LDM-1000DIN Rail Mount LVDT Conditioner

Operation Manual

LDM-1000 Din Rail Mount LVDT Conditioner

WarrantySchaevitz instruments are warranted during a period of one year form date of shipment to original purchaser to be free from defects in material and workmanship. The liability of Seller under this warranty is limited to replacing or repairing any instrument or component thereof which is returned by Buyer, at his expense, during such period and which has not been subjected to misuse, neglect, improper installation, repair, alteration, or accident. Seller shall have the right to final determination as to the existence and cause of a defect. In no event shall Seller be liable for collateral or consequential damages. This warrant is in lieu ofany other warranty, expressed, implied, or statutory; and no agreement extending or modifying it will be binding upon Seller unless in writing and signed by a duly authorized officer.

Receiving InspectionEvery Schaevitz instrument is carefully inspected and is in perfect working order at the time of shipment. Each instrument should be checked as soon as received. If the unit is damaged in any way, or fails to operate, a claim should immediately be filed with the transportation company.

Service ConcernsIf a Schaevitz instrument requires service, first contact the nearest Schaevitz Representative. He may be able to solve the problem without returning the unit to the factory. If it is determined that factory service is required, call the Repair Department for an RMA number before return.

ReturnsAll units being returned to the factory require an RMA (Return Material Authorization) number before they will be accepted. This number may be obtained by calling the Repair Department at 1-800-745-8008 with the following information: model number, quantity, serial number, and symptoms of the problem, if being returned for service. You must include the original P.O. number or Schaevitz sales number if under warranty.

InquiriesAddress all inquiries on operation or applications to your nearest Sales Representative, or to Sales Manager, Schaevitz Sensors, 1000 Lucas Way, Hampton, VA 23666, USA.

Table of Contents

1

Product Description 2

Specifications 2

Controls, Adjustments and Indicators 4

Internal Jumper 5

Wiring 6

Gain Selection 9, 10

Calibration 10, 11

2

Product Description

The LDM-1000 LVDT DIN rail mount signal conditioner module is a DC-powered LVDT signal conditioner. The modulesupplies AC sine wave excitation to the LVDT and then demodulates and amplifies the LVDT output. A full-wavesynchronous demodulator minimizes quadature output and maximizes noise rejection. The module consists of a carrieroscillator, AC amplifier, demodulator, filter and DC amplifier. The LVDT excitation frequency is factory pre-set to 2.5 kHz.A 5 and 10 kHz, excitation is available by use of internal DIP switches. The factory default setting for LVDT drive is 3 Voltsrms. An internal switch may be used to select 1 Volt rms. drive, for LVDTs with low primary impedance or full scale outputsexceeding the maximum FSO on the page 9 gain table. A 1-Volt drive must also be used when operating the LDM-1000 in thelow voltage mode.

Seven gain ranges are available to provide position output signals of ± 5Vdc, 0-5Vdc or 0-10Volts dc., for LVDT full-scalesignals ranging from 50 mV. rms. to 2.5 Volts rms. Gain and output ranges are selectable by internal DIP switches. A spantrimmer potentiometer is provided for precise control within each gain stage. Internally selectable master/slave function allowssynchronization of multiple LDM-1000 modules to prevent beat frequencies and cross talk between transducers.

A zero trimmer potentiometer provides fine correction for zero offsets.

The LDM-1000 module operates with 4, 5 or 6 lead LVDTs and RVDTs.

The LDM-1000 is designed to be mounted to a standard number 3 DIN rail. The module is 22.5mm wide, 99mm high and114.5mm deep. Input/output connections are made through plug-in screw terminal barrier strips. These plug-in strips arekeyed to prevent improper connections in the unlikely event that the LDM-1000 should require field replacement.

Installation

In order to configure the LVDT DIN mounted signal conditioner, you must access the internal dip switches.The front panel may be slid out to gain access.

To open the housing, depress the two latches, (see photos below), with a screwdriver, the housing will spring open. You cannow slide the front panel and PC board assembly forward to access the dip switches and input voltage jumper.

After approximately 4 cm of extension, a spring stop will prevent the PCB from being removed completely and, will lock it inplace. The module may be configured easily from this position.

