VOM

The three measuring device used in electrical circuits.


You are not connected. Please login or register

Types of Voltmeter

Go to page : 1, 2, 3, 4  Next

Go down  Message [Page 1 of 4]

1 Types of Voltmeter on Wed Aug 15, 2018 3:46 pm

Admin

avatar
Admin
Voltmeter


A voltmeter is an instrument used to measure voltage or electrical potential difference between two points in basic electric circuits. Analog voltmeters move a pointer across a scale in proportional to the voltage of the circuit. Voltmeters may have an accuracy of a few percent of full scale, and are used with voltages from a fraction of a volt to several thousand volts.

Two common voltage measurements are direct current (DC) and alternating current (AC). Although voltage measurements are the simplest of the different types of analog measurements, they present unique challenges due to noise considerations. Analog voltmeters move a pointer across a scale in proportion to the voltage of the circuit; digital voltmeters give a numerical display of voltage by use of a converter.



Types of Voltmeters


1. Analog Voltmeters

Analog voltmeter includes deflecting type of indicating voltmeters. These are of like moving iron, moving coil, electrostatic types of voltmeters. Moving coil instruments are of two types namely permanent magnet and dynamo meter



  • Moving-coil instruments with a permanent-magnet field respond only to direct current. Moving coil instruments consists of permanent magnet to produce magnetic field, and a coil which is wounded on soft iron piece and rotates about its own vertical axis. When the current starts flowing through this coil, deflecting torque is produced according to Lorenz force equation. This torque is directly proportional to the voltage across that particular circuit.

A DC voltmeter is constructed by connecting the resistor in series this instrument and also a very high resistor in parallel with the circuit where we want to measure the voltage. Dynamo meter type Moving coil instrument consists of two coils one is fixed and other is rotating. The interaction of the two fields produced by the pair of fixed coil and moving coil produce a deflecting torque. These are used in DC measurement circuits only this makes this instrument to less usage.


         
Advantages of moving coil instruments

Scale is uniform.
Easily extended for multi range measurements.
Low power consumption.
Stray load currents are very small as compared to moving iron instruments.


  • Moving iron instruments are used in AC circuits. Electromagnetic instruments are divided into simple moving iron, dynamo meter type and induction types of instruments. Again moving iron classified as attraction and repulsion types of instruments. In this also consists of soft iron which is of movable and fixed coils. The interaction of fluxes produced by these two elements produces the deflecting torque. The ranges of these instruments are extended by keeping the resistors in series with the coil. Some of the disadvantages are non uniform scale, stray field current effects on the instrument etc.



Advantages of moving iron instruments

These are used for both AC and DC measurements.
Low cost compared to moving iron instruments.
Torque to weight ratio is high.


  • Electrostatic Voltmeters operating on the electrostatic principle use the mutual repulsion between two charged plates to deflect a pointer attached to a spring. These types of instruments are used for high voltage AC measurements as well as DC. These are of electrostatic disc type capacitor connected across the circuit which is to be measured. The electrostatic voltmeters can be categorized into three types based on the mechanical configuration. Those are repulsion, attraction, and symmetrical. Deflecting system consists of deflector which is suspended from a torsion filament or It can be pivoted by the bearings. Arrangements the elements in this type of instrument mad with some special elements like capacitative elements, including parallel plates, concentric cylinders, hinged plates, etc Motion Damping torque is provided by air or liquid damping vanes or by eddy current damping.


Advantages of electrostatic instruments

These only draw the currents at DC is leakage current and current required to charge the capacitive elements.
High sensitivity.
Capable of measuring smallest charge voltages.
High range of voltage measurement possibility nearly 200KV.


2. VTVMs and FET-VMs

These types of instruments handle DC voltage, AC voltage, and resistance measurements. In this type of voltage measuring device electronic amplifier is used in between the input and the meter. Due to this arrangement the current drawn from the circuit under test is reduced. The range of resistances used at the input side in range of 1-20 mega ohms. By these resistances variation we can select the range to be measured. If this instrument uses the vacuum tube in the amplifier then it is called as vacuum tube voltmeter. These are used in high power AC measurements. As the invention of solid state devices used in the amplifiers, these type of voltmeters are called FET-VM.


