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jOmega

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  1. Additional considerations: For Safety Reason......Each leg should be fused with fast acting fuses. For Safety Reason..... Light bulbs should be enclosed by a wire mesh screen. Bulbs can and will explode when least expected. Use 300-watt bulbs as Mark stated. If you use bulbs of lower wattage, you may not draw sufficient current to satisfy the Ih (Holding Current parameter) of the SCR's, and they will turn-off. Strip heater elements could be used instead of light bulbs. Just be sure that they are rated correctly for voltage and minimum wattage required. Kind regards,
  2. Caveat Emptor, y'all.
  3. For our discussion, the following conditions. The first conveyor to receive the head end of the bar we shall call Conveyor #1 The next conveyor in line shall be called Conveyor #2 and the last conveyor to recieve the head end of the bar we shall call Conveyor #3 As you said, each conveyor has its own VFD .... So which VFD trips first ...... #1 ? #2 ? or #3 ? Does only ONE of the VFDs trip or more than one ? If more than one ..... which trips first ...... second ...... third ?
  4. Yes You have made an incorrect assumption; " ...that the torque remains the same at the driven wheel." To obtain the same linear speed at the wheel, the Gear Ratio would have to DECREASE ...... The motor would have to supply more torque into the gear box to make up for the loss of torque delivered to the wheel by the reduction of the gear ratio. If you increase the torque rating of the motor, the motor will need more iron to support the higher torque value. To put more iron into the motor, the size of the motor must increase.
  5. The key parameter to observe is the DC Bus Voltage. the OV trip is caused by the DC Bus Voltage exceeding the preset limit. Cause: either the AC line voltage is going too high .... could be caused by spike transients on the AC line.... OR the mechanical load is causing the motor to overspeed and regenerate energy back onto the DC Bus. Question for you: ------ What is happening just before and at the time the OV trip occurs ? Another question for you: ------- Tell us about the orientation of the conveyor .... is it horizontal ? is it inclined downward ? And what is the load that is being placed on the conveyor .... please describe .
  6. Hi G^2 working on reply for you. Q. dc motor - Series or Shunt wound ? Speed/Torque Spec ? Assume drum is driven at stated drum shaft .... correct ? and is direct coupled to output shaft of gearbox ... correct. Assume motor is direct connected to input shaft of Gearbox ... correct ? Kind regards,
  7. Srinath, I would believe that the reason you have not had any replies to your posting is ...... because no one knows what you are talking about. You have used terms that while they may be familiar to you.... are not universal in scope. For example, DG supply ..... I have no idea what a DG supply is. EB supply ? .... I have no idea what an EB supply is. Capacitor + Reactor ..... those are the individual names of electrical components. But you do not describe how they are configure.....or how they are connected, and to what. Take a few moments and consider that we cannot see what you are talking about and so, you must be very descriptive in your statements so that we can have a chance at picturing what it is your are involved with. Be as complete as you can in supplying detail for us to understand. Kind regards,
  8. To those students whose senior project involves either IPMSM / PMSM motor design or Drive System design, see the below link that is found in the Library sub-section of the Motor Control section of this forum. http://www.lmpforum.com/inforum/Ipmsm-Pmsm-t4316.html
  9. Hi Mark, A bit of browsing on SEL's (Schweitzer Engineering Labratories) re-designed website led us to the below link which I assume is the Analysis paper that went M.I.A. (Missing In Action)..... Induction Motors: Part I - Analysis Author: S. E. Zocholl Kind regards,
  10. Pens92 Before sizing the motor.... some things must be made known; not the least of which is "What is Alpha: What does it represent" Remember, we all aren't privy to what you've been looking at. Also, there are some questions that must be asked and answered before getting to an answer (result) .. Load Inertia: Direct Driven or geared to motorIf geared, geared up or geared down ?What is the gear ratio ? (from motor to driven load)What is Inertia of driven load ? (and in what unit of measure is it stated ?)what is minimum speed -of driven load - (speed at which acceleration begins) ?What is final speed - of driven load - (speed at which acceleration ends) ? How do min & max load speed correlate to motor speed - i.e., min load speed = what motor speed and what max load speed = what max motor speed..... How much time is required to accelerate the driven load from minimum speed to maximum speed ?From this information, the minimum HP (kW) of the motor can be calculated. I say minimum because you also need to take into account the Duty Cycle HP ..i.e., how often between acceleration / deceleration events ... and how long will it run at constant speed..... Duty Cycle can add heat to the motor which may require increasing the Power Rating of the motor to accommodate the additional heat. Ok.. that should give you a header in the right direction .... and while you're gathering the answers to the above questions, take a look at ... see: Constant Torque Acceleration Time of Fan Some years back, I did a presentation on Torque - Acceleration - Time for a fan. The analysis and graph are presented in the above link and therein you will see the relationship between inertia - torque -speed - time ... I think you will find that it will be appropriate to your inquiry. Look forward to further discussion on this with you. Kind Regards...
  11. jOmega