3

Specifications

Transducer ExcitationVoltage 3.0 or 1.0 Vrms nominal (switch selectable)

(3.0 V only available with +24V input)Frequency 2.5 kHz, 5.0 kHz and 10.0 kHz (switch selectable)Current 25 mA. rms.

Voltage OutputOutputs ± 5, 0 to +5 and 0 to +10 Vdc (5 mA. max)Noise and ripple Less than 3 mV. rms.

Current Output 4 to 20 mA. dc (requires minimum +24V input)Loop Resistance 700 ohms maxNoise and ripple Less than 20 µA. rms.

Frequency Response 250 or 1000 Hz (switch selectable)(-3 dB point ) (3-Pole Butterworth filter)

Sensitivity .050 to 2.0 Volts rms. input, for FS analog outputFixed Ranges 7 (switch selectable)Adjustable 2.5 to 1 (Screwdriver adjustable)

Zero AdjustmentFixed Steps +20% and -20%Adjustable ± 10% (Screwdriver adjustable)Total Range ±30%

Non-linearity (typical) Less than 0.02% of full scaleTemperature Coefficient 0.04% of full scale / °C Max.

Operating Temperature -25°C to +85°CStorage Temperature -50°C to +105°C

Input Power Requirements+24 ± 6 Vdc @ 65 mA max.

+14 ± 4 Vdc @ 45 mA max. (Jumper JP-1 In)

Mounting Standard DIN-3, rail mount

Size 22.5 mm wide x 99 mm high x 114.5 mm deep

Wire Termination Plug-in, keyed screw terminal strips24 to 12 AWG wire (0.2 to 2.5 mm.)

4

Controls, Adjustments and Indicators

Front Panel ControlsSpan: Sets the full-scale output of the amplifier to the desired voltage or current.Phase: Optimizes amplifier demodulation to compensate for cable or LVDT induced phase shift.Zero: Sets the zero position or offset.

Front Panel IndicationsPwr. LED: Indicates when DC power is applied.Loop LED: Indicates when loop current is flowing. LED intensity is proportional to the amplitude of the signal.

Internal SwitchesThere are two internal dip switch sets on the LDM -1000 LVDT signal conditioner. The tables below explain the

switch positions and functions.

Switch SW-1Switch Number 1 2 3 4 5 6 7 8

Function Offset Signal Bandwidth Gain 2 Gain 1On Pos Neg 1000 Hz 1000 Hz 1000 Hz LowOff Off Off 250 Hz 250 Hz 250 Hz High

X4.43 All Switches Must Be On OnX3.63 In The Same Position On OffX1.2 Off OnX0.4 Off Off

Switch SW-2Switch Number 1 2 3 4 5 6 7 8

Function Osc Freq Sync Osc. V None Desired Output (V-dc.)On INT 1 V NOT 0 to 5 ± 5 0 to 10Off EXT 3 V USED Only One On

10 kHz On On 4 to 20 Works With Any Setting5 kHz Off On

2.5 kHz Off Off

The default settings as shipped are 2.5 kHz Excit Freq, INT Sync, 3 V Excit, ±5V Output Voltage, no Offset, 250 Hz SignalBandwidth, and HIGH X0.4 Gain (Sensitivity from 0.78 to 1.20 Vrms). Switches SW2-3 is ON to select INT Sync and SW2-7 is ON to select ±5V Output Voltage. All other switches are OFF.

5

Internal Jumper

The rated input voltage is +18 to +30 volts dc, with JP-1 in the storage position. The operating voltage may be changed to +10to +18 volts dc, by installing internal jumper JP1 across both pins. The LDM-1000 is shipped with the jumper installed in thestorage position. See the diagram below.

Note: Operating the unit at voltages above +18 volts with the jumper in the low voltage position will overheat the internalvoltage regulators and reduce the operational life of the LDM-1000.

6

Wiring

The input/output connectors are four position, indexed, plug-in screw terminal barrier strips. Once all of the connections aremade, the LDM-1000 conditioner may be removed and reinstalled without disconnecting the individual wires. The wireclamps are designed to accept AWG-24 to AWG-12 sized stripped and tinned wires with no soldering required.

