Martel Electronics MC1200 - Manual (Page 22)

22
temperature, maximum temperature, R0, and the values for each of the
temperature coefficients.
The custom function uses the Calendar-Van Dusen equation for outputting and measuring
custom RTDs. The coefficient C is only used for temperatures below 0°C. Only A and B
coefficients are needed for the range above 0°C, so coefficient C should be set to 0. The
R0 is the resistance of the probe at 0°C. The coefficients for PT385, PT3926, and PT3616
are shown in Table 4 below.
Table 4. RTD Coefficients
RTD Range(°C) R0 Coefficient A Coefficient B Coefficient C
PT385 -260 - 0 100 3.9083x10-3 -5.775x10-7 -4.183x10-12
PT385 0 - 630 100 3.9083x10-3 -5.775x10-7 ---
PT3926 Below 0 100 3.9848x10-3 -5.87x10-7 -4x10-12
PT3926 Above 0 100 3.9848x10-3 -5.87x10-7 ---
PT3916 Below 0 100 3.9692x10-3 -5.8495x10-7 -4.2325x10-12
PT3916 Above 0 100 3.9692x10-3 -5.8495x10-7 ---
5. Using Isolated Measure Modes (Upper Display)
5.1 Measuring volts and mA
Use the following steps to measure the voltage or current output of a transmitter.
1. Select the upper display from the Main Menu.
2. Select the desired primary parameter to be measured. Connect the leads to the isolated
inputs of the calibrator, as in Figure 16.
Figure 16. Isolated Input Connection
5.2 Measuring current with loop power
To test a 2-wire, loop powered transmitter that is disconnected from wiring, use the loop
power function. This function activates a 24V supply in series with the current measuring
circuit. To use this option proceed as follows:
1. Select [mA LOOP] as primary parameter in the upper display.
2. Connect the calibrator to transmitter current loop terminals, as shown in Figure 17.