HD778TR1, HD978TR1, HD978TR2, HD778-TCAL_1
HD778TR1, HD978TR1, HD978TR2, HD778-TCAL_2

HD778TR1, HD978TR1, HD978TR2, HD778-TCAL- Configurable Temperature Transmitters

HD778TR1, HD978TR1, HD978TR2, HD778-TCAL 4÷20mA – Configurable Temperature Transmitters for K-J-T-N Type Thermocouple. Thermocouple Generator Managed by PC Through RS232C HD778-TCAL

HD 778TR1, HD 978TR1 and HD 978TR2 are 4…20mA two-wired configurable
passive transmitters with microprocessor for K, J, T and N type thermocouple
sensors. They convert the voltage value generated by the thermocouple into a linear
current signal included in the range 4…20mA. The use of digital devices allows
obtaining an excellent precision and stability in time. User can set the 4…20mA (or
20…4mA) output into any temperature range in the measuring range included in the
measuring range of the single thermocouple with a minimum range of 50°C. The
range and type of thermocouple are set by simply using one button. A led indicates
the alarm situation (broken or not connected sensor) and it helps user during the
programming. Moreover, transmitters are protected against polarity inversions.
HD778TR1 is specifically designed to be installed in DIN B type connection heads,
HD978TR1 and HD978TR2 are suitable for mounting on 35 mm DIN bars. Beyond
4…20mA output, HD978TR2 has a 3½ digit (Height 10 mm) display which allows
displaying the measured temperature.

 

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Product Description

HD 778TR1, HD 978TR1 and HD 978TR2 are 4…20mA two-wired configurable
passive transmitters with microprocessor for K, J, T and N type thermocouple
sensors. They convert the voltage value generated by the thermocouple into a linear
current signal included in the range 4…20mA. The use of digital devices allows
obtaining an excellent precision and stability in time. User can set the 4…20mA (or
20…4mA) output into any temperature range in the measuring range included in the
measuring range of the single thermocouple with a minimum range of 50°C. The
range and type of thermocouple are set by simply using one button. A led indicates
the alarm situation (broken or not connected sensor) and it helps user during the
programming. Moreover, transmitters are protected against polarity inversions.
HD778TR1 is specifically designed to be installed in DIN B type connection heads,
HD978TR1 and HD978TR2 are suitable for mounting on 35 mm DIN bars. Beyond
4…20mA output, HD978TR2 has a 3½ digit (Height 10 mm) display which allows
displaying the measured temperature.

TECHNICAL DATA @ 25°C e 24Vdc
INPUT HD778TR1 HD978TR1 HD978TR2
Sensor Thermocouple type K, J, T and N
Connection 2 wires passive transmitter
Measuring range
Thermocouple K: -200°C … +1200°C
Thermocouple J: -200°C … +800°C
Thermocouple T: -200°C … +300°C
Thermocouple N: -200°C … +1200°C
Linearization EN 60584-1-2
ASTM E 230 – ANSI (MC96-1)
Default range Tc = K – Range = 0…1000°C
Minimum measuring range 50°C
Conversion speed 2 measures per second
Accuracy ±0,04%FS±0,04% of the reading or 0.5°C
(the greater of the two values)
Operating temperature of the
cold junction -30 … +80°C 0 … +70°C
Operating temperature -30 … +80°C 0 … +70°C
Storage temperature -40…+80°C
OUPUT
Type of ouput (note 1) 4…20 mA (or 20…4 mA) two wires
22 mA if sensor is broken or not connected
Resolution 4 μA
4 μA
Display:
0,1°C T<200°C
1°C T>200°C
Power voltage 9…30V cc (protection against polarity inversion)
Sensitivity to Vdc power voltage
variations 0,4 μA/V
Load resistance RLMax = (Vdc-9)/0.022
RLMax = 625Ω with Vcc = 24 Vdc
Input/output galvanic insulation 50Vcc (verified at 250V)
Red led It turns on while programming, when the probe is
broken or not connected
Heating time 2 minutes
Note 1) If the measured temperature T goes out of the T1…T2 (T1<T2) set range,
the transmitters linearly regulate the current for T<T1 and T>T2 for an
interval of 10°C. (See the current diagram).
Installation and connection
Fig. 1 shows the mechanical dimensions of the HD778TR1 transmitter and highlights
the holes of 5 mm diameter for fastening the DIN head and the central hole for the
entrance of the wires in the thermocouple. Fig. 1 reports the mechanical dimensions
of the HD978TR1 and of the HD978TR2.
The width of the HD978TR1 is a DIN (17,5 mm) module, the HD978TR2 is a 2
DIN (35mm) modules. The working temperature should be included in operating
temperature declared. Fig. 4 and 5 report the wiring diagrams of the HD778TR1,
HD978TR1 and HD978TR2. In order to obtain the maximum precision, the connection
to the thermocouple should not exceed 3 meters long. In the diagrams reported, the
RL (Load) symbol represents any device introduced in the current loop, that is to say
any indicator, controller, data logger or recorder.
CHOICE OF TYPE OF THERMOCOUPLE
The transmitter accepts four types of thermocouple. The thermocouple set is
highlighted by the number of flashes of the led when power is supplied.
N° of led flashes Type ofthermocouple
1 K
2 J
3 T
4 N
Transmitters come with the default set K thermocouple and range 4…20mA =
0…1000°C.
User can change the thermocouple type and the operating range according to the
following procedure.
Note: after changing the thermocouple type the operating range should be
programmed.

