What is insulated bearings motor?

A. Purpose of insulated bearings motor

The so-called electrically insulated bearings are also insulated bearings. Insulated bearings motor includes all rolling bearings that can prevent the passage of current. Whether it is an inner ring or an outer ring with a ceramic coating, it is called an insulated bearing. The ceramic coating prevents the passage of electricity and has insulating capabilities.

The rolling elements of hybrid bearings are made of ceramic and therefore also have insulating properties. It is made of rolling elements to prevent the passage of current.

B.Selection method of insulated bearings motor

In general, it is very difficult to completely eliminate the potential difference inside the bearing. However, if we can stop or greatly reduce the current flow through the bearing, we can prevent the bearing from galvanic corrosion. Various insulated bearings are currently designed for this purpose. Depending on the type of voltage generated, the insulation method of the bearing is selected.

1. Induced voltage generated along the axis

The induced voltage along the shaft creates a current loop through bearing 1, housing and bearing 2 simultaneously. One reason for this kind of shaft voltage is due to the uneven distribution of magnetic flux inside the motor, especially in some motors with a small number of pole pairs. At this point, simply insulating one end of the bearing can completely cut off the current loop. Typically insulated non-drive end bearings.

2. The voltage between the shaft and the bearing seat

If a voltage occurs between the shaft and the housing, the current flows through each bearing in the same direction. This is mainly caused by the common mode voltage brought by the frequency converter. In this case, the bearings at both ends of the motor should be insulated. The determining factor for the selection of insulation is the time characteristic of the current and voltage. If it is DC voltage or low-frequency AC voltage, the insulation effect depends on the pure resistance value of the insulating layer; if it is high-frequency AC voltage (common in equipment using frequency converters), it depends on the capacitive value of the insulating layer.

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