Why motor NDE bearing is insulated?

Insulating one bearing will stop this circulation. The purpose of insulated bearing for Motors with VFD drives or the Alternators is to prevent the flow of circulating current in a closed circuit through bearing and ground (if bearing is not insulated) and consequently prevent the bearing from damage.

What is the difference between DE and NDE bearing?

In the basic bearing system, the floating bearing is situated at the drive end (DE) and the located bearing (axially located from Type of construction 160 and above) is situated at the non-drive end (NDE).

Why do we insulate bearings?

Insulated bearings prevent premature bearing failures eventually caused by stray electrical currents. Due to the relatively good metal-to-metal electrical contact, only very high amperage currents such as welding currents are able to destroy the raceway surface.

What is pulse width modulation in VFD?

The process involved in inverting the DC voltage to the variable voltage variable frequency (VVVF) AC voltage in the inverter section of the VFD is called pulse width modulation or PWM. The goal of the PWM control is to create a sine wave current waveform output to produce torque in the motor.

What is an insulated bearing?

Insulated bearings prevent premature bearing failures eventually caused by stray electrical currents. Insulation properties must remain stable regardless of environmental conditions, in particular when bearings are stored, handled and operated in humid climates.

What is DE and NDE side of motor?

Topology of the rotor cage (DE = drive end, NDE = non drive end)

How do you check an insulated bearing?

The insulation on both sides of the metal plate can be checked separately by connecting the ohmmeter between terminals A and G, and between A and B. The thrust-bearing insulation resistance should measure from about 10,000 ohms to infinity.

Is pulse width modulation AC or dc?

Pulse width modulation uses transistors which switch the DC voltage on and off in a defined sequence to produce the AC output voltage and frequency. Most VFD’s today utilize insulated gate bipolar transistors or IGBT’s.