Giving power to the transmitter, the led flashes for a number of times equal to the
type of thermocouple previously configured.
In order to change the setting, remove and reapply supply to the transmitter by
keeping the button pressed.
This way you enter the programming for choosing the type of thermocouple: if you
chose the thermocouple K, the led flashes once.
If you release the button and press it again within 10 seconds, the led flashes twice:
thermocouple J has been chosen.
If you press the button within 10 seconds, the led flashes 3 times: thermocouple T
has been chosen.
If you press the button within 10 seconds, the led flashes 4 times: thermocouple N
has been chosen.
If you press the button within 10 seconds again, the led flashes once indicating that
you chose thermocouple K again and the cycle re-starts.
In order to save the selected type of thermocouple, wait for 15 seconds without
touching any key: the transmitter saves the type of thermocouple and exits
programming, the led flashes for the number of times equal to the type of
thermocouple selected.
If you changed the type of thermocouple, you have to re-programme the
operating range: see paragraph “Programming the operating range”.
HD978TR2
This transmitter has a double dip-switch for selecting the type of thermocouple. The
selection must be set before ignition and is acquired when the instrument is on: a
change in the dip-switch when the instrument is powered has no effect until
the next power cycle.
Procedure:
when the instrument is off, select the type of thermocouple by setting the switches
as shown in the figure below.

By powering the transmitter, the led flashes for a number of times equal to the type
of thermocouple selected.
If you changed the type of thermocouple, you have to re-programme the
operating range: see paragraph “Programming the operating range”.
Programming of the operating range
Transmitters HD778TR1, HD978TR1 and HD978TR2 are supplied by default with
K type thermocouple and range 0…1000°C. The user can set a different range
according to his requirements with a minimum span of 50°C. The correspondence
between the read temperature and the output current can be direct (e.g. 4mA = 0°C
and 20mA = 1000°C) or inverse (e.g. 4mA = 1000°C and 20mA = 0°C).
Acquire the following tools for programming:
• 9…30 Vdc direct current power source,
• thermocouple calibrator,
• copper connection cables
• precision ammeter with 0…25 mA minimum range.

Instead of the thermocouple calibrator, you can use the Delta Ohm HD778-TCAL: this
instrument has to be connected to a serial port of the PC and, by means of a proper
software, automates all the steps described below for programming the operating
range.
If you have a thermocouple calibrator, the steps are:
in order to set the type of thermocouple, proceed as described in the paragraph
“CHOICE OF THE TYPE OF THERMOCOUPLE”.
The voltage values generated by the calibrator must be uncompensated.
The setting must be done with the instrument already powered.
Set the calibrator with the output of the desired type of thermocouple (K, J, T o N),
connect the calibrator to the transmitter thermocouple input according to the
polarity. (Pay attention to polarity).
Set the calibrator so that it generates the voltage corresponding to the temperature
at 4mA, wait for 30 seconds for the voltage to stabilise.
Press and hold the button until the led flashes. Release the button. The instrument
has acquired the first value of the transmitter working range, the led keeps on

flashing. The instrument is now awaiting the second data of the full scale range.
Set the calibrator in order to generate a voltage corresponding to the temperature
at 20mA.
Press and hold the button until the led stops flashing.
Release the button and wait 20 seconds, without changing the calibrator’s data,
so that the transmitter saves the calibration data and is ready for working
normally. The operation ends with a flashing of the led.
The instrument has acquired the second point corresponding to the range you want
to set and is working normally.
The minimum value accepted by the instrument span is 50°C. If the user tries
to insert a second value T2 with (T2-T1)<50, after entering the first value T1 of
the range, the instrument does not accept it and remains in standby while the
led flashing continuously.
The HD778-TCAL is supplied with its software. Connected to the HD778-TCAL
serial output of a PC, the user can configure the transmitter by following
the instructions on the screen.
ORDERING CODES
HD778TR1: 4…20mA/20…4mA 2 wire temperature transmitter for K, J, T and
N thermocouples, configurable with minimum amplitude range 50°C, in a
container for DIN B 43760 heads.
HD978TR1: 4…20mA/20…4mA 2 wire temperature transmitter for K, J, T and
N thermocouples, configurable with minimum amplitude range 50°C, in a
container for 17,5 mm DIN bar connection, dimension 1 module.
HD978TR2: 4…20mA/20…4mA 2 wire temperature transmitter for K, J, T and
N thermocouples, configurable with minimum amplitude range 50°C, in a
container for 35 mm DIN bar connection dimension 2 modules, with 3½ digit
display, height 10 mm.
HD778-TCAL: power generator in the range -60mV…+60mV, regulated by PC
through RS232C serial port, DELTALOG7 software for setting K, J, T and N
thermocouple transmitters.

Download

Manuals and Brochures here.  

HD778TR1_2.pdf

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