Kinetrol EL Guide

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05/10/09 Trading Estate Farnham Surrey England Doc. No. TD 76
Page 1 of 12
1. CONTENTS.
Page. Section.
1 1. Contents.
2 2. Installation.
2 2.0 Introduction.
2 2.1 Direct Mounting Units onto Kinetrol Positioner Actuators.
2 2.2 Mounting of Discrete Positioners.
3 2.3 Air and Electrical Connections.
3 2.3.1 Air Supply.
3 2.3.2 DIN Plug Option.
3 2.3.3 Positioner Signal.
4 2.3.4 Angle Retransmit Supply.
4 3. Schematic Functional Diagram.
4 4. Setup.
4 4.0 Introduction.
5 4.1 Setting Travel Speed.
5 4.2 Setting Optional Limit Switch Cams.
5 4.3 Overview – Electronic Settings.
6 4.4 Default Settings and Reset Procedure.
6 4.5 Entering and Leaving Setup Mode.
6 4.6 Automatic Endstop Finding Procedure.
7 4.7 Proportional Gain and Damping Settings.
7-8 4.8 Low Current Point and High Current Point Setting.
8 4.9 Reversing Clockwise/Anticlockwise Sense.
9 4.10 Changing the Direction of Movement on Loss of Signal.
9 4.11 Resetting the Feedback Pot.
9 4.12 EEPROM Checksum Error.
10 4.13 Selecting and Setting Up Non-Linear Curves.
11 4.14 Setting Optional Angle Retransmit Span and Zero Adjustments.
11 4.15 Adjustment of Position of Optional Clearcone Monitor.
12 5. Maintenance and Troubleshooting.
KF 400 – 10/09:INDEX H\Drawing office docs. Master KF WI TD etc.\current TD sheet masters
Title : Installation, Operation & Maintenance Instructions – Digital EL Positioner
NOTE – THIS INSTRUCTION SHEET APPLIES ONLY TO NON INTRINSICALLY SAFE MODELS
WITH DIGITAL POSITIONER CIRCUITS.
IF YOUR APPLICATION IS IN AN AREA WITH AN EXPLOSION HAZARD, DO NOT USE THE
FOUR TERMINAL MODELS DESCRIBED HERE.
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Title : Installation, Operation & Maintenance Instructions – Digital EL Positioner
2. INSTALLATION
2.0 Introduction
Positioners can be supplied direct-mounted, or ready to be direct-mounted, onto Kinetrol rotary actuators, or in stand-
alone (discrete) form for fitting via a mount kit to any 90 degree rotary actuator. If the positioner is supplied ready mounted
on an actuator, sections 2.1 and 2.2 can be bypassed. Positioner-type Kinetrol actuators (ready for direct mounting of
positioners) are available in models 03 to 14 inclusive.
These instructions cover the possible use of both metal and moulded feedback coupling. It is expected that most units
will contain a moulded coupling.
2.1.1 Move actuator vane to mid travel position, with its output square as shown in Figure 1. This is essential to prevent
subsequent error in orienting positioner square.
2.1.2 Remove positioner cover, and undo the five M4 slot-headed screws holding the red plastic carrier plate into the body.
Disconnect the two wires to the servo valve, and lift out the whole carrier plate assembly complete with shaft and circuit etc.
2.1.3 Bolt the positioner body to the actuator in the orientation shown in Figure 1, taking care that O-rings are in place to seal
the ports into the actuator, and that the actuator shaft is centred in its hole.
2.1.4 (a) Metal coupling versions on 07 and larger models: fit anti-backlash spring over one corner of the actuator square as
shown in Figure 2.
(b) Moulded coupling versions: on all direct mount versions, loosen central screw in coupling shaft so that the collet is
not closed, and fit coupling over shaft square.
2.1.5 Observe the range of motion available to the positioner shaft, limited by the correct running of the potentiometer
quadrant wheel, driven by the stainless steel strap (see Figure 3). Fit the carrier plate/shaft assembly back into the positioner
box with the shaft near mid-range, “feeling” the female square in the positioner shaft onto the male actuator square while
maintaining its position near mid range. It is essential that the two shafts are correctly oriented relative to each other, since if
they are 90 degrees out, the quadrant wheel can be forced too far and damage done to the drive mechanism during
subsequent actuator movements. It is possible to fit the positioner correctly with the actuator square at one end of its travel,
but experience indicates a high probability of mistaking the direction of movement of the actuator – hence it is strongly
advised that the positioner be fitted with the actuator square at the mid-travel position, where there is no ambiguity possible.
