Emerson 644 manual Wiring, Power terminals does not drop below 9 Vdc

Reference Manual

00809-0400-4728, Rev AA June 2011

Rosemount 644

WIRING	All power to the transmitter is supplied over the signal wiring. Use ordinary
	copper wire of sufficient size to ensure that the voltage across the transmitter
	power terminals does not drop below 9 Vdc.

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. Abnormally high voltage can damage the unit. (Sensor and transmitter power terminals are rated to 42.4 Vdc. A constant 42.4 volts across the sensor terminals may damage the unit.)

The transmitters will accept inputs from a variety of RTD and thermocouple types. Refer to Figure 2-5 on page 2-7when making sensor connections. Refer to Figure 2-6 on page 2-8for FOUNDATION fieldbus installations.

Use the following steps to wire the power and sensor to the transmitter:

1.Remove the terminal block cover (if applicable).

2.Connect the positive power lead to the “+” terminal. Connect the negative power lead to the “–” terminal (see Figure 2-7).

3.Tighten the terminal screws. When tightening the sensor and power wires, the max torque is 6-in.-lbs (0.7 N-m).

4.Reattach and tighten the cover (if applicable).

5.Apply power (see “Power Supply”).

Figure 2-5. Transmitter Power,

Communication, and Sensor

Terminals

644H

Sensor
Terminals
Communication	1	2	3	4
Terminals

Power Terminals

2-7