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502 010 05
5 Electrical connections
The figure below shows the terminal board with all the possible electrical connections for the
Flow Transmitter. The program enable switch, SW1 located in the upper left corner, must be
in the ON position when configuring and calibrating the Flow Transmitter. After configuration
and calibration, the switch must be set in the OFF position.
Figure 3: Electrical connections in Terminal Board
5.1
Power supply
The power supply for the Flow Transmitter can be either 24 V DC or 24 V AC. Terminal
boards marked 'PD 381-02' will have a 2-position switch, SW2. If SW2 is set to 'AC' (factory
setting), the supply voltage can be either AC or DC. If SW2 is set to 'DC', it must be supplied
with DC. The 'DC' setting can be used on mobile applications to comply with OIML require-
ments.
If the conductivity for the liquid is below the specified 5 µs/cm, it might still be possible to
measure the flow. To do this, the Flow Transmitter must be connected to a separate DC
power supply with the -24 V DC terminal connected to the piping system.
This will increase the sensitivity, and flow measurement may still be possible.
5.2
Output1
Output1 on the terminal board is a voltage
supply, which can be used to supply an ex-
ternal counter circuit, relays or current de-
vices (4-20 mA).
The voltage at the output can vary from 20
to 40 V DC, depending on the power supply
voltage (Supply voltage - 2 V as minimum).
The voltage supply is connected directly to a bridge circuit, which rectifies the power supplied
to the transmitter. The output is protected with a zener diode and a current-limiting resistor in
the same way as the pulse outputs. Furthermore, the output is isolated from the internal elec-
tronics by a transformer. The output is not isolated from the power source supplying the
transmitter.
20/55
D
zener
51 V
Figure 4: Power supply output electrical
Flow Transmitter, PD 340
6-
Output 1
5+
R PTC
2
+
~
Power
input
-
~
1
Bridge circuit
551 104 01
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