Moulded coupling version: Ensure coupling is fully engaged before tightening the central screw to close the collet and
therefore removing any backlash.
2.2 Mounting of Discrete Positioner
Design and manufacture of the mount kit between positioner and actuator is outside the scope of this document. It is essential
that the shaft of the actuator is well aligned with the positioner shaft, and that the two are coupled together with a minimum of
backlash – any backlash acts to deteriorate the performance of the positioner/actuator combination.
It is also essential that the 90 degree travel of the actuator moves the positioner shaft through the correct 90 degree
range of travel. The easiest way to ensure that this happens is to mount the discrete unit with the lid and indicator in place –
set both the actuator and positioner to mid travel, and mate the two in this orientation. Don't take any chances with this, since
misorientation of the positioner shaft and consequent movement beyond its designed range of travel will probably result in
damage to the positioner pot drive mechanism. With moulded coupling versions, the Namur drive or Kinetrol square option is
an insert in the coupling which can be removed by releasing the central screw.
2.1 Mounting of Direct Mounting Units onto Kinetrol Positioner-Type Actuators
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Title : Installation, Operation & Maintenance Instructions – Digital EL Positioner
NOTE: External electrical connector terminals are also identified on a label inside the lid.
When the lid is removed for connection/adjustment, do not wipe grease from cover shaft seal.
2.3.1 Air supply.
Connect air supply (pressure between 3.5 and 7 bar, 50 and 100psi.) to the supply port. It is essential that the air is clean, dry
and oil-free. Quality class 6.4.4 (according to ISO standard 8573.2001) is easily adequate – this implies 5 micron max.
particle size, 3 deg. C dew point max., and 5 mg/cubic metre max. oil content.
2.3.2 DIN Plug Option.
DIN plug models without the optional limit switches are supplied with only one 4-way DIN plug on the positioner box, and a
removable permanent sealing plug covering the second conduit entry, where another DIN plug can be fitted if it subsequently
becomes necessary. If a DIN plug model does have the limit switch option, then a second 4 – way DIN plug is fitted; because
each limit switch is a 3 terminal device, and there are only two terminals available on the DIN plug for each of the two
switches, it is necessary to select normally-open or normally closed function for each switch by connecting the internal wires
from DIN terminals A and B to the appropriate terminal inside the box (see Figure 4 above) – the units are supplied connected
for normally-open function. If proximity sensors are fitted, then this problem does not arise.
2.3.3 Positioner Signal.
The positioner signal must be 4-20mA. The positioner gives a positioning response between 0 and 90 degrees linearly or non-
linearly related to the signal. The positioner is loop powered – that is the signal itself supplies all the electrical power, and no
separate power source is needed. In order to supply enough power, the unit needs between approximately 6 and 8 volts to
drive the signal current through it – it behaves electrically like a resistor in series with a zener diode. A typical 4-20mA source
with a 24v DC supply is compatible with this input, and can drive a maximum of 2 units in series on one loop.
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2.3 Air and Electrical Connections.

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Title : Installation, Operation & Maintenance Instructions – Digital EL Positioner
2.3.4 Angle Retransmit Supply.
The optional angle retransmit circuit is also loop powered, requiring 14 to 30 volts DC to drive the 4-20mA current through it –
the current passed is linearly proportional to the actual positioner shaft angle. The retransmit circuit reads the same angle
transducing potentiometer as the positioner circuit – however, the angle retransmit circuit remains functional on loss of
positioning signal and/or air supply, and the positioner remains functional as long as the signal is present, even if the angle
retransmit circuit is fitted and there is no supply to energise its loop. Nevertheless, the angle retransmit circuit is electrically
isolated from the positioner signal circuit.
