MODEL 885
TRANSDUCER
INSTALLATION
The Model 885 Pressure Transducer is a 2-wire,
4-20mA, compact instrument with an LCD
Display. It is used for measuring and controlling
the many different media that are compatible
with our sensing element. Positive, negative, and
differential pressures can be measured in ranges
from 0-1” WC to 0-15 PSI with a 4-20mA
output. Split ranges are also available.
INSTALLATION
1. Location- The model 885 pressure transducer
should be placed in as clean, dry and vibration
free a location as possible.
2. Pressure Connections- The 885 pressure
transducer uses 2 barbed fittings for use with
1/8” ID vinyl or rubber tubing. Attach tubing
from positive pressure or higher pressure source
to port marked High (P1) and lower or negative
pressure to opposite port (P2). Arrange tubing to
minimize stress on connections. If possible,
mount with ports facing down to aid in moisture
drainage.
Note: When removing tubing care should be
used to avoid breaking the ports. In some cases
the tubing should be cut off, rather than pulled
off, especially if stiff tubing is being used.
3. Mounting- Attach the Model 885 Transducer
to the mounting surface using 2 fasteners inserted
through the two mounting holes located on either
the side mounting flanges, or the holes at the top
of the case. Do not over-tighten.
ELECTRICAL CONNECTIONS
All electrical connections to the 885 series
transducer are made to the pluggable screw
terminal block. The block is coded as follows.
1)”+” = Supply Positive,
2) “ - “ = Supply (or Controller) Negative.
An external power supply (Vs) delivering
14 - 36 VDC with a minimum of 30mA output
is required to drive the unit. The load must meet
the following requirements:
Minimum Loop Resistance (RLmin):
If Vs<30Vdc, RLmin= 0 ohms
If Vs>30Vdc, RLmin=(Vs-30) x 40 ohms
Maximum Loop Resistance (RLmax):
RLmax=(Vs-14) x 50 ohms
(Example: If Vs=24Vdc, RLmax=500 ohms)
Alternatively, if RL is known:
Vs,min = RL/(50) + 14Vdc
Vs,max = RL/(40) + 30Vdc
Do not exceed
specified supply voltage.
TYPICAL 2 WIRE CONNECTION
•
+ Power Supply
•
- Power Supply
•
- Ctrl Negative
•
Ctrl Ground
CONVERTING 4-20MA TO 1-5 VDC
885 Series Pressure transducers with a 4-20mA
current output can be easily adapted to
controllers requiring 1-5 VDC input. Insert a 250
ohm resistor between the “+” and “-” controller
input terminals. This will safely convert the 4-
20mA signal to 1-5VDC.
OFFSET
The offset of the 885 series transducer is factory
set. If it should need adjustment upon arrival, the
offset pot is located next to the ports on the end
of the unit. With the transducer installed and no
pressure applied place a meter in series with the
negative “-“ and the ground. Turn offset
adjusting pot to desired reading.
CUSTOMER SERVICE
If any problems are encountered during
installation please call the number below for
assistance.
Call 1-800-735-8998
7638 Washington Ave S
Eden Prairie, MN 55344
+1.800.735.8998 • +1.952.942.8743
FAX +1.952.942.8753
www.controllersensors.com
IN-885 Rev A
(1 stránky)
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