Flowserve Logix 1200e LGAIM0044 - Manual (Page 35)

Flowserve Corporation, Valtek Control Products, Tel. USA 801 489 8611 44-35
4. Write this number to the Inner Loop Offset.
SoftTools TechCheck Software
1. From the Custom Tuning screen, select the Adjust
ILO button.
2. Allow the position to stabilize.
3. Write the value shown for D/A Average to Inner
Loop Offset.
NOTE: The actuator must not be saturated (D/A out-
put = 0) while setting the Inner Loop Offset.
HART 275 Handheld Communicator
1. Send a 50 percent command using 4-20 mA signal
or digital mode.
2. Proceed to the Status/Technician menu.
3. Locate the D/A Output Voltage.
4. Divide this number by 2.5 V and multiple by 100
percent. Example: D/A Output Voltage = 1.25 V.
Therefore: 1.25 V/2.5 V x 100% = 0.5 x 100% =
50%.
5. Write this percentage value to the Inner Loop Offset.
Digital Filter
This parameter controls a noise reduction filter used
on the readings obtained from command and stem
position sampling. This filter is internal to the posi-
tioner software and is not associated with the external
HART filter. This parameter setting should remain at
0.5.
Spool Valve
The spool valve is a four-way directional valve with
precision features to provide optimal control and low-
air consumption. To help prevent a malfunction of the
spool valve, the positioner supply air must conform to
ISA Standard S7.3 (a dew point at least 18 degrees
below ambient temperature, particle size below 5-
microns, oil content not to exceed one part per mil-
lion). The standard Valtek coalescing filter is highly
recommended to help meet these requirements.
Small particles, oil that has varnished, corrosion, ice,
burrs, and extreme wear could cause the spool valve
to act abnormally. If the spool valve is suspected of
sticking, check it by performing the following proce-
dure:
1. Make sure the valve is bypassed or in a safe
condition.
2. Disconnect the power and air supply to the unit.
3. Remove the spool valve cover by removing the
screw and sliding the cover assembly backwards
until the tab is clear of the slot.
4. Inspect the coalescing filter element in the spool
valve cover for signs of oil, water and debris that
may have come from the air supply. (A clean filter is
white.)
5. Remove the two Phillips-head screws holding the
spool valve to the housing. Inspect the free move-
ment of the spool by carefully sliding the block up
and down on the spool about 0.25 inches (6 mm).
The block should slide on the spool with no resis-
tance. Carefully remove the block from the spool,
ensuring it is removed concentric with the spool.
6. Inspect the block and spool for oil, water, debris
and wear. If oil, water and/or debris are found, the
spool and block can be cleaned with a non-residue
cleaner, lint-free cloth and soft-bristle brush. If wear
is found, replace the driver module assembly or
spool valve. Refer to Spool Valve and/or Driver
Module sections.
7. Before re-assembly, verify the three O-rings are
correctly placed in the counter-bores on the
machined platform where the spool valve block is to
be placed.
8. Carefully slide the block over the spool, using the
machined surface of the housing base as a regis-
ter. Slide the block toward the driver module until
the two retaining holes line up with the threaded
holes in the base. If resistance is still encountered,
re-clean both parts or replace the driver module
assembly or spool valve.
HART Communication
Current Source Interference
HART communication superimposes two frequencies
(1200 Hz and 2200 Hz) on the DC 4-20 mA current
signal. Some current sources (DCS or 4-20 mA cali-
brator) can interfere with the HART signal. This may
prevent communication with ValTalk or SoftTools soft-
ware or the HART 275 handheld communicator. Inter-
mittent communication may also be the result of a
HART incompatible current source. In this case, a filter
is necessary between the current source and Logix
1200 positioner to allow HART communication.
Valtek HART Filter (VHF)
Figure 20 & Figure 21
Flowserve offers a filter (Valtek part no. 10079944)
that must be used on each 4-20 mA line if the current
source interferes with communication. The filter does
not affect the DC current but prevents the source from
affecting the HART frequencies. The filter comes in a
DIN rail mount package.