User guide

DWYER INSTRUMENTS, INC. Phone: [phone] www.dwyer-inst.com
P.O. Box 373 • Michigan City, IN 46361-0373, U.S.A. Fax: [phone] e-mail: [e-mail]
The device is a low cost temperature transmitter designed to
accept a standard platinum resistance sensor (Pt100 2 or 3 wire)
to BS1904 or DIN 43760 and convert the temperature to an
industrial 4-20mA current. It is housed in a DIN standard con-
necting block.
The transmitters are available in 3 standard factory calibrated
ranges. The enclosure provides trim potentiometer access, allow-
ing fine re-calibration adjustments to be made at both ends of the
scale.
Fig 1 shows the method of connection to provide a 4-20 mA cur-
rent loop output. the Pt100 sensor shown would normally take
the form of a probe assembly with a three wire output. The out-
put loop shows a 24V dc power supply, used to provide loop exci-
tation, the transmitter, and a load all connected in series. the load
symbol represents other equipment in the loop, normally indica-
tors, loggers etc. Sometimes these instruments come with the
24V supply built in as standard, this simplifies wiring and reduces
cost. Care must be taken when designing the 4-20mA circuit to
ensure that the total burden of the loop, that is the total voltage
requirements of all the equipment in the loop added together,
does not exceed the power supply voltage. If a number of instru-
ments are connected in the loop, ensure that only one instrument
is tied to ground. Grounding the loop at two points will result in
shorting out part of the loop and therefore any instruments in that
part of the loop will not operate.
Series 651A Temperature Transmitter
Specifications - Installation and Operating Instructions
Bulletin E-33
SPECIFICATION @ 20 deg C, (68 deg F)
Input Pt100 sensor to BS1904 or DIN43760
100 R @ 0 deg C (32 deg F)
FI=38.5 R, 2 or 3 wire.
Output 4-20 mA Loop powered ,
Max 30 mA
Loop Supply 10 to 32 V d.c.
Loop Resistance 700R @ 24 V
Loop Protection Reverse connection protected
Loop Sensitivity 10 uA/volt
Accuracy +/- 0.2 deg C, (0.36 deg F)
plus +/-0.25% of reading
Temp Stability Zero Drift Typ 0.05%/ deg C (0.09 deg F)
Span Typ 0.002%/deg C (0.0036 deg F)
Ambient Temp 0 / 50 deg C (32 / 122 deg F) Operating
-40 / 70 deg C (-40/158 deg F) Storage
Ambient Humidity 0 / 95% (Non Condensing)
Connection Screw Terminal
Cable Size Recommended max wire 2.5mm (0.1˝)sq
.
INSTALLATION
The transmitter is mounted using two 5.5mm , (0.22˝) diameter
holes, on standard 33mm, (1.3˝) centers. this transmitter has been
specifically designed to be mounted inside a DIN standard probe
head enclosure, which should provide adequate protection from
moisture, corrosive atmosphere etc. All cable entries should be
sealed suing the correct size cable gland. Care must be taken
when locating the transmitter to ensure the ambient temperature
will remain inside the specified range of 0 to 50 deg C, (32 to 122
deg F). Figs 2&3 show the mechanical layout and a typical appli-
cation of the transmitter mounted inside a probe head enclosure,
with sensor wires entering through the transmitter body.
Mounting holes : 2 hole 0.22. 1.3 centers
Center-hole sensor wire entry : 0.16 diameter
Bulletin E-33 6/22/05 3:04 PM Page 1