Electrical Measurements - Stiga MPV 320W Workshop Manual

WORKSHOP MANUAL Chapter EDITION PAGE
MPV 320W / 520W 7 - ELECTRICAL SYSTEM 2017 51 /
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Meters of this kind are available in many forms and all change functions and ranges with switches,
or by plugging test leads into different jacks. Multimeters are available in two basic types, Analog
and Digital.
• Analog Meters
Analog meters have a needle that provides the reading moving along a scale. The longer the
scale, the easier it is to read and more accurate the reading will be. A jewelled movement is used
in this type of meter which is more likely to be damaged through rough handling (except for over-
loaded Protected Meters) or by measuring high values that exceed the range set on the meter,
than a digital meter.
They provide excellent service for the money as long as they are used with care.
• Digital Meters
Digital Meters have no movement and are therefore more sturdy. The reading shows up directly on
a display window of some type. Since they read directly, no skill in reading the scale is required,
nor is it necessary to set the range. The meter switches the ranges automatically.
The user only has to select the function volts DC, AC amps, ohms, etc.), connect the test leads
and the reading is displayed on the display. Because of the internal circuitry and the lack of a
movement, these meters are not likely to be damaged by overloads.
In the discussions that follow, either type of meter may be used. Test procedures are the same.
It is best to learn proper procedures, even though some meters may be more forgiving of mistakes.
Where differences in use may occur, they will be covered in the explanations.

7.1.5 Electrical measurements

• Voltage Measurement
There are two basic rules to be remembered when using a voltmeter. A voltmeter measures the
voltage difference between the test leads and the voltmeter is always connected across the circuit
under test.
• Current Measurement
The two rules to remember when measuring current with an ammeter are; an ammeter measures
the current that flows through the meter, and to measure current an ammeter must be connected
into the circuit.
The latter rule means that the circuit must be opened, and the ammeter wired into it. Because this
procedure is usually difficult, an ammeter is seldom used for troubleshooting.
• Resistance Measurement
An Ohmmeter is used to make resistance measurements and to check continuity through wires
and electrical components.
There is one rule to keep in mind when using an ohm meter. The ohmmeter has a self contained
battery and requires no electrical power. Using the ohmmeter on a circuit that has voltage applied
may result in damage to the meter.