Emerson 4500 manual Connect Wiring and Power Up, Hart Terminal Blocks

Reference Manual

00809-0100-4027, Rev AA December 2005

Rosemount 4500

Connect Wiring and Power Up

Wiring for HART Protocol

NOTE

Use shielded twisted pairs to yield best results. To ensure proper communication, use 24 AWG or larger wire, and do not exceed 5000 feet (1 500 meters).

Figure 2-5. HART Terminal

Blocks

ALARM

SECURITY

-LOOP

+LOOP

SPAN

ZERO

-LOOP

+LOOP

4500_25_AA.EPS

To make connections, perform the following procedure:

1.Remove the housing cover.

2.Connect the positive lead to the terminal marked (+) and the negative lead to the terminal marked (pwr/comm –).

3.Tighten cord grip to avoid moisture accumulation in the terminal compartment.

Signal Wiring Grounding

Do not run signal wiring in conduit or open trays with power wiring, or near heavy electrical equipment. Ground the signal wiring at any one point on the signal loop, or leave it ungrounded. The negative terminal of the power supply is a recommended grounding point.

Power Supply 4–20 mA Transmitters

The dc power supply should provide power with less than two percent ripple. Total resistance load is the sum of resistance from signal leads and the load resistance of the controller, indicator, and related pieces. Note that the resistance of intrinsic safety barriers, if used, must be included.

See load limitations in Section A: Reference Data.

NOTE

A minimum loop resistance of 250 ohms is required to communicate with a HART Communicator. If a single power supply is used to power more than one 4500 transmitter, the power supply used and circuitry common to the transmitters should not have more than 20 ohms of impedance at 1200 Hz.

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