how to prevent electrical erosion in bearings pumps

Bearing Handbook for Electric Motors

11 Find the cause of bearing failures Bearings are built to last so frequent failures may point to an installation or lubrication problem QIBR bearing analysis experts can identify the cause of bearing failure and help you prevent it in the future 12 The contact between the bearing ring and a

Bearing Protection

During virtually every VFD switching cycle induced shaft voltage discharges from the motor shaft to the frame via the bearings leaving a small fusion crater (fret) in the bearing race When this event happens temperatures are hot enough to melt bearing steel and severely damage the bearing lubrication

ABB drives

Apr 27 2011This is known as electrical discharge machining or EDM The effect of a single pulse is insignificant but a tiny EDM pit is an incontinuity that will collect more pulses and expand into a typi-cal EDM crater The switching frequency of modern AC drives is very high and the vast number of pulses causes the erosion to quickly accumulate

Electrical pitting

To prevent electrical erosion of bearings and other issues generator manufacturers incorporate a slip ring and brush system to provide a low resistance path to ground for any charge that may build on the rotor shaft This grounding system may degrade over time if the ground ring becomes oxidized the brushes become worn or the brush holder

How to Control Erosion (with Pictures)

Jan 18 2020A channel is a spot where running water cuts into the soil and forms a rut By filling the channel with compost or manure you will help prevent further erosion If a channel increases in size with each rain it can eventually form a gully which is harder to address Stop a channel before it turns into a gully by using a hoe to break it up

Preventing VFD/AC Drive Induced Electrical Damage to AC

As demonstrated above electrical damage to VFD/ac motor bearings begins at startup and grows progressively worse As a result of this damage the bearings eventually fail To prevent such damage in the first place the induced shaft current must be diverted from the bearings by insulation and/or an alternate path to ground

The use of protective coatings on pump components

Pump shaft bearing journals Pump shafts often incorporate oil or product lubricated bearing surfaces that are integral to the shaft or are in the form of a shaft sleeve These bearing surfaces are often subject to an unexpected amount of wear even in the presence of 'clean' oil or process medium

Preventive maintenance checklist for centrifugal pumps

Jul 17 2017For pumps equipped with re-greaseable bearings avoid mixing greases of differing consistencies or types Also note that the shields must be located toward the interior of the bearing frame When re-greasing confirm that the bearing fittings are absolutely clean to prevent contamination which can decrease bearing life

12 Reasons Why Bearings Fail

Prevent electrical currents from flowing through the bearing by grounding or using insulated bearings 8 Fatigue (Spalling) Spalling is often the result of overloading an excessive preload tight inner-ring fits and using the bearing beyond its calculated fatigue life What to Look for

Understanding Journal Bearings

Bearings are used to prevent friction between parts during relative movement In machinery they fall into two primary categories: anti-friction or rolling element bearings and hydrodynamic journal bearings The primary function of a bearing is to carry load between a rotor and the case with as little wear as possible

How to Determine Root Cause of Excessive Pump Vibration

Pumps with high suction energy and low NPSH margins especially when operated in the suction recirculation flow range (see June 2010 column) may experience noise vibration and/or minor cavitation erosion damage with impeller materials that have low cavitation resistance such as cast iron or

Protecting Thrust Bearings in Deepwell Submersible Pumps

Apr 17 2013Most deepwell submersible pumps use fluid film thrust bearings instead of ball and roller bearings used in most surface mounted pumps The unique thing about this type of bearing is that there are no moving parts within the bearing so if the motor is

Bearing Protection

During virtually every VFD switching cycle induced shaft voltage discharges from the motor shaft to the frame via the bearings leaving a small fusion crater (fret) in the bearing race When this event happens temperatures are hot enough to melt bearing steel and severely damage the bearing lubrication

Preventing Damage to Motor Bearings

As demonstrated previously electrical damage to VFD/AC-motor bearings begins at startup and grows progressively worse As a result of this damage the bearings eventually fail To prevent such damage in the first place the induced shaft current must be diverted from the bearings by insulation and/or an alternate path to ground Insulation

