A device that measures the voltage or potential difference between various points across an electrical circuit, is known as a voltmeter.
It has high internal resistance. This is done primarily for the purpose of measuring the potential difference across the two points of the circuit.
Types of the voltmeter
There are seven types of voltmeters based on construction principles given as follows:
Permanent magnet moving coil voltmeter (PMMC): A voltmeter that measures the current in a coil by measuring the coil's angular deflection in a uniform magnetic field is known as a Permanent Magnet Moving Coil (PMMC) voltmeter, also known as a D'Arsonval meter or simply galvanometer. The measured voltage induces a current in the PMMC instrument, which causes the pointer to deflect. For DC measurements, the PMMC voltmeter is used.
Moving iron voltmeter: The moving iron voltmeter (MI) is a device that can measure both AC and DC voltages. The deflection of this device is exactly proportional to the coil voltage. It can be further bifurcated into two types; Attraction moving iron voltmeter and repulsion moving iron voltmeter.
Electro dynamometer type voltmeter: The voltage of both AC and DC circuits is measured using this voltmeter and both the AC and DC measurements are normally calibrated the same way.
Rectifier type voltmeter: These are commonly used to measure voltage in AC circuits. With the help of a rectifier, this voltmeter converts AC to DC.
Electrostatic type voltmeter: The deflection torque is generated by a static electrical field. Several voltmeters are utilized just to evaluate high voltage.
Digital voltmeter: A digital voltmeter (DVM) measures an unknown input voltage by converting it to a digital value, which it then displays in numeric form.
There are two types of voltmeters based on the type of measurement given as follows:
DC voltmeter: The DC voltmeter is a device that measures the peak value of the DC voltage and does not use a rectifier.
AC voltmeter: Before amplifying the signal, an AC voltmeter employs a rectifier to convert the AC signal to a DC signal, which is then transferred to a moving coil magnet meter, which changes the indication of the pointer and therefore measures the RMS (root mean square) value of AC voltage.