3. SCHEMATIC FUNCTIONAL DIAGRAM.
4. SET UP.
4.0 Introduction
When the positioner/actuator combination is installed in its application, set up the control adjustments if necessary. For most
applications, it is likely that the factory settings will be satisfactory – the low and high current points are set to give 0-90 degree
movement in response to a 4-20mA signal, the flow regulators are set for maximum travel speed, and the proportional gain
and damping settings adjusted for a good level of sensitivity and smoothness suitable for most applications. The jumper is set
in the “off” position to give linear characteristics with travel extrapolated beyond the low and high current settings. If you need
to change the settings, read the following section carefully.
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Title : Installation, Operation & Maintenance Instructions – Digital EL Positioner
4. SETUP (continued).
4.1 Setting Travel Speed.
Set the travel speed using the exhaust flow adjuster screws (see Figure 4.). This
only applies if you want to reduce the speed from its supplied maximum factory
setting.
4.2 Setting Optional Limit Switch Cams.
Optional limit switch cams are factory set to give end-of-travel switching with one
switch each end. The switching can be set to occur anywhere in the travel range
for each switch, by relaxing the cam clamp screw and rotating the cam to
position. Set the lower cam first. Take care to avoid the clamp section of a cam
striking a switch at any point in the actuator's travel. Two possible types of
coupling require slightly different approaches to setting:
4.2.1 Moulded coupling cams, shown in figure 6a, can be adjusted using light pressure to rotate in 1 degree increments. Adjust
the lower cam first using a screwdriver to lever against special pegs moulded into the carrier plate or use finger pressure.
Secondly move the upper cam using finger pressure only. Graduated marks on the top of the coupling are provided to gauge the
position of the actuator with the lid removed. This can be lined up with an arrow marked on the servo valve lid.
4.2.2 Metal coupling cams are adjusted by releasing the screw shown in figure 6b, moving to desired position and re tightening.
Set the lever cam first. Ensure the clamp section of the cam does not strike a switch at any part in the actuator's travel.
4.3 Overview – Electronic Settings.
The EL digital positioner circuit can operate to give actuator position accurately proportional to input current, or it can operate as
a non-linear device accurately following one of a number of fast open, or slow open, exponential curves. Linear or non-linear, it
can easily be calibrated to scale its operating line, or curve, between any two user defined points in its operating range. The
positioner circuit is powered entirely from the 4-20mA input signal. It is tuned and calibrated by simple and quick operation of its
three push buttons, with red LED (light emitting diode) indication of the selected parameter. The positioner can also calibrate
itself automatically to the actuator or valve endstops. The actuator dynamic response can be optimised by simple adjustment of
the positioner circuit proportional gain and damping variables. All tuning and calibration data is stored digitally, and is retained in
non-volatile memory, so that the positioner powers up with all the same settings it had when last powered down.
The positioner may be operated either as a linear or non-linear device. Non-linear operation is enabled by fitting a jumper link to
the positioner with the positioner (and position retransmit if fitted) powered down (i.e. input current at 0 mA). When the positioner
is powered up with the link “on” (see figure 6 for its position), it will then operate as a non-linear device for as long as it remains
powered up. Conversely, when the positioner is powered up with the link “off”, it will operate as a linear device as long as it
remains powered up. Changing the link from “on” to “off” or vice-versa while the circuit remains powered up will not cause a
change from non-linear to linear operation – the position of the link is only effective during power up.
Whether operating as a linear or non-linear device, the positioner has two distinct modes of operation, Normal Mode and Setup
Mode.
In Normal Mode the positioner simply positions its actuator in response to the 4-20mA input signal. When the positioner is
powered up, it always starts in Normal Mode. In Normal Mode, the LEDS are not lit. The positioner stays in Normal Mode until
Setup Mode is selected manually.
In Setup Mode the positioner can be tuned and calibrated for its application. Although the position is still controlled, it does not
always follow the input signal. When tuning and calibration is complete the positioner should always be returned to Normal Mode
for continued normal use.
Operating in Setup Mode is described in the following sections.
