HD 786TR1_HD 788TR1_1

HD 788TR1, HD 788TR1-I, HD 786TR1, HD 988TR1, HD 988TR1-I, HD 988TR2 – 4÷20 mA Configurable Temperature Transmitters for Pt100 Sensors

HD 788TR1, HD 788TR1-I, HD 786TR1, HD 988TR1, HD 988TR1-I and HD 988TR2
are 4÷20 mA configurable transmitters with microprocessor for Pt100 Platinum
temperature sensor. They convert the temperature variations found with any
standard Pt100 sensor (100Ω at 0°C) into a linear current signal with two leads in
the field 4÷20 mA. Linearization with a digital technique allows excellent precision
and stability to be obtained.

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Product Description

are 4÷20 mA configurable transmitters with microprocessor for Pt100 Platinum
temperature sensor. They convert the temperature variations found with any
standard Pt100 sensor (100Ω at 0°C) into a linear current signal with two leads in
the field 4÷20 mA. Linearization with a digital technique allows excellent precision
and stability to be obtained. User can set the 4÷20 mA output (or 20÷4 mA) in
any temperature range within the field -200…+650°C, with a minimum amplitude
of 25°C; it may be simply reprogrammed by pressing a key, without any need to
regulate jumpers, potentiometers, software, etc. A led indicates any alarm situations
(temperature outside the set range, broken or short-circuiting sensor) and assists
the user in the programming phase. The 4÷20mA output of models HD788TR1-I
and HD988TR1-I is galvanically isolated from the Pt100 input. The transmitters
are also protected against inversions of polarity. The HD 788TR1, HD 788TR1-I are
specifically designed for installing in type DIN B connecting heads, while the HD
988TR1, HD988TR1-I and HD 988TR2 are suitable for fitting in containers with a
35 mm DIN bar connection. As well as the 4÷20 mA output, the HD 988TR2 has a

convenient 3 and 1/2 digit display (height 10 mm) which allows the display of the
measured temperature. The HD786TR1 is indicated for wall installation.
Technical data (20°C and 24VDC)
INPUT
HD 788TR1
HD 788TR1-I
HD 786TR1
HD 988TR1
HD 988TR1-I
HD 988TR2
Sensor Pt100 (100Ω at 0°C)
Connection 3 (or 2) wires
Linearization EN 60751, IEC 751
BS 1904 (α=0,00385)
Current into sensor <1 mA
Measuring range -200…+650°C
Default range 0…100°C
Minimum measuring
amplitude 25°C
Influence of the connecting
leads Negligible with coupled lead
Conversion speed 2 measurements per second
Accuracy ±0,1°C ±0,1% of the reading (-100…+500°C)
±0,2°C ±0,2% of the reading (-200…+650°C)
Sensibility to variations of
env. temperature 0,01°C/°C
Working temperature 0…70°C
Storage temperature -40…+80°C
OUTPUT
Output
4…20 mA (or 20…4 mA)
22 mA in case of incorrect programming
or temperature out of range (note 1 and Fig. 2).
Resolution 4 μA
Analogue output: 4 μA
Display: 0,1°C up to 200°C
1°C over 200°C
Power supply voltage 7…30Vdc (protection against inversions of polarity)
Sensibility to variations
of the
feeding voltage Vcc
0,4 μA/V
Load resistance RLMax = Vdc-7
0,022
=> RLMax = 680 Ω @ Vdc = 24 Vdc
Red led It switches on while programming and when the measured
temperature is out of the set range
Input-Output isolation for
models HD 788TR1-I and
HD 988TR1-I
500 Vdc –
Note 1) If the measured temperature T is out of the set range T1…T2 (T1<T2),
HD 788TR1, HD 788TR1-I, HD 988TR1, HD 988TR1-I and HD 988TR2 maintain
4 mA for T<T1 and 20 mA for T>T2 for a dead band of 10°C before going into
error status at 22 mA.
Fig. 2 reports the connection diagrams for the transmitters in the current loop. In
order to obtain the maximum precision, the connection to the Pt100 should be
performed with 3 wires and with wires having the same diameter so to grant the
same impedance in each connection. The symbol RL (load) represents any device in
the current loop that is to say an indicator, a controller, a data logger or a recorder.

Programming
All transmitters are supplied by default with a range 0…100°C, anyway user can set
a different range by using the following accessories:
• continuous 7-30 Vdc power source,
• Pt100 calibrator or set of precision resistors,
• precision ammeter with minimum range 0…25 mA,
And by following this procedure:
1. Connect the transmitter to set-up as shown in Fig. 2 and set the Pt100 calibrator at
the required temperature suitable for 4 mA (for example, assuming that you want
to set the range -50…+200°C, you will set the calibrator to -50°C or equivalently
you will connect a resistance of 80,31Ω between terminals 1 and 3 while 1 and
2 shorted).
2. Wait 10 seconds until the measurement becomes settled, then keep pressed the
programming key for at least 4 seconds, until the LED flashes once and remains
lit. When the key is released the LED flashes.
3. Set the Pt100 calibrator at the required temperature for 20 mA (according to the
above example, set the calibrator at +200°C, or alternatively connect 175.86Ω
resistance between terminals 1 and 3 with 1 and 2 shorted).
4. Wait 10 seconds until the measurement becomes settled, then press the
programming key for at least 4 seconds, until the LED stops flashing. Now release
the key and the LED flashes twice. At this point the SET POINT procedure is
completed.
5. Verify that the setting complies with the required specifications, setting the
calibrator (or connecting the precision resistances) at the values corresponding to
4 and 20 mA and checking the current on the ammeter.

The temperature range programming can be performed by using some precision
resistances of fixed value that simulate a Pt100 sensor value.
For example, the resistance values corresponding to some temperature values are
reported (see Tab. 1).
ORDERING CODES
HD 788TR1: 4÷20 mA/20÷4 mA temperature transmitter for 2 or 3 wires Pt100
sensor configurable in the range -200…+650°C with minimum amplitude
range 25°C, in a container for DIN B 43760 heads.
HD 788TR1-I: 4÷20 mA/20÷4 mA temperature isolated transmitter for 2 or 3
wires Pt100 sensor configurable in the range -200…+650°C with minimum
amplitude range 25°C, in a container for DIN B 43760 heads.
HD 786TR1: 4÷20 mA/20÷4 mA temperature transmitter for 3 wires Pt100 sensor
configurable in the range -200…+650°C with minimum amplitude range 25°C.
Suitable for mounting on wall.
HD 988TR1: 4÷20 mA/20÷4 mA temperature transmitter for 2 or 3 wires Pt100
sensor configurable in the range -200…+650°C with minimum amplitude
range 25°C, in a container for 35 mm DIN bar connection, dimension 1 module.
HD 988TR1-I: 4÷20 mA/20÷4 mA temperature isolated transmitter for 2 or 3 wires
Pt100 sensor configurable in the range -200…+650°C with minimum amplitude
range 25°C, in a container for 35 mm DIN bar connection, dimension 1 module.
HD 988TR2: 4÷20 mA/20÷4 mA temperature transmitter for 2 or 3 wires Pt100
sensor configurable in the range -200…+650°C with minimum amplitude range
25°C, in a container for 35 mm DIN bar connection, dimension 2 modules, with
3½ digit LCD, height 10 mm.
Industrial probes characteristics and dimensions on page TP-10.

 

Download

Manuals and Brochures here.  

HD788TR1_1_2.pdf

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