Emerson 3000 World Class, Instruction Bulletin, Table B-1.Specifications for Heater Power Supply

World Class 3000

Instruction Bulletin

Appendix B Rev. 2.3 May 2005

Table B-1. Specifications for Heater Power Supply

Environmental Classification	NEMA 4X (IP56) Optional - Class 1, Division 1,
	Group B (IP56)
Electrical Classification	Category II
Humidity Range	95% Relative Humidity
Ambient Temperature Range	-20° to 140°F (-30° to 60°C)
Vibration	5 m/sec2, 10 to 500 xyz plane
Cabling Distance Between HPS 3000 and Probe	Maximum 150 feet (45 m)
Cabling Distance Between HPS 3000 and CRE 3000	Maximum 1200 feet (364 m)
Cabling Distance Between HPS 3000 and IFT 3000	Maximum 1200 feet (364 m)
Approximate Shipping Weight	12 pounds (5.4 kg)

B-2 THEORY OF OPERATION

The HPS 3000 Heater Power Supply may per- form slightly different functions, depending upon which electronics package it is used with. Figure B-3 shows a functional block diagram of the unit. The HPS contains a transformer for con- verting line voltage to 44 volts needed to power the probe heater. The relay, Figure B-3, can be used to remotely turn the probe on or off manu- ally. A triac module is used to turn the heater on or off, depending on probe temperature.

When used with the CRE 3000 Control Room Electronics or IFT 3000 Intelligent Field Trans- mitter, the HPS uses a cold junction tempera- ture compensation feature. This allows for the

	LINE
	RELAY
	TRIAC
FROM		AD590
IFT		PROBE TC
		STACK TC
		CELL MV

use of a less expensive cable between the HPS and CRE or HPS and IFT. The HPS and elec- tronics package can be located up to 1200 feet (364 m) apart.

The standard cable, between probe and HPS, is thermocouple compensated. This prevents the additional junctions between thermocouple and cable from producing a voltage which would af- fect the thermocouple output signal. A tem- perature sensor in the HPS monitors the temperature at the junction and sends a voltage signal to the CRE and IFT. The CRE and IFT uses this signal to compensate the probe ther- mocouple reading for the temperature at the junction between the compensated and uncom- pensated cables.

TO HEATER

TO

PROBE

PROBE TC

STACK TC

CELL

686015

Figure B-3. Heater Power Supply Block Diagram

Rosemount Analytical Inc. A Division of Emerson Process Management Appendices B-3