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  1. macmckim

    Locked Rotor Time (Tre Vs Te)

    Waross 1964 - T-Frames were introduced (same frame sizes today) 1954 - 1963 there were "U-Frame" - heavy duty, cool running, built like tank Pre 1954, just called Pre-U-Frame motors - frame sizes were different from each motor mfg. Mac
  2. macmckim

    600 VAC Toshiba 2 speed motor won't start

    Gerrybhoy You are showing a 575V power motor (making it a 60HZ unit) - but your noted speeds of 3330 / 1250 RPM does not work for a 60HZ motor. What voltage & frequency are you applying?
  3. macmckim

    space heaters visibly glowing with normal current - is it normal / acceptable?

    ElectricPete Have you measure the skin temperature of purple picture strip heaters - using a thermal gun and compared it to one of the other 7 units? Depending on length of heater (500W) - skin temp can be up to around 200C Mac
  4. macmckim

    dv/dt filters or sinus filters for motor with cable length of 60 meters/200 ft?

    Hello Muthu I'm in Canada and see many 575V applications. Your motor winding pictures that shows the motor frame - the motor frame look like a water cooled unit. I have had a number of customers using Siemens 575V VFD's that have killed motors- factory and EASA repaired units. Your client...
  5. macmckim

    Formula for determining the output power in a electric motor shaf

    Shaft diameter & length is based upon the NEMA Frame size in question, 143T ~ 449T. There's no formula for shaft length. The only formula I am aware of is determining shaft height. Divide by 4 the first two digits of frame size. Mac
  6. macmckim

    10P-1000HP - Shaft Hunting

    Muthu, Tmoose & Gr9blu thankyou for comments and questions. The motor is driving a VRU (Vapor Recovery Unit) Ring Compressor in a refinery. The refinery staff / team has large number of electrical, mechanical and reliability engineer. They know how to set up motor's alignment / magnetic...
  7. macmckim

    10P-1000HP - Shaft Hunting

    Hello Pete Per client the coupling is a "flexible coupling". Yes the motor has BN prox. probes. Probes do not show any abnormal vibration, ever shaft movement. Client's comments: Motor #1 has total running hours around 15000, other two motor #2 & #3 have running hours around 19000. Below...
  8. macmckim

    10P-1000HP - Shaft Hunting

    John; The motor shaft does have a magnetic center groove in shaft. I cannot say what the black line in the video is. Yes the magnetic center is known - and when uncoupled the motor shaft is in correct magnetic center position during no load operation. Mac
  9. macmckim

    10P-1000HP - Shaft Hunting

    itsmoked: Yes only the motor shaft / coupling is moving - the compressor shaft/coupling is not moving. EdStainless: Yes, below the 660 RPM and slower, the shaft/coupling is not moving back and forth.
  10. macmckim

    10P-1000HP - Shaft Hunting

    Good Day Have issue with a 1000HP, 10P (713 RPM) 4kv / 60HZ, TEAAC compressor motor - VFD powered - Variable torque application. Motor is direct coupled (flexible coupling) to VRU ring compressor and is VFD power from 660 - 740 RPM (fully loaded) The motor shaft starts hunting - movement...
  11. macmckim

    evaluate core test thermography results

    Pete; A 1970 vintage Siemens Allis (Allis Chalmers) motor laminations, may not be a C5 core plate material, I am thinking it may have C3 core plate. Going from memory, C3 lamination material require a lower burn out temperature (around 500F), otherwise damage may occur to the organic...
  12. macmckim

    Bearing Insulation Protection

    Hi smrodriguez4 An Louis Allis 1375 HP, Armor Series - it will be more than 20+ years old. Louis Allis Milwaukee Co went of of business about 1998 or so, great products, high quality, rotor designs ahead of their time. I have some old catalogues in my paper files. As noted by ElectricPete...
  13. macmckim

    Bearing Insulation Protection

    smrodriguez4 There are number of factors why your 1375HP does not have any sleeve bearing insulation - age of motor, if over 10 years old, was not important at that time - if motor is operated from utility power, would not be required, unless your company has requirement in company...
  14. macmckim

    Fire pumps shaft shear

    Jimmy Can you advise details on the 150KW motor - IE frame size, speed, enclosure. Nameplate data would help. It appears the motor shaft is breaking in the pump impeller. Are the pumps/motor package integral with each other (flanged motor mounted onto pump) IE: what is called a...
  15. macmckim

    Decaying Motor Voltage

    Zeroseq - The motors are SCIM , induction motors. thanks for the comments. Even though SCIM are 3600RPM (low LRT, IE 60 to 70%), concern is if motors re-energize at a different phase angle, that the motor may go into breakdown torque (BDT of 200%) and cause some...
  16. macmckim

    Decaying Motor Voltage

    Does anyone have a good read on the subject of when we have a Main Bus A -Tie-Main Bus B system where one of the main “B” transformer failed and need to close my tie breaker to avoid all the motors shutdown on bus “B”. Is there a time cycle where I can catch motor before I will do damage to...
  17. macmckim

    filter cover over TEFC shroud... what the...?

    I remember seeing something similar many years ago, filter covers were used on TEFC motors used in the cloth manufacturing plants in North/South Carolina areas. Kept the flying threads,cloth dusts etc from plugging up the fan guard cover, cooling fan fouling etc.
  18. macmckim

    Overspeed with a VFD

    MKMason Based upon your comments: You have a 500HP, 4kV induction motor driving a slurry pump. Going to assume motor is a 1780RPM (4pole mtr) to a gearbox and then to the pump. You want to drive the motor from the 50% to 125%. (885 to 2225 RPM) Typically slurry pumps (centrifugal type)...
  19. macmckim

    bearing damage of 3500kw motor

    Based on the bearing damage, the bearing was skidding in the raceway and then became jammed, causing the extensive damage /wear patterns on the rollers. I beleive there was some contamination / materials in the end-bracket's grease tube. Possible the repair shop did not clean the grease tube...
  20. macmckim

    Electric Motor Bearing Heaters

    Bearing heaters are not installed in anti-friction bearings motors. The heaters are installed on self lubricated or forced lubricated sleeve bearing motors - called oil sump heaters. Typically around 10 to 20 watt immersion type heater in stalled in bottom of sleeve bearing bracket (oil sump)...

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