RDP DR7AC Manuale utente

RDP CUSTOMER DOCUMENT

Technical Manual

TRANSDUCER AMPLIFIER

TYPE DR7AC

Doc. Ref CD2402M

Affirmed by Declaration

of Conformity

USA & Canada

All other countries

RDP Electrosense Inc.

RDP Electronics Ltd

2216 Pottstown Pike

Pottstown, PA 19465

U.S.A.

Grove Street, Heath Town,

Wolverhampton, WV10 0PY

United Kingdom

Tel (610) 469-0850

Fax (610) 469-0852

Tel: +44 (0) 1902 457512

Fax: +44 (0) 1902 452000

E-mail [email protected]

www.rdpe.com

E-mail: [email protected]

www.rdpe.com

I N D E X

1. INTRODUCTION................................................................................................ 3

1.1 Certificate of EMC conformity....................................................................... 4

2. INSTALLATION INSTRUCTIONS...................................................................... 5

2.1 EMC Requirements...................................................................................... 5

2.2 Unit Mounting ............................................................................................... 5

2.3 Connections General.................................................................................... 6

2.4 Internal Controls........................................................................................... 6

2.5 Transducer connections (LVDT and half bridge).......................................... 7

3. CONTROLS ....................................................................................................... 8

3.1 Voltage/Current Output................................................................................. 8

3.2 Coarse Gain Selection.................................................................................. 8

3.3 Fine Gain (On front panel, labelled GAIN).................................................... 8

3.4 Coarse Zero.................................................................................................. 8

3.5 Zero Input..................................................................................................... 9

3.6 Fine Zero (On front panel, labelled ZERO)................................................... 9

3.7 Over-Range Indicator................................................................................... 9

3.8 Excitation Voltage......................................................................................... 9

3.9 Excitation Frequency.................................................................................... 9

3.10 Master/Slave................................................................................................. 9

4.0 SETTING UP PROCEDURES.......................................................................... 10

4.1 LVDT & Half Bridge (Differential Inductance) Transducers ........................ 10

5. SPECIFICATION.............................................................................................. 11

6WARRANTY AND SERVICE............................................................................ 12

TABLE OF FIGURES

Fig. 1 Connections.................................................................................................. 6

Fig. 2 Internal Controls........................................................................................... 6

Fig. 3a LVDT transducer connections................................................................... 7

Fig. 3b Half bridge (differential inductance) transducer connections. ................... 7

Fig 4. Excitation Frequency.................................................................................... 9

Fig 5. Master/Slave Connections............................................................................ 9

1. INTRODUCTION

The DR7AC is a single channel signal-conditioning unit for use with transducers requiring

AC excitation and synchronous demodulation, producing a DC output voltage or current.

The DR7AC incorporates a DC-DC converter ensuring that the output of the unit is

electrically isolated from the supply.

Units may be master-slaved in systems where carrier frequency beating is a problem.

The unit is housed in a DIN-rail mounting thermoplastic case with recessed screw-clamp

terminals for all connections and 25-turn front-panel-accessible span and zero

adjustments.

All other controls are internal including coarse gain and zero switches, a zero input switch

and jumper links for master/slave setting and excitation frequency setting.

The unit is suitable for use with the complete range of RDP LVDT transducers.

1.1 Certificate of EMC conformity

DECLARATION OF CONFORMITY

RDP ELECTRONICS LTD.

Grove Street, Heath Town

Wolverhampton, West Midlands

WV10 0PY

United Kingdom

We declare that the product described in this technical manual is manufactured by

RDP Electronics Limited and performs in conformity to the following:

The Electromagnetic Compatibility Directive 2014/30/EU

RoHS2 Directive 2011/65/EU

R D Garbett

Director

RDP Electronics Limited

2. INSTALLATION INSTRUCTIONS

2.1 EMC Requirements

For optimum EMC performance use shielded multi-core cables 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) Pin 5 –Transducer cable

(b) Pin 15 –Supply/Output cable

The DIN-rail to which the unit is attached should be earthed.

The screw clamp terminals can accept either solid or stranded wire sizes from 0.2 mm (24

AWG) to 2.5 mm (12 AWG).

NOTES:

1. Cable shields to be grounded at only one end - the DR7AC end, although grounding

at both ends may reduce the effects of high frequency EMI.

2. When the DR7AC is a small part of a large electrical installation, ensure the cables

to and from the DR7AC are segregated from electrically noisy cables.

3. Ensure cables to and from the DR7AC 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 Unit Mounting

The DR7AC housing is a standard DIN rail enclosure which can clip directly to a 35 mm

top hat rail. The units can be mounted side by side if in an ambient temperature up to

40C. Above this temperature, a gap of 15 mm should be left in between each unit.

