wilkerson_dis876
FIGURE 1 DIS Case and Panel Dimensions
DIS876 & 976
POTENTIOMETER INPUT
PROCESS INDICATORS
DESCRIPTION
INSTALLATION
The DIS876 (3½ digit) and DIS976 (4½ digit)
Digital Indicating Systems provide a red or
green LED display, optional isolated DC output voltage or current proportional to the slide
position of a potentiometer and optional single
or dual alarm setpoints. The units include
filtering and conditioning to reduce susceptibility to transients and noisy operations.
The digital display utilizes an auto-zero dualslope integrating A/D converter for accuracy and stability.
DIS Series instruments are designed to be
mounted from the front of a panel through a
standard horizontal 1/8 DIN cutout. Two
mounting cams secure the DIS to the front
panel. Figure 1 shows the case and panel
cutout dimensions.
All DIS instruments are gasketed and, when
properly installed, are NEMA-4X waterproof
and corrosion resistant. Controls are accessible by removing a gasketed front access
panel. The display’s controls are wide ranging so that it can be calibrated to display
engineering units. Decimal point selection is
made with a switch, also accessible from the
front. A complete set of engineering unit
labels is sent with each DIS. Once the display
has been adjusted to read the correct engineering units, the alarm setpoints can be
adjusted without test equipment and without
disturbing the output voltage or current.
To install the DIS in the cutout, turn the two
cam-lock screws (on the front panel - see
Figure 1) counterclockwise until the cams
move far enough toward the rear to clear the
panel thickness. Insert the case through the
panel cutout and turn the cam-lock screws
clockwise until both are tight.
GROUNDING
All DIS models should be properly grounded
for safety and for minimum noise pickup.
Connect the GROUND lug on the instrument's
rear panel to earth ground.
CONTROLS
CALIBRATION
All user-adjustable controls are located behind the front panel. To gain access, simply
loosen the two screws and remove the
gasketed CALIBRATION CONTROLS panel.
Front-panel controls include:
All DIS Series instruments are precisely calibrated at the factory. In normal use only the
alarm setpoint and deadband, and possibly
the display range, need to be adjusted. However, complete user recalibration is possible.
If you need to recalibrate, proceed as follows:
Display: zero, span and decimal point.
Alarm setpoint calibration switch.
Alarms (optional): setpoint and deadband.
Transmitter output (optional): zero and span.
Each optional alarm board also contains a
zero and span control. These are not normally adjusted by the user, and require
removal of the instrument assembly from its
housing.
Input Connection
Connect a precision DC voltage or current
source to the INPUT + and - terminals. For low
level inputs, an input cable shield may be
connected to the SH terminal.
FIGURE 2 - Calibration Control Locations
Each setpoint has an LED to indicate alarm
status. The alarms have adjustable deadbands. Terminations are made to a screw
terminal connector on the rear of the case.
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2
DISPLAY CALIBRATION
(4½ Digit Only) Set the display OFFSET
jumper to the proper position, as shown in
Figure 3.
To calibrate the display, rotate the DECIMAL
POINT select switch until the desired decimal
point illuminates. Set the input source for the
low end value and adjust the display zero
(DISPLAY Z) control for the desired reading
on the display. Advance the input source to
the full scale value and adjust the display
span (DISPLAY S) control for the desired
reading. For maximum accuracy, repeat the
procedure once or twice as the controls
may interact slightly.
Figure 3. Display Zero Offset Jumper
(4½ Digit Only).
Alarm
Setpoint and Deadband
Calibration
The SP CAL switch is a three-position toggle
which allows the instrument to display each
alarm’s setpoint. No test equipment is required to set the alarms with a properly
calibrated display. To set the alarm #1 setpoint,
put the toggle in the up (1) position and adjust
the AL1 SP control until the display indicates
the desired setpoint. Put the toggle down (2)
to similarly adjust AL2 SP. Returning the
toggle to its center position provides normal
operation.
