Flowserve Logix 520MD+ User Instructions Download

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User Instructions - Logix® 520MD+ Series Digital Positioner

FCD LGENIM0105-00

Field Trial Version – Printed October 28, 2011

valve stroke time) in order to determine the gains.  The gains
are  then  set  automatically.    After  a  stroke  calibration,  the
positioner  is  ready  to  control.    See  section    8.4  Stroke
Calibration for more information.
Pressure Sensor Calibration starts an automatic calibration of
the  pressure  sensors.    The  pressure  sensors  are  calibrated
at the factory and typically will not need calibration.  Use this
feature  if  new  pressure  sensors  are  installed.      If  desired,
configure  the  positioner  to  use  the  most  recent  pressure
calibration values after a factory reset.  To do this, write a 1
to  variable  194  using  the  Edit  Variables  page  of  the
ValveSight DTM.
Friction  Calibration  starts  an  automatic  calculation  of  total
system  friction.    This  also  determines  the  spring  rate  and
other values critical to the Pro diagnostic functions.

NOTE: Friction forces may change quickly when a valve

is first placed into service.

Triple  Calibration  performs  Stoke,  Pressure  and  Friction
calibrations in one step.
Command Input Calibration is used to adjust the input range.
The default input range is 4 to 20 mA.

Split Range Example:
A  split  range  is  easily  configured  using  the  Command  Input
Calibration feature.  For example, a 4 to 12 mA signal can be
set  to  correspond  to  a  0  to  100%  stroke.   When  the  display
shows  “Set  0%”,  set  the  command  input  current  to  4  mA.
(The  display  will  show  a  low  Analog  to  Digital  Count  (ADC)
that

corresponds

mA.)

Then

press

the

►

ACCEPT/QUICK-CAL button to set the value. Press the

▼

Down button to move to “Set 100%”. Set the command

input current to 12 mA. (The display will show a high ADC to
correspond to 12 mA.) Again press the

►

ACCEPT/QUICK-

CAL button to set the value. Select the

◄

Back Button to

exit.

Calibration Dates lists the most recent date of each
calibration.

NOTE: To calibrate the Analog Output, see section 14

MULTI-FUNCTION CARD.

10.3.5 Configuration (Positioner Tuning)

The Configuration – Positioner Tuning menu allows the user
to  manually  adjust  individual  tuning  parameters.    All  tuning
parameters  are  automatically  set  to  optimal  values  during
Quick-Cal.    Typically  a  Quick-Cal  is  all  that  is  needed  for
positioner tuning.  See section 8 STARTUP for more details.

CAUTION: Adjusting the tuning parameters will affect

the  responsiveness  of  the  valve  and  could  cause  rapid
changes  to  the  valve  position.  Notify  proper  personnel  that
the  valve  may  stroke,  and  make  sure  the  valve  is  properly
isolated before proceeding.

P-Gain, I-Gain and D-Gain are the proportional, integral, and
differential elements of the feedback algorithm.  These gains

are different for the opening and closing directions because
typically responsiveness is different in each direction.

NOTE: Only those with specific training in PID tuning

algorithms  should  attempt  to  adjust  the  tuning  by  manually
changing the PID values.

Open  Stroke  Time  is  the  fastest  time  it  took  the  valve  to
stroke  from  0%  to  100%  during  Quick-Cal.    Changing  this
parameter  will  affect  the  responsiveness  of  the  valve  in  the
opening direction.

Close  Stroke  Time  is  the  fastest  time  it  took  the  valve  to
stroke  from  100%  to  0%  during  Quick-Cal.    Changing  this
parameter  will  affect  the  responsiveness  of  the  valve  in  the
closing direction.

Minimum  Open  Time  and  Minimum  Close  Time  (Speed
Limits) are used to prevent the valve from moving too quickly.
This can be used when the process is sensitive to rapid flow
or pressure changes.  This shows the time (in seconds) that
the positioner will allow the valve to travel a full stroke.  This
speed limit applies to smaller movements of the valve too.

For  example,  if  the  Minimum  Open  Time  were  set  to  20
seconds, and the command was changed from 40% to 50%,
the positioner would move the valve at a constant rate, taking
2 seconds to complete the move.  If the Minimum Close Time
was set to 0, and the command was changed from 50% back
to  40%,  the  positioner  would  make  the  move  as  quickly  as
possible.

The default values are 0 seconds, meaning the positioner will
move the valve as quickly as possible.

10.3.6 Configuration (Characterization)

The Configuration – Characterization menu allows the user to
change  the  characterization of  the  command.    This allows  a
better match between the input command and the actual fluid
flow  through  the  valve.    This  feature  is  typically  used  with
valves  that  have  non-linear  flow  characteristics.    The
positioner  makes  a  correction  by  applying  an  adjustment  to
the  input  command  according  to  a  characterization  curve.
The  table  below  shows  the  available  characterization  curve
options.    Each  point  of  the  Custom  curve  can  be  adjusted
using the ValveSight DTM.

To  view  the  characterization  curve  options,  set  the
Characterization  switch  “Other”  before  performing  a  Quick-
Cal.  Otherwise,  the  only  option  available  is  “Linear”.      If  a
Quick-Cal  is  not possible, use  the  ValveSight  DTM  to  select
the curve.

Select  the  appropriate  curve  as  required  by  the  process
design.

Custom  -  Select  Custom  for  a  standard  30:1  equal  percent
rangability  curve.    The  curve  may  be  customized  point-by
point.  To modify the Custom curve, use the ValveSight DTM.

CAUTION: Changing the characterization curve may

cause the valve to move suddenly. Notify proper personnel
that the valve may stroke and if required, make sure the
valve is properly isolated before proceeding.

►

Configuration

►

Positioner Tuning

►

P-Gain Open

►

I-Gain Open

►

D-Gain Open

►

P-Gain Close