2.3 Connections General

Transducer, supply and output connections are

made by 4 x 4 way screw-clamp terminals as

shown in Fig 1.

To reverse output polarity, reverse signal

hi/signal lo. Voltage output is between Volts Out

and common, current output is between current

out and common. Output common is internally

connected to Excitation Lo.

WARNING: INCORRECT SUPPLY

CONNECTION, e.g. CONNECTING SUPPLY

WIRE TO OUTPUT (O/P) MAY DAMAGE THE

UNIT AND INVALIDATE THE WARRANTY.

Fig. 1 Connections

Excitation Hi

Excitation Lo

Signal Lo

Signal Hi

Screen

Master

Slave

m/s comm

Volts Out

Common

Current Out

Supply +

Supply -

Screen

N/C

2.4 Internal Controls

To access internal controls the front part of the DR7AC case needs to be removed. To do

this, use a small screw driver to gently press in the clips behind terminal 1-4 and 13-16. At

the same time pull forward the front of the case. The front of the case and pcb assembly

should now slide forward.

It will usually only be necessary to make changes to Gain and Zero controls.

Fig. 2 Internal Controls

To put case back together, gently slide pcb assembly into case guide slots. Ensure pcb

earth pad CG1 is lined up with the earth clip inside the case, and push back until the front

of the case clicks back into place.

Jumper J1

Exc. Freq.

Jumper J3, Exc. Volt.

Jumper J2

Master/Slave

Location for

Bridge

Completion

Resistors

Coarse

Gain

Control

Coarse

Zero Control

& Zero Input

Switch

Primary Input 1

(Excitation High)

Primary Input 2

(Excitation Low)

Secondary Output 1

(Signal High)

Secondary Output 2

(Signal Low)

PRIMARY

COIL

SECONDARY

COIL

Shield

Excitation High

Shield

Excitation Low

Signal High

2.5 Transducer connections (LVDT and half bridge)

Fig. 3a LVDT transducer connections.

See fig. 1 for pin designations.

Most RDP LVDT transducers also have a BLACK wire. This is not required with the

DR7AC amplifier and should be insulated and left unconnected.

If the above configuration does not give the required output phase (i.e. the output rises

for outward transducer movement instead of falling); reverse signal high and signal low

connections.

Fig. 3b Half bridge (differential inductance) transducer connections.

In addition to these connections, it is necessary to add two bridge completion resistors

to compensate for the fact that the transducer is only half bridge. For RDP transducers,

the resistors should be 1k Ohms, high stability. These should be mounted in R11 and

R12 locations, as shown in Fig. 2.

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 excitation high and excitation low wires will correct this.

3. CONTROLS

(For locations, see Figure 2)

3.1 Voltage/Current Output

Voltage output is available between pins 9 & 10 (common). Current output is available

between pins 12 and 11 (common). Pins 10 and 11 are internally connected.

3.2 Coarse Gain Selection

Typically, transducer manufacturers' data sheets or calibration certificates will give a figure

allowing the full-scale output to be calculated. Possible formats for this are as follows; the

examples assume a transducer range of ±50mm.

Sensitivity format

Explanation

To convert to F.S. output

mV/V/mm

e.g. 46mV/V/mm

Millivolts of output, per volt of

excitation, per mm of travel

Sensitivity x 1 x range in mm

e.g. 0.046 x 1 x 50 = 2.3V

V/V at full-scale,

e.g. 2.3 V//V

Volt of output, per volt of

excitation, at full-scale

Sensitivity x 1

e.g. 2.3 x 1 = 2.3V

mV/mm at a specified

excitation voltage.

E.g. 230mV/mm at 5V exc.

Millivolts of output, per mm of

travel, given a specified

excitation voltage.

(Sensitivity / specified excitation

voltage) x 1 x range in mm

e.g. (0.230/5) x 1 x 50=2.3V

The standard excitation of the DR7AC is 1V, as used in the calculations above.

The following table shows the band of transducer full-scale output voltages appropriate to

each of the 8 Gain Range Settings. For example, a transducer with a full-scale output of

2.3V would be correctly set as gain range 3.