Turn each alarm deadband (DB) control fully
counterclockwise for minimum deadband
(about 0.25%) or fully clockwise (25 turns)
for maximum deadband (about 100%). The
deadband is approximately symmetrical about
the setpoint. If precise deadband settings are
needed, connect a calibration source to the
input as described earlier. Vary the input up
and down and adjust the DB controls until the
desired amount of deadband is achieved.
Alarm Zero and Span
The alarm zero and span adjustments calibrate the alarm circuitry so that the display
properly indicates the setpoint. These adjustments are factory set and do not normally
need to be changed unless the instrument
has been repaired. If you need to recalibrate,
remove the instrument from its housing (refer
to the “Adding Options” section) and connect
power and a calibration input. Turn each
alarm’s deadband (DB) control fully counterclockwise for minimum deadband.
The zero and span controls are located on the
top edge of each board. ZERO is nearest the
front, SPAN nearest the back.
Each alarm has an LED to the left of the digits
that lights when the alarm trips and goes out
when the alarm resets. Alarm #1 is the upper
LED and alarm #2 is the lower LED.
With the SP CAL switch in its center position,
set the input to the low end value and observe
the reading on the display. Put the switch in
the up position for alarm #1 or down for alarm
#2 and adjust the alarm’s setpoint (SP) until
the DIS again displays the low end value.
Adjust the alarm’s ZERO control until its LED
lights.
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Return the SP CAL switch to its center position, increase the input to full scale and
observe the display reading. Put the switch
back in the up (alarm #1) or down (alarm #2)
position and adjust the alarm’s SP for full scale
display. Adjust the alarm’s SPAN control until
its LED lights.
Repeat these adjustments once or twice, as
the controls may interact slightly, then return
the SP CAL switch to its center position. Set
the alarm setpoints and deadbands as described above.
Transmitter Output Calibration
Set the input to the low end value and adjust
the transmitter zero (TRANSMITTER Z) control for the desired output. Increase the input
to the full scale value and adjust the transmitter span (TRANSMITTER S) control for the
desired value. For maximum accuracy, repeat the procedure once or twice as the
controls may interact slightly.
RELAY CONTACT PROTECTION
When inductive loads such as motors, relays
or transformers are switched, voltage transients may be generated which exceed the
ratings of the relay contacts. The resulting
arcing can quickly destroy the contacts.
(Refer to the SPECIFICATIONS below for the
relay contact ratings.)Surge suppression is
required across inductive loads to guard
against premature relay failure. Figure 4 illustrates diode surge suppression for a DC load.
The diode’s operating (peak inverse) voltage
should exceed the load’s supply voltage by at
least 50% and should have a current rating of
at least one ampere.
Figure 5 shows surge suppression for an AC
load, using an MOV (Metal Oxide Varistor)
and a capacitor. The breakdown voltage
ratings of both the MOV and the capacitor
must exceed the peak AC voltage.
With normal sine-wave power, PEAK = 1.414
x RMS voltage. For 115V AC power a 200 volt
peak rating is recommended.
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SPECIFICATIONS
INPUT POTENTIOMETER
RESISTANCE
any value from 100 ohms
to 100 kilohms
INPUT SPAN ADJUSTMENT
70% to 100% of pot rotation
INPUT OFFSET ADJUSTMENT
0 to 25% of pot rotation
INPUT IMPEDANCE
>10 megohms
EXCITATION
1 V, 10 mA max load
OUTPUT RANGE
Voltage
select any range between ± 10 V,
10 mA max load (min span 0.2 V)
Current
select any range from 0 to 20 mA max,
24 V compliance* (min span 1 mA)
SETPOINT
each alarm 0 to 100% of span
DEADBAND
0.25% to 100% of span
ACCURACY
±0.1% of span
WARRANTY
DISPLAY (876)
Digit Size
.56" LED, 3½ digits, ±1999
Decimal Point
±1.9.9.9
Digit Size
.56" LED, 4½ digits, ±19999
R
Control Range Zero
±19999
Span
min span 100/max span 20000
DISPLAY
Update
3/sec
RELAY CONTACTS
(SPDT)
Inductive Load:
1
/8HP max at 120/240 VAC
OUTPUT RIPPLE
OPERATING TEMPERATURE
(peak-to-peak)
<0.1% of span
TEMPERATURE STABILITY
ISOLATION
Output/Input
>500 M ohms
Breakdown Voltage
>600 VAC rms
Relays are not covered by the warranty.
