Brooks Instrument MT3810 - Manual (Page 33)

2-7
Installation and Operation Manual
X-VA-MT3810-eng
Part Number: 541B050AHG
June, 2008
Model MT 3810
Section 2 Installation
Typically applications require only the use of the 2 wire loop analog signal.
In some applications where transmitters and actuators are widely sepa-
rated (e.g. tank farms), devices are wired in a multi-drop configuration to
save wiring costs. Each unit is given an individual HART address in the
range of 1-15 to distinguish each unit during communications over a
common wire pair. In this configuration, the 4-20 mA output signal cannot
be used.
To install the typical transmitter analog output configuration:
1. For intrinsically safe installation, intrinsic safety barrier selection, cable
parameters, and power supply limits must be in accordance with the
entity parameters shown in Figure 1-3. Alternatively, the optional
intrinsically safe power supply available from Brooks may be used.
Cable parameters for inductance and capacitance still apply.
2. If the area classification is Division 2, a barrier is not required and cable
parameters are not applicable. The electrical code will require the use
of conduit for wire protection. Refer to Figure 1-3.
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 Fig.1-5.
4. 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. After installation and powering of the loop, the transmitter must be
zeroed, both electrically and mechanically. This operation will
compensate for any stray magnetic effects in the vicinity of the
transmitter. Flow must be verified to be zero when the zero function is
momentarily activated.
With the float at the zero flow position, set zero flow by either shorting
the two pins together at the terminal block. If desired, a zero switch can
be remotely mounted and wired to these terminals. The hazardous area
classification will determine the wiring methods used for this switch.
The pointer must also be adjusted to the reference line on the scale
using the adjustment screw on the face of the pointer, next to the hub.
The zero function may be activated as part of a periodical maintenance
check.