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Title : Installation, Operation & Maintenance Instructions – Digital EL Positioner
4. SETUP (continued).
4.4 Default Settings and Reset Procedure.
The positioner can be reset with a complete set of default values when powered up in any operating mode, by pressing all three
push buttons (UP, DOWN and SET) simultaneously. This will overwrite all the existing proportional gain, damping, curve
selection and calibration data with default values which are suitable for a typical forward acting linear positioner with mid range
values for proportional gain and damping (but not necessarily optimised for a particular application). This procedure is useful in
the case where errors in calibration have resulted in positioner behaviour which seems incomprehensible, and it is necessary to
return to a predictable basic setup. The positioner should always be tuned and then recalibrated immediately after this resetting
process.
4.5 Entering and Leaving Setup Mode.
Setup Mode is selected from Normal Mode by simultaneously pressing the UP and the SET push buttons (i.e. the two outside
ones). This causes the LED labelled PGAIN (short for Proportional Gain) to light continuously. In Setup Mode, each of the
parameters in the list below may be selected for adjustment by pressing the UP or DOWN push buttons as required. The
parameter selected is indicated on the positioner circuit by an LED lighting next to the parameter's name.
PGAIN - Proportional Gain
DAMP - Damping
CURVE - Non-Linear Curve Selection
LOW - Low Current Point Calibration
HIGH - High Current Point Calibration
POT - Feedback Potentiometer Bottom of Range Setting
When the required parameter has been selected for adjustment, the SET push button is pressed to allow adjustments to be
made – the LED next to the selected parameter starts to blink, to indicate that Adjust Mode is active. Operation in the Adjust
Mode for each parameter is described in the following sub-sections. To leave Adjust Mode, press the SET push button again –
this causes the LED to light continuously, and allows movement between parameters again.
Note: There is no Adjust Mode for the feedback potentiometer bottom of range setting, but the automatic end stop finding
sequence can be initiated when this parameter is selected.
To leave set up mode (when the adjustments have been made and the SET push button pressed to leave Adjust Mode), press
the DOWN push button repeatedly to move down the parameter's and off the end of the list – at this point the LEDs cease to
light, and the positioner is back in Normal Mode.
4.6 Automatic Endstop Finding Procedure.
The positioner can automatically calibrate itself to range between any mechanical end stops (either the built-in actuator stops,
or any external stops built into the application). During the finding sequence, the positioner moves the actuator up to the top
and bottom stops and records their positions. It then uses these positions as the HIGH and LOW positions in the calibration
data, and applies the existing values for HIGH and LOW current input. Note that if the positioner was reverse acting before the
sequence, it remains so after the sequence.
The End Stop Finding Sequence starts when the POT parameter is selected, and the UP and SET push buttons (i.e. the two
outside push buttons) are pressed simultaneously. The POT LED starts to blink, and the actuator moves steadily up scale from
its set position. When its movement is stopped by the the top physical end stop, the positioner waits briefly, then moves the
actuator steadily downscale until it runs against the bottom physical endstop, where again it waits briefly, and finally moves
quickly back to the set position. The calibration data is written to non-volatile memory while the actuator pauses at its bottom
stop.
If the positioner is in service on an application where excursions to the end stops will be disruptive, avoid initiating this
sequence.
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Title : Installation, Operation & Maintenance Instructions – Digital EL Positioner
4. SETUP (continued).
4.7 Proportional Gain and Damping Settings (for Smoothness and Sensitivity).
Select Setup Mode, and the first parameter selected is automatically PGAIN – Proportional Gain. Press the SET push button,
and the PGAIN LED will start blinking. The value of the parameter can now be increased or decreased by pressing the UP or
DOWN push buttons as required. There are twenty nine (29) PGAIN settings which can be selected, the setting altering by a
factor of about 1.1 each time the UP or DOWN button is pressed. The default setting lies in the middle of the range, giving
fourteen settings above and fourteen below. Any button presses beyond the last (fourteenth) will have no effect.
Note: As soon as the UP or DOWN push button is pressed, the new PGAIN value is stored in non-volatile memory and is
retained even if the positioner is de-energised before leaving Adjust and Setup Modes.
