Omega Products LD340 Installation Manual

Series 956

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Series 956

LD340 Series

AC Miniature LVDT

Displacement Transducers

Servicing North America:

U.S.A.:

Omega Engineering, Inc., One Omega Drive, P.O. Box 4047

ISO 9001 Certified

Stamford, CT 06907-0047
Toll-Free: 1-800-826-6342 Tel: [phone]
FAX: [phone] e-mail: [e-mail]

Canada:

976 Bergar
Laval (Quebec), Canada H7L 5A1
Toll-Free: 1-800-826-6342 TEL: [phone]
FAX: [phone] e-mail: [e-mail]

For immediate technical or application assistance:

U.S.A. and Canada:

Sales Service: 1-800-826-6342/1-800-TC-OMEGA

®

Customer Service: 1-800-622-2378/1-800-622-BEST

®

Engineering Service: 1-800-872-9436/1-800-USA-WHEN

®

Mexico:

En Español: 001 [phone] FAX: [phone]
[e-mail] e-mail: [e-mail]

Servicing Europe:

Benelux:

Managed by the United Kingdom Office
Toll-Free: 0800 099 3344 TEL: [phone]
FAX: [phone] e-mail: [e-mail]

Czech Republic:

Frystatska 184
733 01 Karviná, Czech Republic
Toll-Free: 0800-1-66342 TEL: [phone]
FAX: [phone] e-mail: [e-mail]

France:

Managed by the United Kingdom Office
Toll-Free: 0800 466 342 TEL: [phone]
FAX: [phone] e-mail: [e-mail]

Germany/Austria:

Daimlerstrasse 26
D-75392 Deckenpfronn, Germany
Toll-Free: 0 800 6397678 TEL: [phone]
FAX: [phone] e-mail: [e-mail]

United Kingdom:

OMEGA Engineering Ltd.

ISO 9001 Certified One Omega Drive, River Bend Technology Centre, Northbank

Irlam, Manchester M44 5BD England
Toll-Free: 0800-488-488 TEL: [phone]
FAX: [phone] e-mail: [e-mail]

OMEGAnet®Online Service Internet e-mail

omega.com [e-mail]

It is the policy of OMEGA Engineering, Inc. to comply with all worldwide safety and EMC/EMI
regulations that apply. OMEGA is constantly pursuing certification of its products to the European New
Approach Directives. OMEGA will add the CE mark to every appropriate device upon certification.

The information contained in this document is believed to be correct, but OMEGA accepts no liability for any
errors it contains, and reserves the right to alter specifications without notice.
WARNING: These products are not designed for use in, and should not be used for, human applications.

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LD340 M-5106 02/12

GENERAL

The AC miniature series of 9.5 mm (3/8”) diameter AC operated LVDT’s are; Small Size,
Precision Position Sensors for both OEM’s and End Users. While Ideal for space restrictive
applications, their epoxy bonded construction also make them suitable for operation in *wet or
oily environments and their light weight cores are perfect for dynamic measurement.

* Not suitable for total immersion.

1.1 Introduction

The AC miniature range of transducers operate on the L.V.D.T. principal, where movement of a
core inside the transducer body is detected by a differential change in output on two secondary
coils, the primary coil(s) being energised by an appropriate AC signal. With the core in a central
position, the coupling from the primary to each secondary is equal and opposite and therefore
cancel out, thus the resultant output voltage is zero. As the core is displaced further into one
secondary, its voltage increases proportionally and the other secondary voltage decreases hence
the output changes in magnitude and phase in proportion to movement in either direction from
null.

The red and white connections are in phase for inward movement (ie. towards the cable end).

The output signal depends on both core movement and energisation voltage and is expressed as
a sensitivity in mV output / V energising / mm travel.

1.2 Installation

L.V.D.T. transducers generally are a reliable and proven technology that is well established
in all areas of manufacturing and control industries. The majority of the associated problems
experienced with their application and use are totally avoidable, particularly if sufficient thought
is given during the initial design stages of equipment, to the positioning and clamping methods
employed for these feedback elements.

L.V.D.T.’s being of inductive nature are susceptible to some degree to the influence of magnetic
fields and therefore should be positioned well away from electric motors, relays and permanent
magnets, where this is not possible then magnetic shielding should be considered as an
alternative.

Clamping of the coil assembly should be carefully considered, some example methods are shown
in figure 1. Ideally the body of the transducers should be clamped centrally in a pinch or yoke
type clamp, manufactured from a low conductivity, non-magnetic material, if this is not possible
then the introduction of a non-metallic bush between body and clamp is a preferred alternative.

Irrespective of clamping method care must be taken not to over tighten retaining screws as
distortion of the body may prove damaging to the integrity of the transducer and adversely affect
the geometry of the installation.

If the L.V.D.T. is to be mounted on equipment subject to high ”g” then dependent on the direction
of these forces, it may be advantageous to consider end to end clamping in preference to over
body clamping.

LD340 M-5106 02/12

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