Omega CL526 User Manual
20
7
ELECTRICAL CONNECTIONS
Appropriate extension wires should be used between the thermocouple (or instrument under calibration) and the CL526
unless the thermocouple leads permit direct connection.
Make sure that both thermocouple and compensating cable are connected with the correct polarity.
If in doubt, the polarity of the compensating leads can be checked by connecting a length of lead to the indicator,
shorting the free ends of the wires together and noting that the indicator reading increases when the wires connection
is heated.
Color codes of compensating cables change in different countries. Check the appropriate table.
For Rtd connection use a cable of adequate gauge to lower the overall input resistance.
The use of a cable with a good resistance balance between conductors is also necessary.
unless the thermocouple leads permit direct connection.
Make sure that both thermocouple and compensating cable are connected with the correct polarity.
If in doubt, the polarity of the compensating leads can be checked by connecting a length of lead to the indicator,
shorting the free ends of the wires together and noting that the indicator reading increases when the wires connection
is heated.
Color codes of compensating cables change in different countries. Check the appropriate table.
For Rtd connection use a cable of adequate gauge to lower the overall input resistance.
The use of a cable with a good resistance balance between conductors is also necessary.
Table A
Colour code & polarity for extension wires
Thermocouple
Wires
Colour
code
E Chromel
( + )
Chromel
Purple
Constantan
( - )
Constantan
Red
J
Iron
( + )
Iron
White
Constantan
( - ) Constantan
Red
K
Chromel
( + )
Chromel
Yellow
Alumel
( - ) Alumel
Red
R
Pt 13% Rh
( + )
Copper
Black
Platinum
( - )
Alloy 11
Red
S
Pt 10% Rh
( + )
Copper
Black
Platinum
( - )
Alloy 11
Red
T
Copper
( + )
Copper
Blue
Constantan
( - )
Constantan
Red
B
Pt 6% Rh
( + )
Copper
Pt 30% Rh
( - )
Copper
N
Nicrosil
( + )
Nicrosil
Orange
Nisil
( - )
Nisil
Red
7.1
Wiring practice
Although the CL526 portable calibrator is designed to be insensitive to transients or noise, the following
recommendations should be followed to reduce ac pick up in the signal leads and to ensure good performance.
The input leads should not be run near ac line wiring, transformers and heating elements.
Input/output leads should, if possible, be twisted and shielded with the shield grounded at the end of the cable.
When shielded cables are used the shield must be connected to the positive terminal.
Above figure shows some examples of input/output wiring and connections.
recommendations should be followed to reduce ac pick up in the signal leads and to ensure good performance.
The input leads should not be run near ac line wiring, transformers and heating elements.
Input/output leads should, if possible, be twisted and shielded with the shield grounded at the end of the cable.
When shielded cables are used the shield must be connected to the positive terminal.
Above figure shows some examples of input/output wiring and connections.