Prepare The Electrical Connections - Emerson Rosemount 5408 Quick Start Manual

Quick Start Guide
8

Prepare the electrical connections

8.1 Cable selection
RS-485 bus
Power
supply
Use wire rated at least 5 °C above maximum ambient temperature.
8.2 Cable gland/conduit
For explosion-proof/flameproof installations, only use cable glands or
conduit entry devices certified explosion-proof or flameproof.
8.3 Grounding
Make sure grounding is done according to national and local electrical
codes. Failure to do so may impair the protection provided by the
equipment.
Transmitter housing
The most effective grounding method is direct connection to earth ground
with minimal impedance. There are two grounding screw connections
provided (see
Figure 8-1: Ground Screws
A. Internal ground screw
B. External ground screw
Cable shield grounding
Make sure the instrument cable shield is:
• Trimmed close and insulated from touching the transmitter housing.
• Connected to a good earth ground at the power supply end.
16
Use shielded twisted pair wiring with a characteristic
impedance of 120 Ω (typically 24 AWG).
Use 24-14 AWG wire. Twisted pairs and shielded wiring are
recommended for environments with high EMI
(electromagnetic interference).
Figure 8-1).
February 2020
Rosemount 5408 Level Transmitter