Omega CN3440 4.6Input Connections, 4.6.1Thermocouple THC Inputs - Fig, …4 ELECTRICAL INSTALLATION

…4 ELECTRICAL INSTALLATION

4.6Input Connections

Make connections to each input, as shown in Figs 4.4 to 4.14, first removing any factory-fitted wire links not required.

4.6.1Thermocouple (THC) Inputs – Fig. 4.7

Note. Automatic Cold Junction Compensation (ACJC) is active when an input is programmed for use with thermocouples. Use the correct compensating cable between the THC and the terminals – see Table 4.2.

If an external fixed cold junction is used, the connections to the instrument must be made with copper cable. The input must be programmed for mV input signals and the appropriate THC linearizer selected – see Sections 4.5 and 4.6 of the Programming Guide.

Type of		Compensating Cable
Thermocouple	BS1843	ANSI	DIN	BS4937
		MC 96.1	43714	Part No.30
	+ Brown	+ Yellow	+ Red	+ Green
Ni-Cr/Ni-Al (K)	– Blue	– Red	– Green	– White
	Case Red	Case Yellow	Case Green	Case Green *
	+ Orange	+ Orange		+ Pink
Nicrisil/Nisil ( N)	– Blue	– Red	—	– White
	Case Orange	Case Orange		Case Pink *
	+ White	+ Black	+ Red	+ Orange
Pt/Pt-Rh (R and S)	– Blue	– Red	– White	– White
	Case Green	Case Green	Case White	Case Orange *
	+ White	+ Blue	+ Red	+ Brown
Cu/Cu-Ni (T)	– Blue	– Red	– Brown	– White
	Case Blue	Case Blue	Case Brown	Case Brown *
	+ Yellow	+ White	+ Red	+ Black
Fe/Con (J)	– Blue	– Red	– Blue	– White
	Case Black	Case Black	Case Blue	Case Black *
			* Case Blue for intrinsically safe circuits
			DIN 43710
Fe/Con (DIN 43710)	—	—	+ Blue/red	—
			– Blue
			Case Blue

Table 4.2 Thermocouple Compensating Cables

4.6.23-lead Resistance Thermometer (RTD) Inputs – Fig. 4.8

The three leads must have equal resistance, not exceeding 50Ω each.

4.6.32-lead Resistance Thermometer (RTD) Inputs – Fig. 4.9

If long leads are necessary it is preferable to use a 3-lead RTD. If the RTD is to be used in a hazardous area a 3-lead RTD must be used.

4.6.4Links for Unused Inputs

To reduce susceptibility to electro-magnetic interference, ensure that the three terminals on each unused input are shorted together with sleeved wire links.

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