Input

The primary and secondary leads of the LVDT connect to P-1. The cable shields, connect to P-2. The LDM-1000 is a four-wire LVDT signal conditioner and does not require connection of the center tap to the input connector. The center tap wires,usually blue and green, of six wire LVDTs must be connected together. For best performance, center taps should always beconnected as close to the transducer as possible, see figures 2, 3 and 4.

Twisted, separate shielded, two pair cable such as Belden 8723 or equivalent is recommended for the LVDT input wiring.

Outputs

The voltage output position signal is wired to P3. The 4-20 mA current position signal is wired to P4, see fig 2.

Power

The input power, to operate the LDM-1000, is wired to P4, see fig 2.

Master/Slave Wiring

To synchronize the carrier frequencies of two or more instruments, pin 11 and 12, of the master, should be tied to 11 and 12 ofeach slave. SW2-3, must be placed in the on or INT position, on the instrument selected as the master. All of the LDM-1000slaves must have SW2-3 in the off or EXT position.Caution: Connecting the Sync terminal, pin 11 of P3, of two units with INT sync selected (SW2-3 on) may result in damage tothe units, see fig 2.

General

For outside installations or cable lengths greater than 30m external surge suppression should be provided by the end user toensure continued compliance with EMC directives.

Oscillator Voltage Selection

The default setting as shipped for the oscillator voltage is 3V. The maximum oscillator output current is 25 mA. rms. Thus forthe 3 V oscillator output, the minimum load impedance is 120 ohms. If the primary impedance of the LVDT being used is lessthan 120 ohms at the selected oscillator frequency, the 1 V oscillator output must be used. Similarly, the minimum loadimpedance for the 1V oscillator output is 40 ohms. If the primary impedance of the LVDT being used is less than 40 ohms atthe selected oscillator frequency, try using a higher frequency if possible.

If the full scale output of the LVDT is greater than 2.5 V. rms. reduce the primary excitation to 1 V. If the full scale output isless than 0.05 V rms., increase the primary excitation to 3 V.

7

8

9

Gain Selection

The LVDT full-scale output is given by the following equation:

LVDT F/S output voltage = Sensitivity X Primary Voltage X Full Scale Displacement

where the LVDT FS output is in V. rms.

Sensitivity is in either mV/V/.001" or mV/V/mm. The sensitivity can be found either in the manufacturercatalog or on the LVDT's data sheet.

Full Scale Displacement is the plus / minus linear range of the LVDT, from the center zero null position.The full stroke, or operating range of the LVDT, is two times the full scale. It is measured in thousandth ofan inch or in mm depending on the units of the sensitivity. The units of the sensitivity and full-scaledisplacement must agree. They must both be in inches or in mm.

The primary voltage is either 3 Vrms or 1 Vrms as set by switch SW2-4.

Once you know the LVDT full scale output, the gain may be selected from the chart below:

Gains Switch PositionsGainNumber

For LVDT Full ScaleOutput In V rms.

From ToGain 1 Gain 2 Switch 1-6 Switch 1-7 Switch 1-8

1 1.20 2.50 X 0.4 Low On Off Off2 0.78 1.20 X 0.4 High Off Off Off3 0.40 0.78 X 1.2 Low On Off On4 0.26 0.40 X 1.2 High Off Off On5 0.13 0.26 X 3.63 Low On On Off6 0.10 0.13 X 3.63 High Off On Off7 0.05 0.10 X 4.4 High Off On Off

Examples:

If you are using a 050 HR at 2.5 kHz over its full stroke, what settings do you use?

From the catalog, the 050HR is specified at 2.5 kHz, so the oscillator frequency is set to 2.5 kHz. Switches SW2 -1and -2 should be set to OFF.Select 3V as the oscillator amplitude. Switches SW2-4 should be set to OFF. The primary impedance of the 050 HRat 2.5 kHz is 430 ohms so the current is 3 / 430 = 7 mA. This is well under the maximum allowable current so we cancontinue.

Again from the catalog, the sensitivity of the 050 HR at 2.5 kHz is 5.8 mv/V/.001". The full-scale output is 5.8 x 3 X50 = 870 mV or 0.87 V. From the above chart the desired gain is gain number 2 (X0.4 High). Switches SW2 -6, -7and -8 should all be set to OFF.

