Brooks Instrument MT3809E - Manual (Page 37)

2-9
Models MT 3809 & 3819
Section 2 Installation Installation and Operation Manual
X-VA-MT3809-3819
Part Number: 541B049AHG
September, 2008
All internal parameters can be accessed over the HART communications
channel, including the configuration of the output signals used for alarms
and pulse output. An external termination box is attached for easy hookup
of these signals. The alarms are configurable as normally open or normally
closed.
The alarm contact and pulse output digital signals are electrically identical,
independent, optically coupled transistor outputs. Wiring will be as required
by the external driven system— Prover, DCS/PLC, terminal-automation
system, batch controller etc. These can be wired as an open collector or
open emitter signal on the high or low side of voltage-rail within the
receiving equipment, depending upon the signal needs. When interfacing
to external electronics, be careful to work within the voltage/current polarity
and limits as specified in Section 1.
To install the typical transmitter alarms and/or pulse digital outputs
configuration:
1. Intrinsically safe installations require the use of barriers, power supply
limits and cable parameters as shown in the installation diagram. All
connections are made in the terminal box attached to the back of the
transmitter housing. Refer to Figures 1-4 and 1-8.
2. If the area classification is Division 2, a barriers are not required and
cable parameters are not applicable. However, the electrical code will
require the use of conduit for wire protection. Refer to Figures 1-4 and
1-8.
3. If the installation is to be protected by Division 1 explosion proof
methods, the optional explosion proof enclosure is required and
explosion proof installation methods must be followed. Refer to Figures
1-5 and 1-8.
4. It is highly recommended that shielded cable be used for hook up. The
shield should be connected to chassis ground at the transmitter end
and should be taped up and not connected at the receiver end.
Insulation of the shield at the receiving end is especially important for
intrinsically safe installations.
5. The maximum resistance of the loop resistor, the associated cable and
the barrier is determined by the power supply voltage and is shown
graphically in Figure 1-2.
6. The pulse and alarm outputs function as isolated switch closures
(optically isolated open collector-emitter) and must be supplied with a
power source, as shown in wiring diagram, Figure 1-4. Observe polarity
and do not exceed 30 Volts for the supply and limit load current to 20
mA for each output.
7. The zero function is activated by momentarily shorting the zero
terminals on the wiring block. This may be accomplished with any
conductive jumper or a switch which can be remotely mounted. The
hazardous area classification will determine the wiring methods used
for this switch.