Wiring - Emerson Rosemount 248 Reference Manual

Installation
May 2019
These values are also custom configurable by the factory or using the Field Communicator
or AMS Device Manager. See for instructions on how to change the alarm and saturation
levels with the Field Communicator.
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.
2.9

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.
CAUTION
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
inputs from a variety of RTD and thermocouple types. Refer to
sensor connections.
Use the following steps to wire the transmitter:
Procedure
1. Remove the terminal block cover (if applicable).
2. Connect the positive power lead to the "+" terminal. Connect the negative power
3. Tighten the terminal screws.
4. Reattach and tighten the cover (if applicable). All connection head covers must be
5. Apply power (see
20
lead to the "–" terminal (see
with the leads and terminals.
fully engaged to meet explosion-proof requirements.
Power
Multichannel installations. The transmitters accept
Figure 2-9). Use extreme caution when making contact
supply).
Rosemount 248 Temperature Transmitter Reference Manual
Reference Manual
00809-0100-4825
Figure 2-10 when making