Reference Manual
00809-0100-4793, Rev CA
August 2004
2-5
Rosemount 8742C
Conduit Cables
Run the appropriate size cable through the conduit connections in your
magnetic flowmeter system. Run the power cable from the power source to
the transmitter. Run the coil drive and electrode cables between the flowmeter
and transmitter.
Prepare the ends of the coil drive and electrode cables as shown in Figure
2-3. Limit the unshielded wire length to 1-inch on both the electrode and coil
drive cables.
NOTE
Excessive lead length or failure to connect cable shields can create electrical
noise resulting in unstable meter readings.
Figure 2-3. Cable Preparation
Detail
Transmitter Coil Input
The Rosemount 8742C Magnetic Flowmeter Transmitter is a four-wire device.
This wiring section covers supplying power to the flowtube coils through the
transmitter. The transmitter coil input power sends a pulsed DC frequency to
the flowtube.
Wire the transmitter according to local electrical requirements. Ground the
transmitter cage via the threaded conduit connection. For ac power
applications, connect ac Neutral to terminal N and connect ac Line to terminal
L1. For dc power applications, properly connect the positive and negative
terminals. Units powered by 15-50 V dc power supply may draw up to 1 amp
of current. In addition, follow the supply wire and disconnect requirements
below:
1.00
(26)
NOTE
Dimensions are in
inches (millimeters).
Cable Shield
8705-0041B
Power Supply (Volts)
1.0
0.75
0.5
0.25
0
15
50
20
30
40
I = 10/V
I = Supply current requirement (Amps)
V = Power supply voltage (Volts)
Supply Current (Amp
s)
Summary of Contents for 8700 Series
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