Fig. Strain Gauges (source: omega.com) Strain gauge A strain gauge is an electrical transducer which is used for measuring mechanical surface strain. Basic Principle of Strain Gauge When stress is applied to the metal conductor, its resistance changes owing to change in length and cross-sectional area of the conductor. The resistance of the conductor under … Read more
Fig. Thermocouple (source: sterlingsensors.co.uk) What is a Thermocouple? A thermocouple consists of a pair of dissimilar wires joined at one end. It is an active transducer. On the other hand, RTD and thermistors are passive transducers. Thermocouple work on the principle of Seebeck effect. According to Seebeck effect, if two dissimilar metals are joined together … Read more
Piezoelectric Transducer A piezoelectric transducer is one that can generate a voltage proportional to the stress applied to it. These transducers work according to the piezoelectric effect. When a mechanical force or pressure is applied across the piezoelectric crystal, an electric potential appears across the surfaces of crystal. This generation of electric potential is due … Read more
Hall Effect Transducers Hall Effect Transducers are the transducers which work on the principle of hall effect. According to hall effect, if a conducting material strip carries current in the presence of a transverse magnetic field; an EMF is produced between two edges of the conductor in a direction perpendicular to both the magnetic field … Read more
In the previous article, we have learned about Maxwell bridge. It is a modification of Maxwell’s bridge. The circuit diagram for Hay’s Bridge is shown below. It uses a resistance in series with a standard capacitor. L1=unknown resistance having a resistance R1 R2, R3, R4=known non-inductive resistance C4=standard capacitor At balance, e1e4 = e2e3 Separating real … Read more
Ammeter Shunt is used for the measurement of heavy current using an Ammeter. Ammeter Shunt is basically a low resistance connected in parallel with the moving coil so that most of the current is bypassed by the Shunt and hence only a small current flows through the moving coil. Why do we need Ammeter Shunt … Read more
In modern measurement systems, the various components comprising the system are usually located at the distance from each other. It is, therefore, becomes necessary to transmit the data and information between them through some form of communication channel. Telemetry may be defined as measurement at a distance. Telemetry is indicating, recording, integrating a quantity at … Read more
Voltmeters and Ammeters are used to measure the voltage and current in the circuits. Using instrument transformers, ranges of these devices to measure can be increased. A current transformer is basically a step-down transformer; hence it steps down the current. When used in conjunction with the low range ammeter, a current transformer (CT) increases the range … Read more
The operation of moving coil meters depends on the electromagnetic effect of the current (a force is exerted on the current carrying conductor when placed in a magnetic field). Moving coil instruments are of two types Permanent magnet type Dynamometer type Permanent magnet type moving coil instruments can be used only in dc circuits whereas … Read more
A transducer is a device which, when actuated transforms energy from one form to another. Here input quantity is non-electrical quantity. The output quantity may or may not be electrical quantity. When the output quantity is electrical, then transducer is called as Electrical Transducer. An electrical transducer is a device which converts any physical quantity … Read more