Endress+Hauser iTEMP TMT182, Руководство по эксплуатации

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4 Wiring TMT182
14 Hauser
4.3 Potential grounding
!
Note!
Please take note of the following when remotely installing the head transmitter in a field housing.
The shield on the output (output signal 4 to 20 mA) must be at the same potential as the shield at
the sensor connection.
For an effective shielding the cable shield must be solidly connected to the field housing. This can
be achieved by connecting the cable shield to the special EMC cable gland.
Open the field housing cable gland and connect the shield of the out-
put and sensor connection according to the figure opposite (see fig. 9)
When using grounded thermocouples, shielding of the output cable
(4 to 20 mA cable) is recommended.
In plants with strong EMC problems shielding of all cables with a low
ohm connection to the transmitter housing is
recommended.
ƒig. 9:: Shielding on remote installation
4.4 Ground the Transmitter
The transmitter will operate with the current signal loop either floating or grounded. However, the
extra noise in floating systems affects many types of readout devices. If the signal appears noisy or
erratic, grounding the current signal loop at a single point may solve the problem. The best place to
ground the loop is at the negative terminal of the power supply. Do not ground the current signal
loop at more than one point. The transmitter is galvanically isolated to 2 kV AC (from the sensor
input to the output), so the input circuit may also be grounded at any single point. When using a
grounded thermocouple, the grounded junction serves as this point.
5 Operation
5.1 Communication
The temperature head transmitter is set up using the HART
®
protocol. The values measured can
also be read using the HART
®
protocol. In order to do this the user has two possibilities:
• Operation using a universal hand operated module “HART
®
Communicator DXR275, DXR375”.
• Operation using a PC and operating software (e.g. Commuwin II) as well as a HART
®
modem
(e.g. “Commubox FXA191”).
5.1.1 HART
®
Communicator DXR275, DXR375
Selection of the unit functions using the “HART
®
Communicator” is done using various menu
levels as well as with the help of a special HART
®
function matrix (see page 18).
!
Note!
• When using the HART
®
hand unit all parameters can be read out, however, programming is
locked. It is possible to access the HART
®
function matrix by entering 281 in the LOCK function.