MAC TOOLS EM721 Manual Del Usuario página 17

5. BASIC ELECTRICAL TESTS AND MEASUREMENTS
One of the most common electrical diagnostic tools is a digital multimeter (DMM). A DMM is simply an
electronic yardstick for making electrical measurements.
DMMs have many special functions and features, but the most common use is to measure voltage, current, and
resistance. An automotive multimeter such as this automotive multimeter can also measure frequency, RPM,
duty cycle, dwell, pulse width, temperature, capacitance, and even the condition of diodes.
General Considerations for Making Measurements
•
Accuracy
A measurement range determines the highest value the meter can measure. Most Meter functions
have more than one range. When making a measurement, it is very important that you are in the right
measurement range. Selection of a lower range moves the decimal point one place to the left and increases
the accuracy of the readings. When the LCD shows OFL (overload), the range is too low; select the next
higher range.
•
Analog Bargraph
The bargraph is useful for trend setting or directional data. It is easiest to read when the data causes the
digital display to change rapidly.
•
Safety Shutter
When measuring voltage, be sure that the red test lead is connected to the
" " input jack; if the red test lead is connected to the "A" or "mA μA" jack, you may be injured or the
meter may be damaged. When measuring current, do not connect the red test lead to the "
jack. The safety shutters of the meter are used to prevent inadvertent connection to wrong input terminal.
Voltage Measurements
Voltage measurements are dynamic tests that measure the voltage across a circuit or component with the power
on. Voltage measurements are made with the test leads connected across the circuit element under test.
TO AVOID ELECTRICAL SHOCK AND INSTRUMENT DAMAGE, INPUT VOLTAGE MUST NOT EXCEED
1000V DC OR 750V AC RMS. DO NOT ATTEMPT TO MEASURE ANY UNKNOWN VOLTAGE THAT
NOTE: When making voltage measurement, this meter must be connected in parallel with the circuit or circuit
element under test.
800.MACTOOLS
All manuals and user guides at all-guides.com
WARNING
MAY EXCEED 1000V DC OR 750V AC RMS.
" input
17