An 4-way toggle switch, SW1, sets the overall gain in the ranges shown below:

SW1

toggles

Gain

Range

Gain Range

(Approximate)

Recommended Input

For ±5V O/P

For 4-20mA O/P

For ±10V O/P

X0.07 to 0.25

4V max

1+2

0.25 to 0.7

4V max

1+3

0.7 to 2.5

2-4V max

1.7-4V max

4V max

1+4

2 to 6

0.8-2.5

0.7-2

1.6-4V max

NONE

5 to 20

0.3-1

0.22-0.8

0.6-2

17 to 50

0.1-0.3

0.07-0.25

0.2-0.6

50 to 170

0.03-0.1

0.02-0.08

0.06-0.2

170 to 500

0.01-0.03

0.02-0.06

3.3 Fine Gain (On front panel, labelled GAIN)

A screwdriver-adjusted, 25-turn potentiometer providing a 4:1 adjustment of gain,

interpolating between the ranges set by the GAIN RANGE switch.

3.4 Coarse Zero

A 5-way toggle switch, SW2, (toggle 6 –see section 3.5) provides output zero shifts of

about 1V per step (with Fine Gain at minimum –up to 4V at maximum). When used with

FINE ZERO will suppress any output (up to 5V) to zero. All toggles OFF is normal, ie no

suppression applied. Switching toggle 1 ON with toggles 3, 4 or 5 will suppress positive

outputs. Switching toggle 2 ON with toggles 3, 4 or 5 will suppress negative outputs. The

suppression increases when toggles 3, 4 or 5 are switched ON.

3.5 Zero Input

SW2 toggle 6 which, when switched to ON, zero’s the signal, input voltage to the amplifier

irrespective of transducer position. This enables a true amplifier zero to be realised.

3.6 Fine Zero (On front panel, labelled ZERO)

A screwdriver-adjusted, 25-turn potentiometer allowing adjustment of output zero by ±1V

to ±4V depending on Fine Gain setting. Used with 3.3 will provide up to 100%

suppression.

3.7 Over-Range Indicator

A red lamp that indicates when the demodulator input exceeds the linear range.

3.8 Excitation Voltage

Units are normally supplied with 1V excitation. This can be changed to 3V by changing J3

to B-C.

3.9 Excitation Frequency

Fig 4. Excitation Frequency

3kHz

5kHz (Factory setting)

If necessary, excitation

frequency can be changed

by moving J1 as shown.

Figure 2 shows the location

of J1.

Other excitation frequencies

are available if stated when

ordering.

3.10 Master/Slave

The unit may be configured as a master oscillator or slave oscillator by the setting of J2.

For Master oscillator (Factory Default) link J2 B-C

For Slave units link J2 A-D

Link terminal 6 on the MASTER unit with terminal 7 on the SLAVES and link terminal 8 on

all units as shown below:

Fig 5. Master/Slave Connections

SLAVE (S)

MASTER

See Fig 2 for the

location of J2

4.0 SETTING UP PROCEDURES

4.1 LVDT & Half Bridge (Differential Inductance) Transducers

4.1.1 Determine the transducer full scale output from the manufacturer's data sheet and

set the Coarse Gain control as shown in Sections 3.

4.1.2 Connect the transducer to the 4-way connector as detailed in Section 2. Switch ON

power and allow a 15-minute warm-up period (for maximum accuracy).

4.1.3 Switch on the ZERO INPUT switch (SW2 toggle 6) and adjust the ZERO controls on

the DR7AC for either 0 volts or 12 mA output (depending on which output is being used).

Switch off the ZERO INPUT switch.

4.1.4 Adjust the transducer armature for either 0 volts or 12 mA output from the DR7AC.

The FINE ZERO control may be used to obtain an absolute zero indication if the armature

adjustment is too coarse.

Now proceed with either 4.1.5 or 4.1.6 according to application.

4.1.5 Bipolar Operation (e.g. ±5V or 4-20mA)

(a) Move the transducer armature by a precise amount (e.g. 5mm for a D6/05000

transducer) and adjust the FINE GAIN control for the desired output, e.g. 5V, or 20mA.

(b) Relocate the transducer armature at the centre of the stroke and check that the

output is zero. Re-adjust the FINE ZERO control if necessary.

Repeat (a) and (b) for consistent results.

example -5v or 4mA output.

4.1.6 Unipolar Operation (e.g. 0 to 10V)

If it is required that the transducer be used over its entire working range in the one

direction, e.g. 0 to 10mm for a D6/05000 transducer, then the zero controls are used to

"back-off" the signal equivalent to 5mm, then:-

(a) Set up as in 4.1.5, i.e. ±5V output for ±5mm using a D6/05000.

(b) Move the armature by exactly 5mm(for a D6/05000transducer) and then adjust the

ZERO controls to back off this signal to zero. Now move the armature back 10mm

and adjust the FINE GAIN control for the required output.

is changed, restart the whole procedure.

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