Wiring - Emerson Rosemount 248 Reference Manual

Reference Manual
00809-0100-4825, Rev CB
Note
Microprocessor failures cause high alarm regardless of alarm direction (high or low) choice.
The values the transmitter drives its output in failure mode depend on if it is configured to
standard, NAMUR-compliant, or custom operation. See
page 52
2.6

Wiring

All power to the transmitter is supplied over the signal wiring. Ordinary copper wire of sufficient
size should be used to ensure the voltage across the transmitter power terminals does not drop
below 12.0 Vdc. Verify that the operating atmosphere of the transmitter is consistent with the
appropriate hazardous locations certifications. Always use extreme caution when making
contact with the leads and terminals.
If the sensor is installed in a high-voltage environment and a fault condition or installation error
occurs, the sensor leads and transmitter terminals could carry lethal voltages. Use extreme
caution when making contact with the leads and terminals.
Note
Do not apply high voltage (e.g., ac line voltage) to the transmitter terminals since high voltage
can damage the unit. (Sensor and transmitter power terminals are rated up to 42.4 Vdc.) Use
extreme caution when making contact with the leads and terminals.
For multichannel installations, see
and thermocouple types. Refer to
Use the following steps to wire the transmitter:
1.
2.
3.
4.
5.
Installation
for standard and NAMUR-compliant operation parameters.
Remove the terminal block cover (if applicable).
Connect the positive power lead to the "+" terminal. Connect the negative power lead
to the "–" terminal (see Figure
the leads and terminals.
Tighten the terminal screws.
Reattach and tighten the cover (if applicable). All connection head covers must be fully
engaged to meet explosion-proof requirements
Apply power (see "Power
"Software detected failure mode" on
page 14. The transmitters accept inputs from a variety of RTD
Figure 2-7 on page 16 when making sensor connections.
2-6). Use extreme caution when making contact with
.
supply").
Section 2: Installation
March 2014
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