07AC91 GJR5252300R0101 fault finding: 1, suspected analog output board card problems, using a multimeter to measure the 4-20mA output signal, the signal is normal! 2, began to suspect that the frequency converter control signal inputs have a problem, replaced by an inverter of the same type, is still the case. 3, with a hand-held signal transmitter to do 4-20mA output signal source In order to verify that the analogue 4-20mA output channel, add a signal isolation module TA3012, TA3012 input terminals 5 and 6 to the analogue output module, output terminals 1 and 2 to the inverter, 3 and 2 terminals to the inverter, and 3 and 4 terminals to the inverter. Terminals connected to the frequency converter, 3, 4 terminals connected to the external 24VDC power supply, the frequency converter started normally. 5, it is judged that the root cause of the problem is still caused by the frequency converter interference with the analogue channel.

07AC91 GJR5252300R0101 In the field of high-speed railway automation, Hologic is the main supplier of train safety control systems for 350km/h high-speed railways and 250km/h moving trains. The 350 km/h high-speed railways of Zhengzhou West Line and Guangzhou-Shenzhen-Hong Kong adopt Hologic’s train safety control system. Most of the 250km/h locomotives in operation in China are equipped with Hologic products, and in 2012, the U.S. Locomotive Laboratory also selected Hologic’s self-developed train safety control system equipment.

07AC91 GJR5252300R0101 solution: I believe that many self-control engineers in the debugging system have encountered similar problems, therefore, I would like to share my own system debugging tips. In the PLC and frequency converter used at the same time in the automatic control system, should focus on the following matters:

1, PLC power supply and power system power supply (inverter power supply) are configured separately, and the PLC power supply should choose the isolation transformer;
2, the power line as far as possible separate from the signal line, the signal line should be shielded;
3, whether analogue signal input or analogue signal output, analogue channel always use signal isolation module;
4, PLC programme to do software filtering design;
5, signal ground and power ground separate design.