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Recent content by magneticted

  1. magneticted

    Shaft currents, insulating pipework flanges

    If we have a large MV motor fixed speed with forced lubricated sleeve bearings and the motor manufature is offering insulated bearings DE & NDE ( with DE earth cable )Does the oil inlet & outlet pipework which has ANSI / DIN flanges, do these flanges have to be insulated. And if so how are are...
  2. magneticted

    Siemens HV motors

    Regarding Siemens HV motors does anyone know the meaning of of "Torque class KL4 KL5, KL16", which have appeared on some data torque curves. Do you think this could mean type of rotor construction, double cage etc
  3. magneticted

    Ex accessories

    With a Zone 2 motor where we have several accessories, for example Exe stator and Exe bearing RTD's wired to a EExe II auxiliary terminal box as standard, would it be possible to have the RTd's wired to a Exd auxiliary box
  4. magneticted

    Sizing unit transformer

    Looking at a 6 Mw 11 Kv synchronous machine efffy 97% PF to be 0.9 leading to 0.9 lagging for continous operation,and require a 33kV / 11 kV power transformer. KVA rating of transformer, would this be based on KVA rating of motor
  5. magneticted

    TEAAC Motors

    Air to air cooled motor with air heat exchanger whereas the cooler tubes are manufactured from a Aluminium alloy AI MgSi would this materiall be suitable for offshore use
  6. magneticted

    Soft Starter current limit

    Hi Mark Thanks for your help, not sure I'm clever enough to do what you suggested. Attached is the motor current / torque curve. It shows 590% flc the motor not made yet, and the 590% could be subject to a manufacturing tolerance of 10% hence 650% ( worst case )The client is going to limit the...
  7. magneticted

    Soft Starter current limit

    Hi Guys. Just trying to understand soft starter principles. If we want to soft start a 3Mw motor 6Kv with 60% starting torque, and 650% current, compressor drive.and we limit the starting current to 400%, what happens to the voltage, how do we calculate the corresponding voltage at this point...
  8. magneticted

    Water Cooled Machine IC81W

    Thanks, however the kilowatt loss seems high. If this was a air to air cooled machine, then the heat loss as estimation we would say kw / effy = 43.84 kw (1043.84 - 1000 ) What we are trying to establish is the heat loss of this water cooled machine into the pump room. The water circuit will...
  9. magneticted

    Water Cooled Machine IC81W

    Hi guys can anyone please give a estimation or rule of thumb for determining the heat loss fron a water cooled motor ( Heat Exchanger )For example we hae a 1Mw 4p motor with efficiency at FL of 95.8%, Water inlet is 33 Deg C , and oulet approx 39 Deg C, Water flow rate is 9.4 m3/h
  10. magneticted

    Re rating a Synchronous Machine

    We have a 9MW 4P 6.6Kv 60hZ Synchronous Motor, and we are thinking of using this on another plant where the frequency is 50 hZ. We know we will have to rate the motor for a lower power, but is this feasable. What are the issues we have to think about
  11. magneticted

    5 MVA Generator

    Customer has a 5MVA Generator operating in island mode, and the question is what would be the biggest motor we could connect to this GEN considering a typical IEC 6Kv motor with starting current ratio of 6.5 times flc.Efficiency 95% and power factor 0.90, and a starting voltage of 80%
  12. magneticted

    Volt Drop Calculation with Auto transformer

    Calculating volt drop at say 6Kv bus, with 126MVA, and a motor rating of 7.7Mw 6Kv FLC 832A and starting current of 4401 a ( Is/In 5,29) and volt drop on 6kV net not to exceed 15% then on DOL we get 27% drop. So if we introduce a auto transformer with a rating of 9MVA, impedance of 6% and say...
  13. magneticted

    NEC500 / NEC505

    From the point of view of electric motors whereas UL are moving to harmonizing the US zone requirements etc.Are class 1 division 1, and class 1 division 2 still applicable, or is now the correct thing to do to offer class 1 zone 1 or class i zone as the case maybe. Or are the two concepts...
  14. magneticted

    Vibration

    It is a 4 pole motor 50 hz 1500 rpm
  15. magneticted

    Vibration

    Can one of you kind gents help me out here. We have specification from a client stating "" that the vibration of the motor shall not exceed 0.5 mil double amplitude in any direction at full or no load "". The motor in question is a IEC 400 frame with sleeve bearings. The motor spec states...

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