24-01-2013, 03:05 PM
Digital Instrumentation
Digital Instrumentation.pptx (Size: 2.38 MB / Downloads: 39)
Moving-Coil Meter
Types of Meters
Analog meter:
Uses a moving pointer and a printed scale to indicate values of voltage, current, or resistance.
Volt-Ohm-Milliammeter (VOM):
Allows all three kinds of measurements on a single scale or readout.
Digital multimeter:
Uses a numerical readout to indicate the measured value of voltage, current or resistance.
Direct Current Meters
Direct current in a moving-coil meter deflects the pointer in proportion to the amount of current.
A current meter must be connected in series with the part of the circuit where the current is to be measured.
A dc current meter must be connected with the correct polarity.
Digital Multimeters (DMMs)
The digital multimeter has become a very popular test instrument.
The digital value of the measurement is displayed automatically with decimal point, polarity, and the unit for V, A, or Ω.
Meter Applications
Table 8-4 (next slide) summarizes the main points to remember when using a voltmeter, ohmmeter, or milliammeter.