the purpose of insulated bearing for motors with vfd

Preventing VFD/AC Drive Induced Electrical Damage to AC

Most motor bearings are designed to last for 100 000 hours yet motors controlled by VFDs can fail within one month (720 hours) An HVAC contractor recently reported that of the VFD-controlled 30-60 hp vane axial fan motors he installed in a large building project all failed within a year (two within 6 months)

Consulting

Nov 16 2010Ask an engineer the purpose of a variable frequency drive (VFD) and a common answer would be "to save energy " While the motivation to increase energy efficiency could be financial (reduced energy costs) or ethical (reduce greenhouse gas emissions associated with power production) it is taken for granted that VFDs are an easy way to improve energy efficiency in a motor application

A Practical Guide for Using Variable Frequency Drive

on a 100hp VFD) ˜ Multiple motors on a single VFD (Fan Array) ˜ Heavy-duty load filters (e g sine wave filters) ˜ Transformers (or any loads other than motors) When using scalar control one must set up V/F preferably within the motor nameplate range If V/F is: ˜ Too low the motor will have higher slip less – torque and hotter

Motors 101 and Considerations on Variable Speed Systems

insulated bearings to conduct rotor currents around the bearing and prevent rotor currents from finding a better return path through the driven equipment This still assumes the motor frame is the best return path to the drive Can be applied to motors under 125HP without insulating ODE 31

What is The Purpose of a VFD?

The purpose of a VFD is specifically intended to control the speed of an AC motor by strictly observing the above parameters Here the speed of the motor is varied by changing the magnitude of the input voltage as well the frequency at a constant ratio and thus the motor is able to maintain a constant torque even at lower speeds

Reasons of VFD driving motor bearing failures

AEGIS recommends that motors over 100HP use an insulated bearing on the ODE and a grounding ring on the DE Installing two insulated bearings is not advised because the circulating currents in the rotor will have no path to ground (VFD) for an existing electric motor it's important to know the purpose and characteristics of the different

PROVIDING INSULATED BEARING FOR VFD APPLICATION for

Oct 19 2009PROVIDING INSULATED BEARING FOR VFD APPLICATION for NON-DRIVE END OF THE MOTOR The Stator as well as Rotor of motors are made up of Magnetic circuit and the heat produced due to Eddy currents should be reduced The present day motors are of thin Laminations for core as well as for Rotors and reduces the heating effect

What is The Purpose of a VFD?

The purpose of a VFD is specifically intended to control the speed of an AC motor by strictly observing the above parameters Here the speed of the motor is varied by changing the magnitude of the input voltage as well the frequency at a constant ratio and thus the motor is able to maintain a constant torque even at lower speeds

Preventing VFD/AC Drive Induced Electrical Damage to AC

Most motor bearings are designed to last for 100 000 hours yet motors controlled by VFDs can fail within one month (720 hours) An HVAC contractor recently reported that of the VFD-controlled 30-60 hp vane axial fan motors he installed in a large building project all failed within a year (two within 6 months)

TECH TOPICS VFD Best Practices: Getting the Most from Your

an older motor with 1200v insulation this could cause a failure "Inverter Duty" motors are insulated for 1488 v minimum (CIV) as specified by NEMA MG1 part 31 1600 v or higher is better The variables that determine the risk of reflected waves are: • Motor insulation rating particularly its Corona Inception Voltage (CIV) rating

Insulated bearing

Mar 12 2011Hello forum members We are in the process of ordering one 1 200 kW 5 5 kV wound electric motor to drive a rock crusher Is it essential that the non drive bearing should be an insulated one?Though I know that for VFD application insulated bearing on NDE side is compulsory The crusher would not be driven by a VFD

Influence of VFD on motor shaft voltage and bearing currents

The basic reason for bearing currents to occur within a variable frequency drive fed motor is the so called common mode voltage The motor capacitive impedances become low in face of the high frequencies produced within the inverter stage of the variable frequency drive causing current circulation through the path formed by rotor shaft and

