7
Figure 6. Contact Noise Suppression
Sensor Placement (Thermocouple or RTD)
If a temperature probe is to be subjected to corrosive
or abrasive conditions, it must be protected by an ap-
propriate thermowell.
Probes must be positioned to reflect the true process
temperature:
1. In a liquid media - the most agitated area
2. In air - the best circulated area
The placement of probes into pipe work some
distance from the heating vessel leads to trans-
port delay, which results in poor control.
For a two wire RTD, a wire link should be used in place
of the third wire (see the wiring section for details). Two
wire RTDs should only be used with lead lengths less
than 3 metres.
Use of three wire RTDs is strongly recommended to
reduce errors do to lead resistance.
Thermocouple Wire Identification
The different thermocouple types are identified by their
wires color, and where possible, the outer insulation
as well. There are several standards in use throughout
the world, but most regions now use the International
IEC584-3 standard.
The table below shows the wire and sheath colors used
for most common thermocouple types. The format
used in this table is:
Table 2. Thermocouple Extension Wire Colors
Type
International
IEC584-3
USA ANSI
MC 96.1
British
BS1843
French
NFC 42-324
German
DIN 43710
J
+*
Black
Black
White
Black
Yellow
Black
Yellow
Black
Red
Blue
-
White
Red
Blue
Black
Blue
T
+
Brown
Brown
Blue
Blue
White
Blue
Yellow
Blue
Red
Brown
-
White
Red
Blue
Blue
Brown
K
+
Green
Green
Yellow
Yellow
Brown
Red
Yellow
Yellow
Red
Green
-*
White
Red
Blue
Purple
Green
N
+
Pink
Pink
Orange
Orange
Orange
Orange
-
White
Red
Blue
B
+
Grey
Grey
Grey
Grey
Red
Grey
-
White
Red
Grey
R & S
+
Orange
Orange
Black
Green
White
Green
Yellow
Green
Red
White
-
White
Red
Blue
Green
White
C (W5)
+
White
White
-
Red
Note:
* = Wire is magnetic
+
Wire
Sheath
-
Wire
Table 2. Thermocouple Extension Wire Colors
Type
International
IEC584-3
USA ANSI
MC 96.1
British
BS1843
French
NFC 42-324
German
DIN 43710
J
+*
Black
Black
White
Black
Yellow
Black
Yellow
Black
Red
Blue
-
White
Red
Blue
Black
Blue
T
+
Brown
Brown
Blue
Blue
White
Blue
Yellow
Blue
Red
Brown
-
White
Red
Blue
Blue
Brown
K
+
Green
Green
Yellow
Yellow
Brown
Red
Yellow
Yellow
Red
Green
-*
White
Red
Blue
Purple
Green
N
+
Pink
Pink
Orange
Orange
Orange
Orange
-
White
Red
Blue
B
+
Grey
Grey
Grey
Grey
Red
Grey
-
White
Red
Grey
R & S
+
Orange
Orange
Black
Green
White
Green
Yellow
Green
Red
White
-
White
Red
Blue
Green
White
C
(W5)
+
White
White
-
Red
*Wire is magnetic. a magnet can be used to assist with correctly identifying the type and polarity of the conductors
Summary of Contents for Chromalox 4081
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