The maximum separation distance between the sensor and the transmitter is limited by
the resistance of the connecting wiring, which is a function of the gauge of wire being
used. Net Safety recommends that sensor separation must not exceed 2000 feet (610
meters) while using 16 AWG (1.31 mm
2
) wire. Refer to Chapter 7 for wire gauges and
resistance values.
Note
When the sensor is separated from the transmitter, always ensure that the transmitter is supplying
the required voltage to the sensor terminals inside the junction box. If the 4-20 mA signal is not used,
connect a jumper between the 4-20 terminal and the COM terminal on the transmitter terminal
board.
2.5.4 Board assembly
There are three different fixed boards and a relay board which make up the PCB assembly.
Simply loosen the three locking standoffs, remove one board, insert the other board and
tighten screws. The boards are susceptible to ESD. Refer to Chapter 6 for further
information on proper handling of this equipment.
Millennium transmitter module boardsFigure 2-7:
2.5.5 Installation to transmitter or junction box
The APM sensor is supplied with a 3/4” NPT male conduit connection and is intended to be
mounted directly to an available 3/4” NPT conduit entry on the Millennium transmitter or
remotely using the supplied junction box.
The sensor should be tightly threaded to the transmitter or junction box. A minimum of
seven (7) threads need to be engaged to ensure proper water ingress protection and the
explosion proof rating of the devices. Proper care needs to be taken to ensure that no
damage is caused to the wires on the APM sensor and circuit board inside the transmitter
and junction box.
Installation
11
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