The positioner is active while adjusting the PGAIN setting, and continues to follow the input signal. This gives the opportunity to
change the input signal in a manner typical of the application, and to observe qualitatively the response of the positioner, and
how it has been affected by changing the PGAIN setting, so as to optimise the response. Pressing the UP button maximises
the sensitivity and accuracy, at the cost of increased jerkiness of response when the signal is ramped smoothly, and if you go
too far this increases the proportional gain so much that the positioner becomes unstable and hunts around the position set by
the signal. Pressing the DOWN button maximises smoothness during ramping of the signal, at the cost of losing rapidity of
response to small changes in signal. When the right setting has been found, press the SET button again to leave Adjust Mode
– the PGAIN LED will now light continuously.
The DAMP (damping) parameter should be set after the PGAIN has been optimised. In Setup Mode select the DAMP
parameter (second up from PGAIN) by pressing the UP button until the DAMP LED lights continuously. Press the SET button to
select Adjust Mode, and the DAMP LED will blink. Damping can be increased and decreased by pressing the UP or DOWN
buttons. There are twenty nine damping settings which can be selected, the setting altering by a factor of 1.1 each time the UP
or DOWN pushbutton is pressed. The default setting lies in the middle of the range, giving fourteen settings above and fourteen
below. Any button presses beyond the last (fourteenth) setting will have no effect.
Note: As soon as the UP or DOWN button is pressed, the new DAMP value is stored in non-volatile memory, and is retained
even if the positioner is de-energised before leaving Adjust and Setup Modes.
The positioner is active while adjusting the DAMP setting, and continues to follow the input signal. This allows the signal to be
waggled to optimise the response while still adjusting the DAMP setting. Try stepping the signal suddenly so that the positioner
approaches setpoint at full speed having travelled 45 degrees or more, and adjust the DAMP setting to just avoid overshoot
here. Try this travelling up and downscale. When the right setting has been found, press the SET button again to leave Adjust
Mode – the DAMP LED will now light continuously.
4.8 Low Current Point and High Current Point Settings. (Replaces Zero and Span Adjustment).
The positioner characteristic can be accurately calibrated by setting two points, the Low Current Point (LCP) and the High
Current Point (HCP). Each point is defined by a position and an input current. These points can lie anywhere in the range of
travel of the actuator, and in the input signal range of 4 to 20 mA. The only other restriction is that the input current at the HCP
must exceed the input current at the LCP by at least 5mA. To obtain the best accuracy, it is necessary to select the two points
as far apart as possible. In both linear and non-linear operation this allows forward acting, reverse acting, and forward or
reverse acting split range characteristics to be implemented. Table 1 below shows some illustrative examples.
Figure 7. Illustration of LCP and HCP
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Title : Installation, Operation & Maintenance Instructions – Digital EL Positioner
4. SETUP (continued).
4.8 Low Current Point and High Current Point Settings. (continued).
Table 1. Various Sets of LCP and HCP Settings Table
To set LCP, select the LOW parameter in Setup Mode by pressing the UP button until the LOW LED lights continuously. Press
the SET button to select Adjust Mode, and the LOW LED will blink. Adjust the input signal current within the range 4-20mA to the
value you want to define for the Low Current Point – note that changes in input current within the 4-20mA band do not result in
positioner movement at this stage – the positioner holds the actuator at the angle where it was before Adjust Mode was
selected, irrespective of input current. Press the UP or DOWN buttons to move the positioner to the angle you want to define for
the Low Current Point – if you hold the button down continuously, the positioner will traverse the actuator steadily, or if you give
short blips it will move approximately 1/40 degree (one fortieth) for each blip, to allow precise edging into exactly the required
position. When the actuator is in exactly the position you want, and the signal is adjusted to exactly the value you want (this can
be readjusted after the position has been set if you want), press the SET button again to record the signal and position as the
Low Current Point, whereupon the actuator will make a small leap and then settle back to the LCP again, the positioner will
return to Setup Mode, and the LOW LED will light continuously. The positioner will now respond to its input signal again.
Note: As soon as the SET button is pressed, the LCP position and signal are stored in non-volatile memory, and are retained
even if the positioner is de-energised before leaving Setup Mode.
