Brooks Instrument MT3809E - Manual (Page 39)

2-11
Models MT 3809 & 3819
Section 2 Installation Installation and Operation Manual
X-VA-MT3809-3819
Part Number: 541B049AHG
September, 2008
1. The inductive alarms can be supplied as a stand alone option or
combined with the transmitter. When stand alone, connections to the
alarms are made inside the indicator housing. When supplied in
combination with the transmitter, connections are made inside the
auxiliary terminal box attached to the indicator housing.
Refer to Fig. 1-7 for stand alone inductive alarm installation and to
Figures 1-6 and 1-8 for installation with the transmitter combined with
the inductive alarms.
2. Intrinsically safe installations require the use of relay isolators for the
alarms and a barrier for the transmitter, if equipped. Power supply limits
and cable parameters must be as shown in the installation diagram.
3. If the area classification is Division 2, the transmitter barrier and cable
parameters are not applicable. However for proper operation of the
inductive alarms, the relay isolators must be used. The electrical code
will require the use of conduit for wire protection.
4. If the installation is according to Division 1 explosion proof methods, the
optional explosion proof enclosure is required and explosion proof
installation methods must be followed. For proper operation of the
inductive switches, the relay isolators must be used.
5. It is highly recommended that shielded cable be used for hook up. The
shields should be connected to chassis ground at the transmitter/alarm
end and should be taped up and not connected at the receiver end. The
taping and insulation of the shields at the receiving end is especially
important for intrinsically safe installations.
6. For the transmitter output, if supplied, 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.
7. The relay isolator has built in power handling contacts. Refer to the
specifications for these ratings.
8. If desired, the transmitter zero function can be remotely mounted using
a momentary contact switch. Follow the same wiring practices as used
for the other outputs.
9. 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 zero when the zero function is activated,
using the remote switch or shorting the zero terminals. 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.
10.Under actual flow conditions, verify that the transmitter output matches
the mechanical pointer position. If a discrepancy is noted with the
transmitter, the HART communications channel can be used to verify or
adjust the transmitter settings. The Emerson Model 275 hand-held
communicator provides a simple means to accomplish this check
anywhere in the loop. Refer to Figure 3-2 for connection instructions.
11.Proper operation of the inductive alarms can be determined by manually
rotating the mechanical pointer and observing the status lights on the
relay isolator. The small alarm pointers indicate the alarm trip points.
Changes to the set points can be made by loosening the pointer screws
and repositioning the pointers.