SMAR ld301, Operation And Maintenance Instruction Manual

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LD301 – Operation and Maintenance Instruction Manual
1.6
NOTE
The transmitters are calibrated in the vertical position and a different mounting position displaces
the zero point. Consequently, the indicator will indicate a different value from the applied pressure.
In these conditions, it is recommended to do the zero pressure trim. The zero trim is to compensate
the final assembly position and its performance, when the transmitter is in its final position. When
the zero trim is executed, make sure the equalization valve is open and the wet leg levels are
correct.
For the absolute pressure transmitter, the assembly effects correction should be done using the
Lower trim, due to the fact that the absolute zero is the reference for these transmitters, so there
is no need for a zero value for the Lower trim.
When the sensor is in the horizontal position, the weight of the fluid pushes the diaphragm down,
making it necessary a Lower Pressure Trim.
Fig.1.7 - Sensor Positions
Connection of the LD301 working as transmitter should be done as in Figure 1.8.
Connection of the LD301 working as a controller should be as indicated in Figure 1.9.
Connection of the LD301 in multidrop configuration should be done as in Figure 1.10. Note that a
maximum of 15 transmitters can be connected on the same line and that they should be connected in
parallel.
Take care to the power supply as well, when many transmitters are connected on the same line.
The current through the 250 Ohm resistor will be high causing a high voltage drop. Therefore make
sure that the power supply voltage is sufficient.
The Hand-Held Terminal can be connected to the communication terminals of the transmitter or at any
point of the signal line by using the alligator clips. It is also recommended to ground the shield of
shielded cables at only one end. The ungrounded end must be carefully isolated.
NOTE:
Make sure that the transmitter is operating within the operating area as shown on the load curve (Figure 1.11).
Communication requires a minimum load of 250 Ohm.
DIAPHRAGM SENSOR
SENSOR IN THE VERTICAL POSITION
SENSOR IN THE HORIZONTAL POSITION
HEAD OF THE FLUID
DIAPHRAGM SENSOR