10

If a 250XS-ZTR is being used at 2.5 kHz over a 10mm (±5mm) full stroke, what setting do you use?

From the catalog, the 250XS-ZTR is specified at 2.5 kHz, so the oscillator frequency is set to 2.5 kHz. Switches SW2-1 and -2 should be set to OFF.Select 3V as the oscillator amplitude. Switch SW2-4 should be set to OFF. The primary impedance of the 250XS-ZTR at 2.5 kHz is 100 ohms so the current is 3 / 100 = 30 mA. This exceeds the maximum current limit of the LDM-1000. Reduce the excitation voltage to 1 V. Switch SW2-4 should be set to ON.At 1 V excitation, the primary current is 1 / 100 = 10 mA. This is well under the maximum allowable current so wecan continue.

Again, from the catalog the sensitivity of the 250XS-ZTR at 2.5 kHz is 12 mV/V/mm. The full-scale output is 12 X 1X 5 = 60 mV or .060 Volts. From the above chart the desired gain is gain number 7 (X4.3 High). Switches SW2 -6, -7 and -8 should be all be set to OFF, ON and OFF respectively.

Calibration

The first step is to zero the electronics. To do this we need to remove the input signal. This is best achieved by disconnectingthe high side of the primary, (P-1), as close to the LVDT as possible. This will allow you to correct for any zero shift causedby the cable.

Using the ZERO control on the front panel, adjust until the output reads in the center of the scale.0.0 Vdc for ± 5 Vdc Output2.5 Vdc for 0 to +5 Vdc Output5.0 Vdc for 0 to +10 Vdc Output12.0 mA for 4 to 20 mA output

Next, we zero the LVDT by finding its electrical null point. Reconnect the LVDT primary, (P-1 position 1). Move the coreconnecting rod or plunger of the LVDT until the output reads the center of the scale (same reading as above for electroniczero). The core of the LVDT should now be approximately in the center of the LVDT. This is the null position of the LVDTfrom which the plus and minus displacements are measured.

NOTE: If this adjustment is mechanically difficult or impractical, approximate the correct position as closely as possible andthen turn the ZERO control to obtain a zero reading.

Next, adjust the phase of the of the reference signal for the demodulator. Using the connecting rod or plunger, move the coretoward the lead or connector end of the LVDT approximately 70 to 80% of the plus full-scale displacement.

NOTE: Positive full scale displacement for an LVDT is the maximum rated displacement of the core into the LVDTfrom the null position toward the lead exit or connector end of the LVDT. This should result in a positive outputfrom the LDM-100. To reverse the output polarity, interchange the secondary connections on terminals 3 and 4 ofP1.

This part of the calibration does not have to be precise. Adjust the front panel PHASE control in the direction to increase theoutput the signal. Continue to adjust the PHASE control until the output peaks, that is the position where the output decreasesregardless of the direction the PHASE control is turned. If the output does not peak and the PHASE control is at the end of itsadjustment, leave it there and continue with the calibration.

11

If at any point during the phase adjustment the output exceeds the maximum output limit of the selected range, reduce thesignal output back to a 70-80% level by adjusting the front panel SPAN control. Then continue with the phase adjustoperation.

Return the core back to the original zero position (LVDT null position). It should still be the center of the range (the samereading as above). If not, make a small adjustment with the ZERO control.

Displace the core towards the leads exactly plus full scale, using a micrometer, gage blocks, or other displacement standard.This position should be the maximum positive full-scale range over which you intend to operate.

Note: The calibration can be made over some percentage of full scale by moving the core xx% of full scale andadjusting the output for the same percentage output, as well.

Using the front panel SPAN control, adjust the conditioner for full scale output (usually the maximum output limit of theselected range.

5.0 Vdc for ± 5 Vdc Output5.0 Vdc for 0 to +5 Vdc Output10.0 Vdc for 0 to +10 Vdc Output20 mA for 4 to 20 mA output

If the required full-scale reading cannot be obtained by adjusting the SPAN control, the gain of the signal conditioner can bereset by changing the internal jumpers. If the SPAN control is fully counter clockwise, change the gain switches SW2-6, -7and -8 to the next higher gain. If the SPAN is fully clockwise, change the gain switches to the next lower gain.

