non-contact displacement sensor - MicroStrain - (Version JPG) - Page n° 2 - PDF Catalogue | Technical Documentation

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Displacement sensor, MEMS, LVDT, Signal conditioner, Wireless network

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Differential Variable Reluctance Transducer

Electrical Specifications

(with MicroStrain's DEMOD-DVRT)

How it works

Two coils within the non-contact DVRT's housing form its sensing and compensation elements. When the face of the transducer is brought in close proximity to a ferrous or highly conductive material, the reluctance of the sense coil is changed, while the compensation coil acts as a reference.

The coils are driven by a high-frequency sinewave excitation, and their differential reluctance is measured using a sensitive demodulator. Differencing the two coils' outputs provides a sensitive measure of the position signal, while cancelling out variations caused by temperature.

Ferrous targets change the sense coils' reluctance by altering the magnetic circuit's permeability; conductive targets (such as aluminum, see graph) operate by the interaction of eddy currents induced in the target's skin with the field around the sense coil.


	Measurement range NC-DVRT-0.5 NC-DVRT-1.0 NC-DVRT-1.5 NC-DVRT-2.5	0.5 mm 1.0 mm 1.5 mm 2.5 mm
	Nonlinearity	exponential output
	Sensitivity	5 volts/mm typical
	Signal to noise	Standard - 1000 to 1 with filter 3 dB down at 1 KHz
	Resolution	0.1% minimum
	Frequency response	800 Hz standard, 20 KHz optional
	Temperature coefficient	offset 0.0039%/°C (typical) span 0.016%/°C (typical)
	Repeatability	±2 urn typical (at constant temperature)

Mechanical Specifications


	Size NC-DVRT-0.5 NC-DVRT-1.0 NC-DVRT-1.5 NC-DVRT-2.5	diameter x length (thread) 2.84 mm x 8.4 mm (4-40 UNC-2A) 4.83 mm x 19.0 mm (10-32 UNF-2A ) 6.35 mm x 19.0 mm (V4-28 UNF-2A) 12.70 mm x 19.0 mm (V2-20 UNF 2A)
	Housing material	300 series stainless steel
	Fixturing method	threaded stainless nuts
	Leadouts	45 cm, shielded, teflon insulated
	Strain Relief	Stainless wire reinforced multistrand conductors
	Connector	Lemo 4-pin male with shrink polyolefin covering
	Operating temperature	-55 to 175 °C

transducer

ferrous or

conductive

target


	Non-Contact DVRT Calibration
	target: aluminum

U.S. Patent No. 4,813,435 and Patents Pending

NC-DVRT-0.5 can only be used with DEMOD-DVRT - it is not compatible with DEMOD-DC2.

-a o E

1 2

Relative Position (mm)

DVRT is a trademark of MicroStrain Inc. Specifications are s Updated May 4, 2007

without notice.

non-contact displacement sensor - MicroStrain - #2

Displacement sensor, MEMS, LVDT, Signal conditioner, Wireless network