Displacement Transducer


Product Description

Magtrol’s line of Displacement Transducers provide contactless measurement of absolute piston position in hydraulic and pneumatic cylinders and other applications. Their robust construction, large insensitivity to shocks and very long life (due to no moving parts and therefore no wear of components) make them both cost effective and very reliable. Magtrol transducers offer a wide range of operational temperatures and admissible pressure resistance for even the most demanding applications.

The transducer provides a direct 4-20 mA output signal corresponding to the measuring range, as well as VDC temperature output. As an option Magtrol offers the CST 113 Signal Converter, which allows the complete chain to be calibrated according to the specific needs, either in current or voltage output.


  • Large measuring range: Piston displacements from 50 to 1000 mm; 80 to 250 mm for DI 63X models
  • Current-based output signal (4 to 20 mA) for displacement
  • Built-in temperature measurement
  • Very long life: No moving parts and therefore no wear of components (Eddy-current principle)
  • Slim measuring system allowing large measuring range
  • Insensitive to metallic impurities in the working fluid
  • High shock and vibration resistance
  • Capable of withstanding pressures up to 450 bar
  • Robust construction, designed for permanent operation in hydraulic systems
  • EMC susceptibility conforms to European standards

Model Comparison and Drawings

Version: Standard Temperature HIGH TEMPERATURE
Models: DI 5XX DI 605 / DI 610 / DI 611 DI 63X
Measuring Range 50 mm to 1000 mm 50 mm to 160 mm 80 mm to 250 mm
Operating Temperature -40 °C to +80 °C -40 °C to +125 °C -40 °C to +200 °C
Displacement Output 4 to 20 mA 4 to 20 mA 20 to 4 mA
Temperature Output 7.5 VDC ±80 mV at 20°C 7.5 VDC ±60 mV at 20°C 7.5 VDC ±60 mV at 20°C
Drawing pdf pdf pdf

Operating Principles

Eddy-Current Principle

Magtrol Displacement Transducers use the principle of Eddy-current measurement. An aluminum tube moves along the transducer’s coil changing the induced Eddy-current losses, thus changing the coil impedance. An electronic circuitry housed in the transducer head, transforms the information of the measuring tube position into a linear signal. This circuitry uses modern SMD (surface-mounted device) technology, giving it robustness and reliability. The sensor is actively compensated for temperature changes.

Characteristics of the Output Signa

DI Series Displacement Transducers have a basic 3-wire configuration, providing a 4–20 mA current (20–4 mA for DI 63X models) proportional to the position of the aluminum tube. An indication of the temperature within the probe is also provided as a voltage output. In closed-loop systems, a specific piston position can be repeatedly achieved with a precision better than 0.05‰ full scale (i.e. better than 50 µm for a measuring range of 1 m).

EXAMPLE: DI 505–516/011 and DI 605–611/011 Transducers

  • Oscillating magnetic field created in the coil (4 kHz, up to 10 kHz depending on the measuring element and/or range)
  • Eddy current generated in the aluminum tube
  • Coil impedance increases when tube moves
  • Measure of inductance variation
  • Current remains constant
  • Demodulated signal transformed into 4–20 mA


The DI series of displacement transducers were developed principally for OEM applications in the hydraulic industry. They enable the direct and reliable measurement of the position of:

  • Hydraulic Cylinder
  • Steam Inlet Valves
  • Propellers
  • Stone Crusher
  • Servo Controls
  • Control Valves

Their design is such that the installation cost is kept to a minimum. This cost-effectiveness results from the limitation to one fixed standard signal of 4 to 20 mA with very precise determination of the measurement interval (from 0 to full scale) on the sensing element.

Hydraulic Cylinder

Displacement sensors are mounted inside hydraulic cylinders. The sensors are highly resistant to vibration, pressure (up to 450 bars) and have an excellent behavior on thermal compensation.


Boat Propeller with Variable Pitch


Steam Turbine – Power Regulation

Displacement Transducers are used in hydraulic servo motors to regulate the position control of steam inlet valves.


Stone Crusher