tekmar 091 Sensor Socket - Manual (Page 6)

© 2014 090_D - 01/14
6 of 8
When performing these tests:
The sensor head should be installed in the slab.
The five cable wires at the control should be disconnected.
Use a good quality electrical testing meter with an ohm scale range of 0 to
2,000,000 Ohms.
The sensor has two 10k Ohm thermistors. One reads slab surface temperature, and
the other checks sensor heater temperature.
If the sensor has been disconnected from the control for an hour or more, the readings
for both thermistors should be very close.
Using the ohmmeter and standard testing practices, measure the resistance
between:
(a) the yellow and black sensor wires (sensor temperature), and
(b) the brown and black sensor wires (slab temperature).
The table below lists the expected resistance values at various sensor temperatures.
Measure the resistance between the blue and black wires. When the sensor surface
is dry, the reading should be 2,000,000 Ohms. When the sensor surface is wet it
should be between 10,000 and 300,000 Ohms.
Measure the resistance between the red and black wires of the heating element. This
reading should be close to 50 Ohms.
•
•
•
Temperature Resistance
°F °C
-50 -46 490,813
-45 -43 405,710
-40 -40 336,606
-35 -37 280,279
-30 -34 234,196
-25 -32 196,358
-20 -29 165,180
-15 -26 139,402
-10 -23 118,018
-5 -21 100,221
0 -18 85,362
5 -15 72,918
10 -12 62,465
15 -9 53,658
20 -7 46,218
25 -4 39,913
Temperature Resistance
°F °C
30 -1 34,558
35 2 29,996
40 4 26,099
45 7 22,763
50 10 19,900
55 13 17,436
60 16 15,311
65 18 13,474
70 21 11,883
75 24 10,501
80 27 9,299
85 29 8,250
90 32 7,334
95 35 6,532
100 38 5,828
105 41 5,210
Step 4 - Test the Sensor
Temperature vs. Resistance Table