Advantages

These have high input impedance hence loading error is less.
Non linearity’s is almost eliminated.
Ability to indicate slowly varying voltages.


3. Digital Voltmeters

Voltmeter accuracy is affected by many factors, including temperature and supply voltage variations. DVMs display the measured voltage using LCDs or LEDs to display the result in a floating point format. Obviously, if voltage measurements are taken and the results are displayed digitally with LED or LCD displays, the instrument has to contain an A/D converter. Using a programmed micro controller, ADC and LCD display, the following circuit is ready to provide accurate digital display of analog values from 0 to 15 volts DC. These are used because of the properties like accuracy, durability and extra features. These are completely eliminates the parallax errors. It will convert the signal under test and then amplifies it.


Advantages

Reduces the parallax errors.
Auto ranging.
Automated Polarity.
High resolution instrument includes high precision.

Digital Electronic Voltmeter Circuit Design

The digital voltmeter design uses a microcontroller which is said to be highly efficient in handling the data carrier operation in terms of being faster, error-free and accurate. Rather than using the absolute analog ways of finding out the voltages, the digital voltmeter provides much more precise and accurate values of voltages in a given circuit in the range of the voltmeter.




I hope this helps!

View user profile http://curteneyarellano.forumotion.asia

2 Re: Types of Voltmeter on Sun Aug 19, 2018 1:17 pm

denden

avatar
guru
guru
what is advisable to use for the students the analog or digatal???

View user profile

3 Re: Types of Voltmeter on Sun Aug 19, 2018 1:32 pm

denden

avatar
guru
guru
The analog voltmeter consists of a sensitive galvanometer (current meter) in series with a high resistance. The internal resistance of a voltmeter must be high. Otherwise it will draw significant current, and thereby disturb the operation of the circuit under test. The sensitivity of the galvanometer and the value of the series resistance determine the range of voltages that the meter can display.



The digital voltmeter shows voltage directly as numerals. Some of these meters can determine voltage values to several significant figures. Practical laboratory voltmeters have maximum ranges of 1000 to 3000 volts (V). Most commercially manufactured voltmeters have several scales, increasing in powers of 10; for example, 0-1 V, 0-10 V, 0-100 V, and 0-1000 V.

View user profile

4 Re: Types of Voltmeter on Sun Aug 19, 2018 1:42 pm

denden

avatar
guru
guru
VOLTMETER is an electronic measuring instrument that combines several measurement function in one unit.
- it can measure voltage,current and resistance

View user profile

5 Re: Types of Voltmeter on Sun Aug 19, 2018 1:45 pm

denden

avatar
guru
guru
The voltmeters were established by a Danish physicist named Hans Christian Oersted (1777-1851) in 1820, when he discovered that an electric current in a wire produced a magnetic field around it.

View user profile

6 Re: Types of Voltmeter on Sun Aug 19, 2018 1:52 pm

denden

avatar
guru
guru
Parts of the VOLTMETER
1.ZERO OHM ADJUSTMENT- use to set pointer exactly on zero position at the right side of meter panel.
2.ZERO ADJUSTMENTS SCREW-use to set the meter pointer to zero position at the left side of the meter panel.
3.RANGE SELECTOR/MULTIPLIER- it is used to adjust the proper function range for specific.
4.OHMMETER SCALE- a non- linear scale where reading is based.
5.TEST PROBES- serves as the input portion.
*RED PROBES - positive
*BLACK PROBES - negative

View user profile

7 Re: Types of Voltmeter on Sun Aug 19, 2018 2:46 pm

denden

avatar
guru
guru
denden wrote:what is advisable to use for the students the analog or digatal???


students need to be familiarized in analog than using digital even the digital can get the exact value its better to use for students to use the analog.

View user profile

8 Re: Types of Voltmeter on Mon Aug 20, 2018 3:26 pm

RT


guru
guru
What is the most efficient type of volt meter?

View user profile

9 Re: Types of Voltmeter on Mon Aug 20, 2018 3:31 pm

RT


guru
guru
denden wrote:what is advisable to use for the students the analog or digatal???
It is more convenient to use digital volt meter but of course you have to start first with the basic which is the analog.

