What is fluting in electrical?

Electrical fluting occurs when a current is passed through the motor bearing instead of a grounded source. PWM (Pulse Width Modulated) drive switching frequencies result in undesirable motor shaft currents, a side effect that causes bearing damage within the motor through pitting and fluting.

How does fluting occur?

What is Fluting? Fluting is a form of electrical damage suffered by electric motor bearings when alternating (AC) or direct (DC) current actually passes through the metal bearing. As the currents pass through the bearings, they can leave behind surface damage that results in premature bearing failure.

What causes fluting in bearings?

Fluting is the result of shaft currents in an electrical motor going to ground through the motor bearings. This problem is most often found with drive systems, however, welding operations in the area can cause this if the motor shaft becomes part of the ground path.

How do you stop bearing fluting?

Whenever possible, the best option for preventing bearing fluting is installing grounding rings on the shaft. For example, brush-based grounding rings can easily capture and reroute electrical buildup before it reaches sensitive components.

What is frosting in bearing?

▪By definition, “Bearing Frosting” is term used to describe a. physical defect to a bearing surface caused stray. electrical currents. ▪It is similar in nature to “EDM” (Electrical Discharge. Machining) whereby bearing surfaces vaporize or soften.

What is pitting in bearings?

Electrical discharge through the oil film between the shaft and bearing in electrical machinery or in fans and turbines may occur due to faulty insulation or grounding, or due to the build-up of static electricity.

What causes Brinelling?

True brinelling is caused by shock or excessive loads due to improper mounting, dropping of machinery during handling, excessive static or impact loads during the operating cycle.

Why do motor bearings fail?

According to a recent study, up to 80 percent of bearing failures are caused by improper lubrication. This includes insufficient lubrication, use of improper lubricants or excessive temperatures that degrade the lubricant.

What is a dV dT filter?

A dV/dT filter is a device that controls the voltage spikes generated by adjustable frequency drives (AFDs) and long motor lead lengths. This voltage spike event is generally known as the reflected wave phenomenon [1].

What is the most common cause of bearing failure?

While it may seem like common sense, standard wear and tear is one of the leading causes of bearing failure. Eventually all bearings fail due to wear, however, excessive load, vibration or force can cause a bearing to wear out long before it should. Most of this excess force is caused by improper installation.

What is insulated bearing?

Insulated bearing for motor is used to prevent the circulating current through the motor bearing. The circulating bearing current can damage the bearing. When we run induction motor by variable frequency drive, it is apt to fail caused by bearing failure.

Can a VFD damage a motor?

2) VFDs can destroy motor bearings.

These arcs destructively cause pitting, frosting and fluting in motor bearings and bearing races, resulting in premature motor failure.

What is a VFD filter?

VFD output filters begin with a reactor and are built out with additional resistive and capacitive components, forming a low pass filter. They are designed to limit the peak voltage to 1,000 volts. These filters are typically applied to applications lead lengths are up to about 1,000 feet.

What is harmonic filter?

Harmonic filters are series or parallel resonant circuits designed to shunt or block harmonic currents. They reduce the harmonic currents flowing in the power system from the source and thereby reduce the harmonic voltage distortion in the system.

What is a sinus filter?

Sinus filters, as the name suggests, are used to convert the output voltage of the frequency converter into a sinusoidal voltage. Frequency converters generate high electrical interference signals on the motor cable, which not only disturb the load, but also increase the insulation load on the motor.

What happens if bearing fails?

The consequences of bearing failure are far-reaching for your facility. These can include increased downtime, high-maintenance costs, missed deliveries, loss of revenue and, in some extreme cases, may injure workers. When a bearing fails, it negatively impacts your facility, your reputation and your bottom line.

What is the remedy for damaged motor bearing?

Oil lubrication should be considered where speeds and temperatures are high. If the motor bearing is damaged, we need to replace it.

What is the most common cause of motor failure?

Winding insulation breakdown and bearing wear are the two most common causes of motor failure, but those conditions arise for many different reasons.
...
Shaft imbalance

• Dirt accumulation.
• Missing balance weights.
• Manufacturing variations.
• Uneven mass in motor windings and other wear-related factors.

What is bearing fretting?

A type of frictional corrosion, fretting is caused by microscopic oscillating motions (vibrations) between the bearing surfaces. Fretting is a subtype of the “Corrosion” mode of damage/failure, and is often referred to as “fretting corrosion” because it produces fine, metallic particles that can oxidize, like rust.

What is bearing damage?

The spalling damage is typically from nicks, dents, debris, etching and hard-particle contamination in the bearing. It's the most common type of spalling damage, and often appears as arrowhead-shaped spalls, propagating in the direction of rotation.

What is preload bearing?

What is Bearing Preload? Bearing Preload is the process of adding a sustained axial load, independent of external loads, to a bearing. An axial preload ensures constant contact between the ball complement and bearing races reducing or eliminating both modes of play.

What is electrical pitting?

Electrical discharges in bearings may occur in shaft lines equipped with electrical machines. This effect, known as electrical pitting, consists of the removal of material from the pad surface; this can lead to bearing pad failure mainly because of overheating and reduced load capacity.

What is pitting wear?

Pitting wear is due to surface failure of a material as a result of stresses that exceed the endurance (fatigue) limit of the material. Metal fatigue is demonstrated by bending a piece of metal wire, such as a paper clip, back and forth until it breaks.

What is reactor filter?

Filter reactors protect reactive power compensation equipment from overload caused by excessive harmonic levels in medium and low voltage distribution systems. They are also used in a variety of configurations of harmonic filters to remove unwanted harmonics from electric power systems.

Why chokes are used in VFD?

To protect thyristor form high transient current, because an inductance does not allow sudden change in current. All the semiconductors are having some tolerance to stand high transient current but beyond the limit which leads to semiconductor failure.