Decimal Point
±1.9.9.9.9
Output
±0.025% of span
120 dB, DC to 60 Hz
In addition to the display, alarm and transmitter
choices described above, the following options are available:
DISPLAY (976)
±1999
Span
min span 10/max span 2000
Display
±0.01% of span
COMMON MODE REJECTION
DIS SERIES OPTIONS
H/L H = High Alarm. Alarm occurs on an
increasing signal.
L = Low Alarm. Alarm occurs on a
decreasing signal.
Specify H or L for single alarms.
(H supplied if not specified.)
Specify H/H, H/L, or L/L for dual
alarms. (H/L supplied if not specified.)
Control Range Zero
Resistive Load:
5A max, 150W max,
240 VAC max,
30 VDC max
LINEARITY
The DIS Series of products carry a limited
warranty of 5 + 5 years. In the event of a
failure due to defective material or
workmanship, during the 5 year period, the
unit will be repaired or replaced at no
charge. For a period of 5 years after the
initial 5 year warranty, the unit will be
repaired, if possible, for a cost of 10% of
the original purchase price.
Reverse Sense. Normal condition for
the relays is energized. They deenergize for alarm conditions or loss
of power to provide fail-safe relay
operation. Option R reverses this
logic
RD Reverse-acting display. The display
reading decreases as the input
increases.
RT Reverse-acting transmitter. The
transmitter output decreases as the
input increases.
U
All circuit boards conformal coated
for protection against moisture.
14°F to 140°F/-10°C to 60°C
±0.02% of span/°CPOWER
115 VAC ±10%,
50 or 60 Hz
230 VAC ±10%,
50 or 60 Hz
(4 W max)
* Compliance: The sum of all voltage
drops in the output loop cannot
exceed 24 V at rated current
(1200 ohms @ 20mA).
5
6
ADDING OPTIONS
DIS Series II alarm and transmitter output
options consist of plug-in circuit cards,
which may be added by the user. To do so
it is necessary to unscrew and remove the
back panel, slide out the internal assembly,
plug in the appropriate cards and calibrate.
It is not necessary to remove the housing
from its installation.
CAUTION: The DIS circuitry is
precise, sensitive and closely
spaced.
Circuit
board
contamination can lead to errors
and instability, especially at high
humidities. Handle all circuit boards
by their edges only, or wear clean
gloves, to avoid contamination.
Begin by disconnecting the wires from the
rear terminals. If you wish to remove the
instrument from its installation, turn the two
cam-lock screws (Fig. 1) counterclockwise
several turns and slide the instrument out of
its mounting.
Unscrew the four screws which hold the
rear panel in place. Remove the panel, and
slide the internal assembly out of the case.
Figure 6 shows the internal assembly. To
install options you must first remove the
display assembly as shown. To remove it pull
straight up.
To install or remove an option card, simply
plug or unplug it from the appropriate position
per Fig. 6. ENSURE ALL CONNECTOR
PINS ARE ENGAGED.]
Reinstall the display assembly. ENSURE ALL
GOLD PINS ARE ENGAGED.
Calibrate the new options as described earlier
under CALIBRATION. It should not be
necessary to recalibrate the display itself, or
any options which were previously installed
and calibrated. The instrument may be
calibrated while out of its case.
(CAUTION: Avoid exposed PC traces
and wires, which may carry hazardous
voltages.)
For best accuracy (and safety), however,
reinstall the instrument in its case and allow
15 minutes warmup before calibrating.
Figure 6 shows the internal assembly. To
install options you must first remove the
display assembly as shown. Pull it straight
up.
FIGURE 6 - ADDING OPTIONS
The display assembly must be unplugged to allow cards to be
installed.
Specifications are subject to change without notice. ©2007 Wilkerson Instrument Co., Inc.
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DWG#W101981B 4/07
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