How To Find And Prevent Pitting Crevice Corrosion

Mar 12 2013These lower-profile corrosion types are dangerous and deserve your attention By Gerald O 'Jerry' Davis P E Davis Materials Mechanical Engineering Inc Pitting and its closely related form crevice corrosion cause significant problems across industry yet don't receive the attention they deserve Maintenance professionals often focus on other types of corrosion such as stress

Understanding Bearing Housing Protection and Reliable

An increasing gas temperature (usually air or an air-oil mixture) in the bearing housing (A in Fig 2) tends to elevate pressure in the bearing housing This elevated pressure drives down the oil level in the housing (arrows in Fig 2) increases the oil level in the narrow annular space above the tip of the wing nut and can result in

How to Determine Root Cause of Excessive Pump Vibration

Pumps with high suction energy and low NPSH margins especially when operated in the suction recirculation flow range (see June 2010 column) may experience noise vibration and/or minor cavitation erosion damage with impeller materials that have low cavitation resistance such as cast iron or

Demagnetizing motor shafts to prevent bearing failures

The most likely culprit is electric current through the motor and shaft either from internal dissymmetry welding or from a variable frequency drive It can also be caused by electrical faults in the system or even a lightning strike We of course know that shaft voltages and the associated currents can cause bearings

3 Ways to Prevent Metals from Corroding

Mar 26 2020How to Prevent Metals from Corroding Corrosion is a natural process that happens to all metals but it can be slowed down greatly with a few different treatments It is caused by the presence of oxidizing agents in the environment like

How to Determine Root Cause of Excessive Pump Vibration

Pumps with high suction energy and low NPSH margins especially when operated in the suction recirculation flow range (see June 2010 column) may experience noise vibration and/or minor cavitation erosion damage with impeller materials that have low cavitation resistance such as cast iron or

Protection against Wave

Protection against Wavebased Erosion The guidelines below address the elements of shore structure design common to nearly all erosion control structures subject to direct wave action and run-up 1 Minimize the extent waterward Erosion control structures should be designed with the smallest waterward footprint possible

How to prevent false brinelling in rolling

Jan 20 2015The average motion within each bearing is non-zero promoting movement of the lubricant within the rolling elements One caveat: This design doesn't resolve issues from assemblies that lie motionless for substantial periods of time between uses — on spare electric motors for example This needs oscillatory motion of a magnitude large

Preventing VFD/AC Drive Induced Electrical Damage to AC

As demonstrated above electrical damage to VFD/ac motor bearings begins at startup and grows progressively worse As a result of this damage the bearings eventually fail To prevent such damage in the first place the induced shaft current must be diverted from the bearings by insulation and/or an alternate path to ground

Preventive maintenance checklist for centrifugal pumps

Jul 17 2017For pumps equipped with re-greaseable bearings avoid mixing greases of differing consistencies or types Also note that the shields must be located toward the interior of the bearing frame When re-greasing confirm that the bearing fittings are absolutely clean to prevent contamination which can decrease bearing life

Electrical discharge machining

Electrical discharge machining (EDM) also known as spark machining spark eroding die sinking wire burning or wire erosion is a metal fabrication process whereby a desired shape is obtained by using electrical discharges (sparks) Material is removed from the work piece by a series of rapidly recurring current discharges between two electrodes separated by a dielectric liquid and subject

White Paper: Detection of electrical discharges in bearings

Finally electrical erosion can cause lubricant decomposition and degradation Blackened grease is a common sign of advanced electrical erosion as high temperature peaks locally cause the thickener base oil and additives to react See figure 9 Figure 5: micro crater of a few um in diameter Figure 7: Fluting on the outer ring raceway of a bearing

Lubricating And Troubleshooting Centrifugal Pumps

Jun 01 2012There are two types of oil-mist: pure and purge Pure mist is applicable to ball bearings in pumps and electric motors Purge mist is suited to any type of bearing As with motors oil-mist lubrication of pumps offers a number of benefits: Bearings running significantly cooler (15-30 degrees F) Clean once-through lubrication