To set HCP, select the HIGH parameter in Setup Mode by pressing the UP button until the HIGH LED lights continuously. Press
the SET button to select Adjust Mode, and the HIGH LED will blink. Adjust the input signal current within the range 4-20mA to
the value you want to define for the High Current Point – note that changes in input current within the 4-20mA band do not result
in positioner movement at this stage – the positioner holds the actuator at the angle where it was before Adjust Mode was
selected, irrespective of input current. Press the UP or DOWN buttons to move the positioner to the angle you want to define for
the High Current Point – if you hold the button down continuously, the positioner will traverse the actuator steadily, or if you give
short blips it will move approximately 1/40 degree (one fortieth) for each blip, to allow precise edging into exactly the required
position. When the actuator is in exactly the position you want, and the signal is adjusted to exactly the value you want (this can
be readjusted after the position has been set if you want), press the SET button again to record the signal and position as the
High Current Point, whereupon the actuator will make a small leap and then settle back to the HCP again, the positioner will
return to Setup Mode, and the HIGH LED will light continuously. The positioner will now respond to its input signal again.
Note: As soon as the SET button is pressed, the HCP position and signal are stored in non-volatile memory, and are retained
even if the positioner is de-energised before leaving Setup Mode.
4.9 Reversing Clockwise/ Anticlockwise Sense of the Positioner.
The LCP and HCP settings described in the previous section can be used with complete success to reverse the sense of the
positioner, using settings such as the reverse settings listed in Table 1. However, this will not change the direction of movement
on loss of signal – see the next section for how to set this as desired.
Low Current Point High Current Point Description
Input
Angle
Input
Angle
Current, mA
Degrees
Current, mA
Degrees
4 0 20 90 Forward Acting, 100% range
4 90 20 0 Reverse Acting, 100% range
4 0 12 90 Split Range Forward Acting, 50% bottom range
4 90 12 0 Split Range Reverse Acting, 50% bottom range
12 0 20 90 Split Range Forward Acting, 50% top range
12 90 20 0 Split Range Reverse Acting, 50% top range
4 0 20 45 Forward Acting, 200% range
4 45 20 0 Reverse Acting, 200% range
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Title : Installation, Operation & Maintenance Instructions – Digital EL Positioner
4. SETUP (continued).
4.10 Changing the Direction of Movement on Loss of Signal.
On being de-energised with air supply still fully pressurised (i.e. on disconnection of the signal, or when the signal falls below
3.5mA), the positioner moves the actuator in a direction set by the de-energised position of the servo valve. This direction of
movement is independent of the LCP and HCP settings described in the sections above.
Movement on loss of air pressure is unpredictable for double acting positioners – if position needs to be held on loss of
pressure, then it is necessary to order an external pressure sensing lockout valve assembly, and if a definite end of travel
position is required on loss of pressure, then it is necessary to order a spring return unit.
On double acting actuators the unit is factory set to move clockwise (as viewed from the positioner lid) on loss of signal.
On spring return actuators the unit is factory set to move in the spring return direction on loss of air, or on loss of both air and
signal, but it is set to move clockwise (as viewed from the positioner lid) irrespective of spring direction on loss of signal only.
To change the direction of movement on loss of signal, carry out the following steps:
(1) Disconnect air supply and signal.
(2) Undo screw holding down changeover block (see Figure 6).
(3) Rotate changeover block 90 degrees, taking care to keep rubber gasket lined up with holes in body.
(4) Re-tighten screw holding down changeover block making sure it remains in alignment with the body.
(5) Undo outer two angle pot wire terminal screws, swap blue and yellow wires over to reverse sense of pot
connection, and re-tighten screws.
(6) Re-connect air supply and signal, and carry out Resetting Feedback Pot procedure (see next section).
4.11 Resetting the Feedback Pot.
This procedure is necessary only if the pot has been moved from its factory setting, or if the direction of movement on loss of
signal has been changed as instructed in the previous section.
The positioner circuit needs the feedback pot to be positioned at the correct angle, such that its wiper reads the right voltage
when the actuator is against its downscale endstop – i.e. against the endstop it reaches when the air supply is connected, but
the signal is disconnected. The circuit itself can identify this voltage when it is powered up in Setup Mode with the POT
parameter selected – when the pot is adjusted correctly, the POT LED changes from lighting continuously to blinking.
To set the pot, first move the actuator to the downscale endstop by connecting the air supply and disconnecting the signal.
