# differential transformer

Also found in: Acronyms.

## differential transformer

[‚dif·ə′ren·chəl tranz′fȯr·mər]
(electricity)
A transformer used to join two or more sources of signals to a common transmission line.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

## Differential transformer

An iron-core transformer with movable core. A differential transformer produces an electrical output voltage proportional to the displacement of the core. It is used to measure motion and to sense displacements. It is also used in measuring devices for force, pressure, and acceleration which are based on the conversion of the measured variable to a displacement.

Various available configurations, some translational and others rotational, all employ the basic circuit shown in the illustration: a primary winding, two secondary windings, and a movable core. The primary winding is energized with alternating voltage. The two secondary windings are connected in series opposition, so that the transformer output is the difference of the two secondary voltages. When the core is centered, the two secondary voltages are equal and the transformer output is zero. This is the balance or null position. When the core is displaced from the null point, the two secondary voltages are no longer alike and the transformer produces an output voltage. With proper design, the output voltage varies linearly with core position over a small range. Motion of the core in the opposite direction produces a similar effect with 180° phase reversal of the alternating output voltage. See Transducer, Transformer

Basic circuit of differential transformer
McGraw-Hill Concise Encyclopedia of Engineering. © 2002 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
The measuring system consists of a linear voltage differential transformer (LVDT) connected to the appropriate probe.
Typically, linear variable differential transformer (LVDT) probes check the dimensions in question--most often after a crimping or staking operation.
Traditionally, these systems use an electric motor, motor encoder, gearbox and a transformer-based servo feedback device such as a linearly variable differential transformer (LVDT).
India, May 18 -- Electro Standards Laboratories has launched model 4215-LVDT Smart Indicator, designed for the measurement and control of dual channel Linear Variable Differential Transformer (LVDT) measurement fixtures.
An LVDT (linear variable differential transformer) device is basically an analog differential position sensor (an electromechanical transducer) that outputs a signal proportional to the displacement of a separate, movable core.
The flow rate was adjusted with the inlet valve until a differential pressure of 8 pounds per square inch was measured across a half-inch fixed orifice using the two pressure transducers, which are of the linear variable differential transformer (LVDT) type.
The TMA is composed of a quartz sample holder (platform), a metal/quartz probe which is movable in the vertical axis and a linear vertical differential transformer. The probe contains an element which forms the core of the transformer.
Diode output controls the displacement--and hence the output-- of a differential transformer.
A new Linear Variable Differential Transformer (LVDT) has been developed to measure mirror position on the James Webb Satellite
CSEM makes the miniature sensor using a differential transformer with a thick copper coil for the generator and aluminum coils for detection.

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