How to eliminate the voltage between analog output M and ground - Database & Sql Blog Articles

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I use the EM232 analog output voltage 0-10V to control the speed control motor SNT1000E controller; the controller accepts 0-10V voltage to adjust the speed, which is non-isolated design; recently the controller often burned, consulted the manufacturer It is said that there is a voltage between the negative terminal of the analog output and the ground.
It is measured that there is a voltage of about 4.7V between the M and the ground of the EM232 analog output terminal (in the case of no analog voltage output):
How to eliminate the voltage between the M terminal and the ground?
Does the voltage really burn the controller? (plc is not grounded, EM232 module is not grounded)
The power supply of the speed controller is AC 220V, and the power of the analog module is the power provided by the S7-200CPU itself. If the M end is connected to the ground, will it burn the CPU's own power?
A: Your controller is non-isolated, which means that the M point of the AO output is connected to the ground where the controller is located, and the AO output M between the AO output and the ground is 4.7V. This "ground" refers to the location of the location of the AO module.
Then we can know that there is not an equipotential on all parts of your site. If it is necessary to eliminate the voltage between the M terminal and the ground, the most standardized method is to deal with the grounding of the site to ensure that the ground where the AO module and the controller are located is equipotential. It is not possible to directly connect M to the ground where the module is located, because there is a pressure difference between the two points, which will form a circulation and interfere with the signal.
As to whether the control device will be burnt, this problem needs to confirm the maximum value of this voltage may reach the level and view the relevant parameters of the controller. If you suspect this voltage problem, it is recommended to add an isolation device to the controller side.
It is not recommended to directly connect the DC ground of the control system to the ground of the AC. There is indeed the possibility of damage to the PLC and the module.