Cooper Instruments DCM482 Installation Manual

DCM 482

LVDT SIGNAL CONDITIONING

MODULE

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DCM 482/2004

TABLE OF CONTENTS

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

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

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

2.2 Connections General ................................................................................................ 1

2.3 Typical supply/output connections ............................................................................ 3

2.4 Transducer connections (LVDT and half bridge)................................................. 4

3. CONTROLS .............................................................................................................. 6

3.1 Voltage/Current Output ............................................................................................ 6

3.2 Coarse Gain Selection .............................................................................................. 6

3.3 Fine Gain ................................................................................................................ 6

3.4 Coarse Zero ............................................................................................................. 7

3.5 Zero Input ............................................................................................................... 7

3.6 Fine Zero................................................................................................................. 7

3.7 Over-Range Indicator............................................................................................... 7

3.8 Excitation Frequency................................................................................................ 7

3.9 Master/Slave............................................................................................................ 7

4.0 SETTING UP PROCEDURES ................................................................................ 8

4.1 LVDT & Half Bridge (Differential Inductance) Transducers....................................... 8

5. SPECIFICATION ....................................................................................................10

6 WARRANTY AND SERVICE................................................................................... 11

DCM 482/2004 ii

1. INTRODUCTION

The DCM 482 is a signal-conditioning unit for use with transducers requiring AC excitation and
synchronous demodulation, producing a DC output voltage or current. Units may be master-slaved in
systems where carrier frequency beating is a problem.

The unit is housed in a robust aluminum case with connections via glands, all sealed to IP65
specification. All controls are internal with coarse range switches and fine adjustment potentiometers
for gain and zero setting. Other controls include a zero-input switch, over range indicator and pin­mounted components for frequency changing and half-bridge operation.

The unit is suitable for use with the complete range of Cooper Instruments & Systems LVDT
transducers.

2. INSTALLATION INSTRUCTIONS

2.1 EMC Requirements

For full EMC compliance, only shielded multi-core cables should be used for connection to this
instrument; the cable shield may be terminated by means of a short "pig-tail" and connected to the
terminals marked:

(a) SCN - for transducer cable
(b) GND - for supply/output cable

With units to Mod.7 onwards status, with metal glands, for optimum EMC the shields should be
terminated as shown in Fig.2 (b).

The metal case should be grounded. This would usually be achieved by the use of fixing bolts
through the case mounting holes into the (grounded metal) surface the DCM 482 is mounted on.

NOTES:

1. Cable shields to be grounded at only one end - the DCM 482 end, although earthing at both
ends may reduce the effects of high frequency EMI.

2. When the DCM 482 is a small part of a large electrical installation, ensure the cables to and
from the DCM 482 are segregated from electrically noisy cables.

3. Ensure cables to and from the DCM 482 are routed away from any obviously powerful sources
of electrical noise, e.g. electric motor, relays, solenoids.

4. ESD precautions should be used when working on the instrument with the lid removed. The
user should ensure he is "grounded" by use of an earthed wrist strap or at least touching earth
before touching any component including wires, terminals or switches.

5. The transducer body should be grounded. Some transducers such as LVDTs, load cells, etc.
without an internal body-to-shield connection, require a separate earth. This should preferably
be connected to the instrument shield terminal or as near (electrically) as possible to this point.

2.2 Connections General

Transducer and supply/output connections are made via two screw-clamped terminal blocks mounted
on the circuit board adjacent to the two cable glands as shown in Fig.1.

DCM 482/2004 1

To reverse output polarity, reverse Signal Hi/Signal Lo. With all supplies, voltage output is between
OUTPUT and COMMON, which is internally connected to Excitation Lo and Shield. For best results,
COMMON should be grounded. NEVER CONNECT COMMON TO V+ OR V-.

Note that when using single supply, the output common is referenced to approximately half the supply
voltage and should be monitored with a floating or differential input instrument with sufficient common
mode voltage range.

Current (4-20mA) output is between OUTPUT and V-.

WARNING: INCORRECT SUPPLY CONNECTION, e.g. CONNECTING SUPPLY WIRE TO
OUTPUT (O/P) MAY DAMAGE THE UNIT AND INVALIDATE THE WARRANTY.

Fig. 1 Control locations etc.

The G'ND terminal is connected to the case.

DCM 482/2004 2