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Basic Instruments and Measurements. Chapter 2. Basic Analog Meter. D’Arsonval movement – stationary magnet, moving coil galvanometer. Iron Vane Meter – two pieces of iron are placed inside a hollow core solenoid. Current causes magnetic field to move a needle.
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Basic Instruments and Measurements Chapter 2
Basic Analog Meter • D’Arsonval movement – stationary magnet, moving coil galvanometer. • Iron Vane Meter – two pieces of iron are placed inside a hollow core solenoid. • Current causes magnetic field to move a needle. • Extreme caution and care when handling an analog meter. • Proper polarity must be maintained
Meter Scales • Linear meter scale – marks are evenly spaced. • Note what range the dial of meter is set to when reading the value of the scale.
Ammeter • Measures electrical current in a circuit. • Amperes • Milliamperes • Microamperes • Shunt is used to direct excess current away from meter. • Always connected in Series with the circuit.
Voltmeter • Measures electrical voltage present in a circuit: • Volts • Millivolts • Connected in Parallel with the circuit
Ohmmeters • Measures the resistance of a device or part of a circuit: • Megaohms • Ohms • Milliohms • Microhms • Zero the meter • Battery inside the case used to measure resistance.
Other Meters • Volt – Ohm – Milliammeter (VOM) • Digital Multimeter (DMM) • Computer Display meters
Electrical Diagrams • Schematics • Wiring Diagrams • Symbols (see page 453 – 454)