    Ipmsm / Pmsm

    In doing some research on this topic, I came upon these two papers which I expect will be of benefit to those who are looking for an education on IPMSM/PMSM motors ... and a drive system relevant thereto. These papers are in PDF file format and are the Doctoral Thesis and Master Thesis respectively submitted by their authors. ---------------------------------------------------------------------------------------- 12-2009 Development and Analysis of Interior Permanent Magnet Synchronous Motor with Field Excitation Structure by Seong Taek Lee University of Tennessee - Knoxville, USA Link: http://trace.tennessee.edu/cgi/viewcontent...magnet+motor%22 "ABSTRACT Throughout the years Hybrid Electric Vehicles (HEV) require an electric motor which has high power density, high efficiency, and wide constant power operating region as well as low manufacturing cost. For these purposes, a new Interior Permanent Magnet Synchronous Motor (IPMSM) with brushless field excitation (BFE) is designed and analyzed. This unique BFE structure is devised to control the amount of the air-gap flux for the purpose of achieving higher torque by increasing the air-gap flux at low speed and wider operating speed range by weakening the flux at high speed. On the process of developing the new IPMSM, the following analysis results are presented. Firstly, a new analytical method of output torque calculations for IPMSM is shown. This method works well when using a 2-dimensional magnetic equivalent circuit of a machine by omitting the step of calculating the inductance values which are required for the calculation of the reluctance torque. Secondly, there is a research about the slanted air-gap shape. This structure is intended to maximize the ratio of the back-emf of a machine that is controllable by BFE as well as increase the output torque. The study of various slanted air-gap shapes suggests a new method to increase torque density of IPMSM. Lastly, the conventional two-axis IPMSM model is modified to include the cross saturation effect by adding the cross-coupled inductance terms for calculating the power factor and output torque in comparing different saturated conditions. The results suggest that the effect of cross-coupled inductance is increase when d-axis current is high on the negative direction." ------------------------------------------------------------------------------------------------------- 2006 MODELING AND SIMULATION OF PERMANENT MAGNET SYNCHRONOUS MOTOR DRIVE SYSTEM by Enrique L. Carrillo Arroyo UNIVERSITY OF PUERTO RICO MAYAGÜEZ CAMPUSLink: http://citeseerx.ist.psu.edu/viewdoc/downl...p1&type=pdf "ABSTRACT The thesis deals with the detailed modeling of a permanent magnet synchronous motor drive system in Simulink. Field oriented control is used for the operation of the drive. The simulation includes all realistic components of the system. This enables the calculation of currents and voltages in different parts of the inverter and motor under transient and steady conditions. The losses in different parts are calculated, facilitating the design of the inverter. A closed loop control system with a Proportional Integral (PI) controller in the speed loop has been designed to operate in constant torque and flux weakening regions. Implementation has been done in Simulink. A comparative study of hysteresis and Pulse Width Modulation (PWM) control schemes associated with current controllers has been made in terms of harmonic spectrum and total harmonic distortion. Simulation results are given for two speeds of operation, one below rated and another above rated speed."
  12. Hi Mark, I was browsing thru tonite and came upon this old chestnut from almost 5 years ago ... The first thing that came to mind is: Where's the System Curve ? The second thing that came to mind is: Is this an open or closed loop system? The third thing that came to mind is: Where is the pressure transducer located; at the discharge of the pump? or at some place further downstream where a controlled pressure is required .... and if so ...how far from pump discharge is that location ? There are other items to consider, but these will do for now to see if there's any interest in revisiting this bone from the past. Kind regards,
  13. See: Student Postings The Students section of this Forum is the correct place for posting your inquiry. Kind regards
  14. see: http://cache.freescale.com/files/microcont...nual/DRM110.pdf http://people.virginia.edu/~bjb7f/Old%20St...0PM%20drive.pdf
  15. Hello Kashif: I have spent this day doing some research on the internet for you. Below are links to reference material that I think will be helpful to you. Good luck with your project. -------------------------------------------------------- PowerBox: The Safe AC Power Meter http://courses.cit.cornell.edu/ee476/Final...xg37/index.html Power Box C# Source Code Zip file http://courses.cit.cornell.edu/ee476/Final...xg37/Source.zip Active power meter data sheet and Application Note, Data Sheet, Circuit, PDF, Pinout | Datasheet Archive http://www.datasheetarchive.com/active%20p...-datasheet.html AVR465: Single-Phase Power/Energy Meter with Tamper Detection http://www.atmel.com/dyn/resources/prod_do...nts/doc2566.pdf While the above references may not be exact for your project, I think that some of the information they provide will be helpful to you.
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