What Is an AC Millivoltmeter?
An AC millivoltmeter is a device used to measure AC voltage supplied from an AC power source.
In the past, many portable AC millivoltmeters were sold with only the function of an AC millivoltmeter, but in recent years, most AC millivoltmeters have been used as testers with multiple functions. There are two types of multifunctional products: analog testers and digital testers.
Analog testers have relatively low internal resistance, minimizing power loss. They also have the advantage of high accuracy and low measurement error.
Digital testers have high internal resistance and can measure circuits with high impedance.
Uses of AC Millivoltmeters
AC millivoltmeters are widely used in product inspection, maintenance, and preservation where AC current is used.
The following are examples:
- Identifying the cause of audio equipment malfunctions
- Confirmation of receiving and transmitting voltages of cubicles
- Checking the condition of submersible pumps for drainage
- Confirmation of output voltage of emergency generators
- Confirmation of generating voltage at power stations
- Confirmation of transmission and receiving voltage at substations
By using AC millivoltmeter, it is possible to identify the inherent voltages between electronic circuits.
As mentioned above, AC millivoltmeter is also used to monitor equipment voltage conditions.
Principle of AC Milivoltmeters
AC millivoltmeters can be broadly classified into two types: analog and digital.
Analog voltmeters mainly use the moving-piece method.
In the movable iron strip type, an input voltage is applied to a fixed coil, and the magnetic force generated in the coil moves the iron strip to oscillate the pointer. It is characterized by its simple structure and low cost.
The principle of a digital millivoltmeter is it first converts the input AC voltage to DC power via an AC/DC converter. The electrical resistance is then determined by the multiplier, and the amount of current flowing through the AC millivoltmeter is determined by the voltage of the bias current and the voltage of the AC millivoltmeter intrinsic resistance. With the electrical resistance and current determined, Ohm’s law can be used to determine the voltage.
Types of AC Millivoltmeter
As mentioned earlier, there are two types of AC millivoltmeters: analog and digital. Data loggers for logging voltages are also available.
Analog AC Millivoltmeter
Many people think of analog AC millivoltmeters when they hear the words “AC millivoltmeter. The most common type has a voltage plate and needle covered by a transparent acrylic cover on the front. Because of its simple structure, it is less prone to failures and more reliable than a digital AC millivoltmeter.
They are relatively inexpensive, and some are available on mail order sites for less than 10 dollars.
Digital AC Millivoltmeter
This type of voltmeter has a digital display on the front panel to indicate voltage. It has a control board such as FPGA inside and has functions such as an analog-to-digital conversion circuit.
The digital display is easy to read, and some are highly functional because various functions can be realized by the program that controls the board.
The price range varies from those priced in the 1o USD range to high-performance models, costing several thousand dollars.
Compared to analog, the structure is more complex, so the failure rate tends to be higher.
Data Loggers
A data logger is a type of device that has the function of an AC millivoltmeter and can simultaneously log the results of voltage measurements and perform various measurements, such as temperature, by connecting an expansion unit.
It is a type of device that can simultaneously perform various measurements, such as temperature, by connecting an expansion unit.