f (t) ??????? t2 t1 ???

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??????????????????????????????? sine wave ?????
rms ???????
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????????????? (Form Factor)

• ???????????? ??? rms ??? ????????? ??????????????

??????????????????????
?????????????????????