When it is in this position, hold it there by fitting a keeper plate if the unit has a spring return set to fail against the opposite stop,
or by simply disconnecting the air supply if the unit is double acting or has a spring return set to fail against this stop. Re-
connect the signal, and set to any current between 4 and 20mA. Select Setup Mode, and press the UP button until the POT
LED lights continuously. Unclamp the pot clamp screws, taking care not to unscrew them too far such that they disengage from
the nuts in the carrier plate. Rotate the pot until the POT LED changes from continuous to blinking illumination. Re-tighten the
clamp screws, and reconnect the air supply. If the unit needed a keeper plate, drive it downscale by disconnecting the signal,
and then remove the keeper plate with the air supply on.
4.12 EEPROM Checksum error
Each time calibration or setting data is written to EEPROM (non-volatile memory) by the positioner circuit, a checksum of all
EEPROM data is calculated and written to EEPROM. Hence if there is a power supply (i.e. signal) interruption during the
EEPROM write procedure, the checksum will not be written correctly, or at all. After the interruption, during its initialisation
routines the positioner carries out a checksum calculation of the data stored in EEPROM. If the newly calculated checksum and
the stored checksum are not identical, the positioner enters an error routine, and does not start Normal Mode operation. This
condition is indicated by the LEDs lighting one after the other in sequence. If this condition is achieved, carry out the reset
procedure described in section 4.3, and then recalibrate as detailed in sections 4.5 to 4.8.
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Title : Installation, Operation & Maintenance Instructions – Digital EL Positioner
4. SETUP (continued).
4.13 Selecting and Setting Up Non-Linear Curves.
The positioner may be operated either as a linear or non-linear device. Non-linear operation is enabled by fitting a jumper link
to the positioner with the positioner (and position retransmit if fitted) powered down (i.e. input current at 0 mA). When the
positioner is powered up with the link “on” (see figure 6 for its position), it will then operate as a non-linear device for as long as
it remains powered up. Conversely, when the positioner is powered up with the link “off”, it will operate as a linear device as
long as it remains powered up. Changing the link from “on” to “off” or vice-versa while the circuit remains powered up will not
cause a change from non-linear to linear operation – the position of the link is only effective during power up.
When the positioner is powered up with the jumper link “on” and the air supply connected, then any one of eleven
characteristic curves may be selected. Press the SET button to go into Setup Mode, and select the CURVE variable by
pressing the UP button until the CURVE LED lights continuously. It is easiest to select the required curve from the eleven
available by setting the input signal current to midway between the LCP and HCP signal current values – for instance, if the
LCP is 4 mA and the HCP is 20 mA, then set the input current to 12 mA for this purpose.
Figure 8. Plots of the Eleven Non-Linear Curves
With the signal set at midway between LCP and HCP values, select Adjust Mode by pressing the SET button, and the CURVE
LED will now blink. The default curve is in fact the linear curve midway between the other non-linear curves (see Figure 8). To
select one of the other curves, press the UP or the DOWN button, and observe the movement of the positioner as its position
conforms to the intersection of the mid value signal with the different curves selected from those defined in Figure 8. Each
button press steps from one curve to the next one, until at the last curve further button presses have no effect. When the
desired curve has been selected, press the SET button to return to Setup Mode.
Note: As soon as the UP or DOWN button has been pressed to select a particular curve, the new curve selection is stored in
non-volatile memory and is retained even if the positioner is de-energised before leaving Adjust and Setup Modes.
Each curve is scaled between the two calibration points LCP and HCP. If input currents are reduced below LCP current or
increased above HCP current, the positioner stops dead at the LCP or HCP position respectively. This is in fact the difference
between the linear curve selected as the default “non-linear” curve, and the linear curve selected when the positioner is
powered up with the jumper “off” - the latter gives positions extrapolated on the the same linear characteristic beyond the LCP
and HCP signals, whereas the former stops dead at the LCP and HCP positions.
F - AR 4587
UPUP
DOWNDOWN
00
1010
2020
3030
4040
5050
6060
7070
8080
90
4400 88 1212 2020 mAmA1616
11
-3-3
-4 -5
Default
22
-2-2
-1-1
33
44
55
Plots of the Eleven Non-Linear CurvesPlots of the Eleven Non-Linear Curves
00
º