Electrical instruments are instruments that use the mechanical movement of electromagnetic meter to measure voltage, power, current, to mention but a few. Electrical technicians require electrical measurement equipment to check the electrical activity and to detect the presence of voltage or current. By using this instrument you can measure electrical parameters such as voltage, frequency, current, power factor, and resistance. Electrical measurements are dependent upon either current or voltage while measuring the frequency you will be measuring the frequency of a current signal or a voltage signal. Browse through this category for various electrical instruments available in Zambian stores.
Electrical and Electronic Instruments
The ammeter, voltmeter, wattmeter are the examples of the electrical measuring instrument. The ammeter measures the current in amps; voltmeter measures voltage and Wattmeter are used for measuring the power.
The oscilloscope is by far the most versatile and frequently used (with the possible exception of the multimeter) of our many electrical instruments.
Multimeter. Multimeter is an electronic instruments used to measure different electrical parameters such as voltage, current, resistance etc. It is the common electronic instruments used to troubleshoot the faults in all electrical and electronic devices.
Voltmeter is an electronic instruments used in an electric circuit to determine the potential difference or voltage between two different points. Digital and analog voltmeters are available in electronics lab. They are usually connected in parallel (shunt) to the circuit. Hence they are designed to have maximum resistance as possible to reduce the loading effect. This device is also common in electronics lab.
Analog voltmeter is a type of voltmeter and electronic instruments with an extra connection of a series resistor (high resistance). It consists of a movable coil placed in a magnetic field. The coil ends are connected to the measuring terminals. As current flows across the coil, it will start turning due to magnetic force excreted on the coil and thus the hair spring will stop the coil by an equal and opposite restoring force. Angular rotation will be proportional to the voltage in this electronic instruments.
Digital voltmeters can measure both AC and DC measurements with high accuracy as an electronics instrument. It can measure a high voltage up to 1 kV. Main component of a digital voltmeter is an Analog to Digital Converter (ADC). Voltage to be measured is amplified or attenuated properly by the circuit and the output is sent to an Analog to Digital Converter (ADC) IC. This IC will convert the analog signal input to digital signal output. A digital display driven by this IC will display the proper voltage value.
Ammeter is an electronic instruments device used to determine the electric current flowing through a circuit. Ammeters measuring current in milli-ampere range is known as milli-ammeters. Common types of ammeters are moving-coil ammeter and moving-iron ammeter. Ammeters are connected in series to the circuit whose current is to be measured. Hence this electronic instruments are designed to have as minimum resistance/ loading as possible. It is used commonly in electronics lab.
Moving Coil Ammeter
Moving coil ammeters are used to measure DC Currents in electronics lab. This electronic instruments consists of a coil suspended by two hair springs. This coil is placed in a magnetic field created by a fixed permanent magnet. A torque is experienced when current passes through this coil which is proportional to the current. When the coil turns, the springs will exert a restoring force proportional to the angle turned. By these two forces, the coil will stop at some point and the angular deflection will be proportional to the current.
Moving Iron Ammeter
Moving iron ammeters as electronic instruments can be used for measuring both direct and alternating currents in electronics lab. In this type of ammeter, a piece of soft iron is used. This iron piece constitutes of a moving vane and a fixed vane. Current to be checked flows through a fixed coil placed around the iron piece. This coil produces a magnetic field proportional to the current. So the iron pieces will get magnetized with the same polarity. The movable vane turns away from the fixed vane due to magnetic repulsion. As the iron turns, the spring of the electronic instruments will exert a restoring force and stop the vane, when both the forces become equal. The pointer of the ammeter is attached to the movable vane, which will point to the proper current reading using a calibrated scale.
Oscilloscope is an electronic instruments used to measure constantly varying signal voltages. This instrument will provide a graphical representation of the input signal on its screen and hence it is used in electronics lab. Cathode Ray oscilloscope is the main type of oscilloscope. It consists of a cathode ray tube and its associated circuits.