PROVIDING INSULATED BEARING FOR VFD APPLICATION for

Oct 19 2009PROVIDING INSULATED BEARING FOR VFD APPLICATION for NON-DRIVE END OF THE MOTOR The Stator as well as Rotor of motors are made up of Magnetic circuit and the heat produced due to Eddy currents should be reduced The present day motors are of thin Laminations for core as well as for Rotors and reduces the heating effect

Insulated Ball Bearings

Coating the outer ring of the bearing provides a barrier (capable of resisting at least 100 Megaohms at 500 VDC) against any stray currents that would pass through the bearing MEGAOHM™ Series bearings are featured as OEM equipment on wind turbine generators traction motors for railway cars and variable speed electric motors in wastewater

SGR Protecting VFD

• Installing a Shaft Grounding Ring (AEGIS SGR or iPRO) on any motor operated on variable frequency drives (VFD) • Isolating a motor bearing with an insulated sleeve coating bearing housing with insulating material adding a hybrid ceramic ball bearing or ceramic coated bearing to the repair for motors over 100 HP (75kW) 4

Electric motor items to consider when adding a VFD to your

The winding must be insulated suitable for inverter duty (or VFD operation) Special insulation is required to protect the motor from inverter type switching frequency voltage spikes The use of a proper wire strand and turn insulation protects the motor (such as inverter duty wire designed with a specially formulated film insulation for this

Influence of VFD on motor shaft voltage and bearing currents

The basic reason for bearing currents to occur within a variable frequency drive fed motor is the so called common mode voltage The motor capacitive impedances become low in face of the high frequencies produced within the inverter stage of the variable frequency drive causing current circulation through the path formed by rotor shaft and

VFD's and bearing Fluting

Aug 11 2017Many VFD-ready motors have bearings insulated from the case to prevent that current 4) conductive grease for the bearings 08-11-2017 12:03 PM #17 Monarchist View Profile View Forum Posts Banned Join Date Oct 2012 Country UNITED STATES State/Province ia Posts 10 264 Post Thanks / Like Likes (Given)

AEGIS SHAFT GROUNDING RING Best Practices for Bearing

motor's bearings Ref: NEMA MG1 Part 31 4 4 3 There are two primary sources of bearing currents in VFD driven AC motors (Bearing Currents A and B): Bearing Current s 11 00 200 300 Motor Horse Power Total Qualitative Bearing Currents Region 1 Motors up to 100 HP/75kW Region 2 Motors over 100 HP/75kW About VFD Induced Shaft Voltages and Bearing

Insulated bearings for electric machines

A: The bearings in induction motors can benefit from insulated bearings where shaft currents are high and use the bearings as a route to earth This I am sure you are aware Most induction motors do not suffer with this problem however those fed with variable frequency drives can and do If you feel that your application would benefit from

Reasons of VFD driving motor bearing failures

AEGIS recommends that motors over 100HP use an insulated bearing on the ODE and a grounding ring on the DE Installing two insulated bearings is not advised because the circulating currents in the rotor will have no path to ground (VFD) for an existing electric motor it's important to know the purpose and characteristics of the different

VFD

If you're not seeing obvious ESD damage the bearing life problem is likely not directly variable frequency drive (VFD) related especially if some of the bearings are insulated It has been my experience that whatever the most complicated piece of equipment in the system that's what gets blamed and VFD falls into that category

Influence of VFD on motor shaft voltage and bearing currents

The basic reason for bearing currents to occur within a variable frequency drive fed motor is the so called common mode voltage The motor capacitive impedances become low in face of the high frequencies produced within the inverter stage of the variable frequency drive causing current circulation through the path formed by rotor shaft and

What is The Purpose of a VFD?

The purpose of a VFD is specifically intended to control the speed of an AC motor by strictly observing the above parameters Here the speed of the motor is varied by changing the magnitude of the input voltage as well the frequency at a constant ratio and thus the motor is able to maintain a constant torque even at lower speeds