Recheck the zero at the LVDT null point. You may displace the core full-scale displacement away from the leads (minus fullscale) to check for symmetry. The output reading should be the minimum output limit of the selected range. For unipolaroutputs, the minus full scale can be trimmed with the ZERO control and the positive full scale trimmed with the SPAN control.For bipolar outputs, it is generally desirable to keep the center point at zero with the ZERO control and balance the plus andminus outputs with the SPAN control.

North American OperationsSchaevitz Sensors1000 Lucas Way

Hampton, VA 236661-800-745-8008757/766-1500

FAX: 757/766-4297

European OperationsSchaevitz Sensors543 Ipswich Road

Slough, Berks SL1 4EGEngland

Phone: +44 (0) 1753537622Fax: +44 (0) 1753823563

P/N 09290100-000

72

LVDT Accessories

LVDT Mounting Blocks Core Connecting RodsLVDT installations require aconnecting rod between theLVDT core and the objectwhose motion is beingmeasured. These connectingrods are fabricated fromnon-magnetic stainless steelto prevent distortion of theLVDT’s magnetic field.Manufactured from AISI 300 Series stainless steel, coreconnecting rods are threaded end to end. (Consult factoryfor available lengths and sizes.)

To Order: Specify CCR-(Length)-(LVDT Series)-(S forstandard thread or M for metric thread). For example, toorder a 4" rod to go with an MHR Series LVDT equippedwith the optional metric thread core, specify: CCR-4-MHR-M

Frequently, LVDT installationsrequire a convenient method tomount the units. Ready-mademounting blocks are available forall LVDT Series (except XS-B).Constructed of reinforced phenolicand other nonconductive materialswith a low-temperature coefficientof expansion, mounting blocks are aconvenient, inexpensive and fastsolution for LVDT installation.

To Order: use the chart below to specify the part numberfor the appropriate LVDT Series.

MS-Type Connector CablesConsult factory for price and availability of adaptor cablesfor LVDTs and signal conditioners.

PSD 4-15 DC LVDT Power SupplyThe PSD 4-15 DC LVDT powersupply is designed to work with allof Schaevitz® DC powered LVDTs.The module will operate on either a115 VAC or 230 VAC input at 47 to63 Hz. The PSD 4-15 provides thenecessary ±15 VDC excitation tooperate as many as four DC-EC orHCD Series LVDTs, as well asGCD Series gage heads or DCpowered Schaevitz® RVDTs (seerotary section) or pressure transducers (see pressuresection) that require a ±15 VDC input. The rugged, compactdesign can be chassis mounted and features a DIN standardrail mount for secure installation in most industrialenvironments. In addition, the PSD 4-15 is UL, VDE andcUL approved and CE certified.

General SpecificationsInput Voltage ................... 115/230 VAC ±10%Input Frequency ............... 47 to 63 HzInput Current ................... 0.1 A (max)Output Voltage ................. ±15 VDC ±0.05%Output Current ................ 100 mA continuousRipple ................................ < 5mV. pp.Noise ................................. < 5mV. pp.Overload Protection ........ ContinuousOverall Dimensions ........ 2.00 x 4.31 x 0.90 inches;

(51 x 110 x 23 mm)Operating Temperature .. –25°C to 70°C

0.25(6.35)

0.31(7.87)

0.19(4.83)

0.63(16.0)

0.50(12.7)

1.00(25.4)

1.44(36.58)

2.22(56.39)

1.25(31.75)

0.63(16.0)

0.06 (1.52)�Saw Slot

0.31(7.87) 0.63

(16.0)

Ø 0.169 (4.29)�thru to center� Ø0.281 (7.14)�x 0.188 (4.78)

Ø0.149(3.78)�

2X

8-32UNC - 2B�x 0.38 (9.65)

Dia "A"�(see Table 1)

8-32UNC - 2B�x 0.50 (12.7)�2x

Dimensions in (mm)

LVDT Mounting Blocks

Use with Dim. A LVDTPart Number LVDT Series Diameter Diameter

04560950-000 E 0.77 0.750

04560952-000 HR 0.83 0.812

04560953-000 M 0.33 8 mm

04560954-000 MHR 0.39 0.375

04560956-000 M-12 0.49 12 mm