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4-10 | Thermox Series 2000 WDG-IV / IVC / IVCM

Determining temperature

If you take the displayed cell temperature and divide it by the T/C Ratio in memo-

ry location 88, you will have the actual furnace set point control temperature.

You can use a Type-K table to measure the voltage on terminals C and D on

the sensor board, and add the appropriate amount of mVs for the board ambi-

ent. The corresponding temperature from a Type-K thermocouple should be the

actual furnace set point temperature = 695°C / T/C Ratio (memory location 88).

Use the Type-K table to determine the mV change you have for 273°C and add

this mV change for the actual board temperature. This should be the compensa-

tion voltage measured between D+ and 6- on the sensor board. So for a 50°C

ambient at the board, the voltage should be 11.05 mV (273°C) + 2.02 mV (50°C)

= 13.07 mVs.

If you have a T/C ratio of 0.9, the corresponding furnace temperature set point

should be (695°C / 0.9 = 772°C). If you measure the voltage at terminals C and D

on the sensor board with a 50°C ambient, the voltage should be 32.125 (772°C)

- 2.02 mV (50°C) = 30.1 mV. If you add in the compensation voltage for 50°C, the

voltage at terminals 5 and 6 should be 30.1 mV + 12.05 mV = 42.15 mVs which

should also be the voltage that you measures at T/C+ and T/C - terminals on the

Series 2000 wiring card terminals and also the displayed T/C mV value that you

can set one of the display lines to view in the Setup key - Display menu.

T/C Ratio Adjustment Limits for Primary Calibration

Cell Temp °C Max T/C Ratio Min T/C Ratio

615 1.3 0.7

650 1.24 0.74

695 1.22 0.777

824 1.139 0.861

790 same as 824°C

Table 4-2.

For a cell operating temperature of 695°C, the T/C ratio low limit is .777 and the

high limit is 1.222, which corresponds to a thermocouple indicated temperature

range of 540°C to 848°C.

• If you nd that a regular calibration isn’t working correctly, rst check that

your calibration gas values match the values written on the gas cylinders;

also be sure that the correct ow of gases has been set and that the gases

are allotted enough time to ow through the sensor. Only if these checks

have been done and the system still can’t be properly calibrated should you

perform a primary calibration.

Ametek Thermox Series 2000 WDG-IVC User Manual

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