Category: Indicators and Display Devices

Digital Display System

Digital Display System: Digital Display System – The rapid growth of electronic handling of numerical data has bought with it a great demand for simple systems to display the data in a readily understandable form. Display devices provide a visual display of numbers, letters, and symbols in response to electrical input, and serve as constituents […]

Repulsion Type Moving Iron Instrument

Repulsion Type Moving Iron Instrument: A variation of the radial vane instrument is the concentric vane Repulsion Type Moving Iron Instrument. The instrument has two concentric vanes. One vane is rigidly attached to the coil frame while the other can rotate coaxially inside the stationary vane, as shown in Fig. 2.9. Both vanes are magnetized […]

Moving Iron Types Instrument

Moving Iron Types Instrument: Moving Iron Types Instrument can be classified into attraction and repulsion types. Repulsion type instruments are the most commonly used. Iron vane ammeters and voltmeters depend for their operations on the repul­sion that exists between two like magnetic poles. The movement consists of a stationary coil of many turns which carries […]


Electrodynamometer: Electrodynamometer – The D’Arsonval movement responds to the average or dc value of the current flowing through the coil. If ac current is sought to be measured, the current would flow through the coil with positive and negative half cycles, and hence the driving torque would be positive in one direction and negative in […]

Taut Band Instrument

Taut Band Instrument: The Taut Band Instrument utilizes the same principle as the D’Arsonval movable coil and fixed magnet. The primary difference between the two is the method of mounting the movable coil. The taut band movement has the advantage of eliminating the friction caused by a jewel-pivot suspension. The meter has a coil mounted […]

Practical PMMC Movement

Practical PMMC Movement: The basic Practical PMMC Movement (also called a D’Arsonval movement) offers the largest magnet in a given space, in the form of a horse-shoe, and is used when a large flux is required in the air gap. The D’Arsonval movement is based on the principle of a moving electromagnetic coil pivoted in […]

Permanent Magnetic Moving Coil Movement

Permanent Magnetic Moving Coil Movement(PMMC): Permanent Magnetic Moving Coil Movement – In this instrument, we have a coil suspended in the magnetic field of a permanent magnet in the shape of a horse-shoe. The coil is suspended so that it can rotate freely in the magnetic field. When current flows in the coil, the de­veloped […]

Basic Meter Movement

Basic Meter Movement: Basic Meter Movement – The action of the most commonly dc meter is based on the fundamental princi­ple of the motor. The motor action is produced by the flow of a small current through a moving coil, which is positioned in the field of a permanent magnet. This basic moving coil system […]

Types of Instrument

Types of Instrument: Types of Instrument – Analogue ammeters and voltmeters are classified together, since there is no basic difference in their operating principles. The action of all ammeters and voltmeters, except those of the electrostatic variety, depends upon a deflecting torque produced by an electric current. In an ammeter this torque is produced by […]