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Multimeters are the workhorses of electrical measurement. They combine the capability of measuring voltage (Volts),
resistance (Ohms) and DC current (Amps). In general, the meters have a variety of internal circuits. The circuits are selected using a selector switch. The test leads are
then plugged into the appropriate receptacles on the meter. Then when the test points are applied to the electrical components to be tested, the multimeter display provides the
value. There are many configurations and capabilities. Their costs vary depending on capabilities, accuracy and measurement ranges
 The lower cost analog units, typically in the under $50 range, measure voltage under 600 volts,
resistance up to 20 Megohms with very low resolution (1000 ohms) and current up to 600 milliamps. The accuracies of these units is around +/- 4% of the scale value.
An upscale analog meter runs around $250 which includes higher capacities and overload protection
which is quite handy when you try to measure current higher than the selected scale. Doing this with one of the generic low cost
models, cooks it promptly and you get to go buy another one. Accuracies on these units is in the +/- 2% full scale range.
Digital models are very popular and affordable. The digital display is much
easier to read than the needle scale on the analog units.  Cost ranges for the hand held units are similar to their analog counterparts but accuracies are typically 10 times better.
A high end portable unit costs around $300 with a very broad range of capabilities including True RMS
measurement, AC and DC voltage to 1000 Volts , AC and DC current up to 10 amps, Resistance to 40 Megohms with 0.1 ohm resolution, Capacitance
from 5 nanofarads to 50 microfarads, Frequency from 0.5 Hertz to 200 Kilohertz.
Bench test units cost in the $800 to $1200 range but the accuracies are in the +/- 0.025% range.
Measurement of current over 10 amps requires either a separate meter or an
adaptor for a multimeter. The multimeters typically evaluate current by running the current through a resistor in the meter. While this is a good method, the
size of resistor for high currents is considerable. The typical attachment is a “clamp on” meter. The jaws of this device can be opened, fitted around the
conductor and then allowed to close. The current flowing through the conductor generates a voltage in the wire wraps inside the clamp on meter which can be
converted to a current value by the multimeter. This voltage can then be converted to a current. These clamp on attachments generally run between
$50 and $100 for AC current and from $150 to $300 for AC and DC capability.
The separate clamp on meters for current measurement typically range
between $100 and $500 with the more costly units having digital voltmeters and resistance measuring capabilities.
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