Cooper Instruments DCM480 Installation Manual

DCM 480

LVDT SIGNAL CONDITIONING

MODULE

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DCM 480/2004 1

TABLE OF CONTENTS

1. INTRODUCTION ........................................................................................................ 1

2. INSTALLATION INSTRUCTIONS .......................................................................... 1

2.1 EMC Requirements................................................................................................... 1

2.2 Supply/Output Connections...................................................................................... 1

2.3 Transducer Connections............................................................................................ 2

3. CONTROLS .................................................................................................................. 5

3.1 Coarse Zero Switch................................................................................................... 5

3.2 Fine Zero Potentiometer ........................................................................................... 5

3.3 Zero Input Switch ..................................................................................................... 5

3.4 Span Switch (Coarse gain)........................................................................................ 5

3.5 Fine Span Potentiometer........................................................................................... 6

3.6 Filter Switch.............................................................................................................. 6

4. SETTING UP PROCEDURE............................................................................. 7

4.1 Bipolar or Half-stroke Applications.......................................................................... 7

4.2 Offset Stroke Applications........................................................................................ 7

5. SPECIFICATION......................................................................................................... 8

6. WARRANTY AND SERVICE .................................................................................... 9

DCM 480/2004 ii

1. INTRODUCTION

The DCM 480 is a two-wire, 4-20mA-output oscillator/demodulator for use with LVDT
transducers having suitable primary impedance. (Refer to sect 5).

Coarse and Fine controls for gain and zero (4mA) allow use with the full range of Cooper
transducers and a filter switch allows selection of optimum bandwidth/noise. The
differential signal amplifier circuit allows the use of long transducer cables.

The two-wire supply/output system allows use with long cables from the supply/monitor
with a wide range of supply voltage and high noise immunity.

In order to meet the primary impedance requirements of the DCM 480, some Cooper
transducers are modified to TM202. Section 2.4 refers.

Note: The DCM 480 is not suitable for use with differential or half-bridge transducers.

2. INSTALLATION INSTRUCTIONS

2.1 EMC Requirements

For EMC compliance, good quality shielded cable should be used for connection to this
instrument. The shields of both transducer and 4-20mA loop cables should be

connected as shown in Fig. 4.

• Note 1-Cable shields to be grounded at only one end - the instrument end.

• Note 2-When the instrument is a small part of a large electrical installation,

ensure the cables to and from the instrument are segregated from electrically
noisy cables.

• Note 3-Ensure cables to and from the instrument are routed away from any
obviously powerful sources of electrical noise, e.g. electric motors, relays,
solenoids.

• Note 4-ESD precautions should be used when working on the instrument circuit
board with the lid removed. The user should ensure he is "grounded" by use of a
wrist strap or at least touching ground before touching any component including
wires, terminals or switches.

• Note 5-The body of the transducer and the DCM 480 case should be grounded.
If the transducer fixing attachments do not provide a good ground, then a ground
strap should be used.

2.2 Supply/Output Connections

The two wires from the supply/output monitor are connected to terminals 6 and 7
Polarity of supply is irrelevant as a reverse polarity protection circuit automatically
energises the oscillator/demodulator with the correct polarity.

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.

2.3 Transducer Connections

Fig. 1 General view of DCM 480

Fig. 2 Connection for LVDT Transducers

Function TB1 PIN
Excitation Hi Excit 1
Excitation Lo Excit 2
Signal Hi Signal 3
Signal Lo Signal 4
Shield Gland shell

(see Fig. 4)

Some Cooper LVDTs have a BLACK wire. This
must be insulated.
If when connected, the phase of the amplifier
output is not as required (for example, an
inward moving armature causes a rising
amplifier output when a falling output is
required) then reversing the signal high and
signal low wires will correct this.

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