View user profile

10 Re: Types of Voltmeter on Mon Aug 20, 2018 3:35 pm

RT


guru
guru
What is easier to measure the direct or alternating current?

View user profile

11 Re: Types of Voltmeter on Mon Aug 20, 2018 4:06 pm

RT


guru
guru
You mentioned there is two common voltage measurement AC and DC . Can you differentiate the two?

View user profile

12 Re: Types of Voltmeter on Tue Aug 21, 2018 7:10 pm

is there any disadvantage of a digital voltmeter?

View user profile

13 the alternating current on Tue Aug 21, 2018 7:11 pm

RT wrote:What is easier to measure the direct or alternating current?



Last edited by rusellee on Tue Aug 21, 2018 7:18 pm; edited 1 time in total

View user profile
denden wrote:what is advisable to use for the students the analog or digatal???

View user profile
RT wrote:You mentioned there is two common voltage measurement AC and DC . Can you differentiate the two?

View user profile

16 Re: Types of Voltmeter on Tue Aug 21, 2018 7:25 pm

A basic analog voltmeter consists of a sensitive galvanometer (current meter) in series with a high resistance.

View user profile

17 Re: Types of Voltmeter on Tue Aug 21, 2018 7:25 pm

Most commercially manufactured voltmeters have several scales, increasing in powers of 10; for example, 0-1 V, 0-10 V, 0-100 V, and 0-1000 V.

View user profile

18 Re: Types of Voltmeter on Tue Aug 21, 2018 7:26 pm

An oscilloscope can be used to measure low voltages; the vertical displacement corresponds to the instantaneous voltage. Oscilloscopes are also excellent for the measurement of peak and peak-to-peak voltages in AC and RF applications. Voltmeters for measuring high potential differences require heavy-duty probes, wiring, and insulators.

View user profile

19 Re: Types of Voltmeter on Wed Aug 22, 2018 3:15 pm

papanicurt


beginner
beginner
RT wrote:What is the most efficient type of volt meter?

The digital type of voltmeter is more efficient to use.

View user profile

20 Re: Types of Voltmeter on Wed Aug 22, 2018 3:43 pm

additional info.
ANALOG VOLTMETER –

An analog voltmeter is the one which has a scale which moves in proportion to the current’s voltage. Higher the current higher the scale moves. Any measurement that is convertible to voltage can be measured on analog voltmeter that is accurately calibrated. The examples of such measurements are pressure, temperature, liquid flow (viscosity). A basic analog voltmeter consists of a galvanometer in series with a high resistance. The combination of accuracy of galvanometer and the resistance, determine the range of voltages that can be measured by the voltmeter.

View user profile

21 Re: Types of Voltmeter on Wed Aug 22, 2018 3:47 pm

Classification of Voltmeter

1.Parmanent Magnet Moving coil (PMMC) Voltmeter.
2.Moving Iron (MI) Voltmeter.
3.Electro Dynamometer Type Voltmeter.
4.Rectifier Type Voltmeter
skl

View user profile

22 Re: Types of Voltmeter on Wed Aug 22, 2018 4:06 pm

Modern voltage measurement is most often performed using digital voltmeters due to their superior accuracy and precision. Analog meters have several advantages over digital types:

1.Analog needle movement gives a better idea of order of magnitude and trends than a digital readout.
2.Analog meters do not require a power supply beyond the test current source.

View user profile

23 Re: Types of Voltmeter on Thu Aug 23, 2018 12:34 pm

Admin

avatar
Admin
RT wrote:What is easier to measure the direct or alternating current?

Both direct and alternating current are easy to measure.

View user profile http://curteneyarellano.forumotion.asia

24 Re: Types of Voltmeter on Thu Aug 23, 2018 2:46 pm

Is Voltmeter has analog and digital type?

View user profile

25 Re: Types of Voltmeter on Thu Aug 23, 2018 2:47 pm

What is the most efficient type of volt meter?

View user profile

Sponsored content


Back to top  Message [Page 1 of 4]

Go to page : 1, 2, 3, 4  Next

Permissions in this forum:
You cannot reply to topics in this forum