ZET 7X20 TROUBLESHOOTING

Diagrams of connecting the ZET 7020 and ZET 7120 measuring units to thermocouples and the measuring line:

1. Check the offset voltage (2.5±0.1) V

Using a tester, check voltage between the “blue” output and the “common” output (white-orange).

2. Check the thermocouple resistance.

Deenergize ZET 7X20 and measure resistance between the “red” and “blue” outputs. The resistance must be within 10 to 20 Ohm at ambient temperature.

Use only thermally-compensated cable for extending the cable between the TC and ZET 7X20.

3. Thermocouple screening

If it’s impossible to measure the temperature accurately due to EMI, the TC needs screening. Connect the TP cable screen through a 15 nF 500 V condenser to the “Common” output for the measuring circuit power supply, as shown in the figure below: