What are the measures to prevent the motor from generating shaft current?

Update:26 Oct 2019
Summary:

The measures to prevent the motor from generating shaft […]

The measures to prevent the motor from generating shaft current are:

  1. Install a grounding carbon brush on the shaft end to make the grounding carbon brush reliably ground, and make reliable contact with the rotating shaft to ensure that the potential of the rotating shaft is zero potential, and the static electric charge on the motor shaft is led to the earth at any time, thereby eliminating the shaft current.

  2. In order to prevent shaft current from being generated due to magnetic imbalance, an insulating spacer is added to the bearing housing and the bearing bracket at the non-shaft end to cut off the circuit of the shaft current.

3. The maintenance personnel are required to carefully inspect and strengthen the insulation of the wires or gaskets.

4. In addition to a bearing housing in the base, the remaining bearing housings and metal parts including all the instrument housings mounted thereon are insulated from the ground. Non-insulated bearings should be equipped with grounding brushes to prevent electrostatic charging.

5. For the shaft voltage generated by the cross-linking magnetic flux of the shaft, an insulating pad can be added under the bearing seat on the motor side to cut the circuit formed between the shaft and the bearing bush, so that the shaft current cannot be generated. However, in the actual work, the role of the insulating mat is unclear. From the method of installing the insulating mat and the connection between the bearing seat and the oil pipeline, problems have occurred to some extent, and finally the insulating mat is not insulated, and then formed. Axis current. Therefore, we should always check the insulation strength of the bearing housing and measure it with a 500V shaker. The insulation should not be lower than 0.5MΩ.

6. Keep the purity of the insulating medium oil between the shaft and the bearing bush. It is found that the water in the oil must be filtered. Otherwise, the insulation strength of the oil film can not meet the requirements and it is easy to be broken by low voltage.