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Responding to Ramesh's, Sun, Nov 17, 2:32 pm, query. This subject was covered in great detail in an earlier thread. Proper measurement is dependent on parameters used. For example, If you used phase-to-phase voltage and line current to provide measurement of one phase, then, the result...

Responding to Claudio's Nov 13, query: A VFD can certainly be considered. One possible pitfall is the assumption that shorting of the slip-rings is all that is required. This approach is only true if the resistance of the rotor-winding alone can provide adequate starting-torque. I...

Responding to Ashok's Mon, Nov 18, 9:54 am, query: In the USA the document covering "Standard Nominal System Voltages" Is ANSI (American National Standards Institute) C84.1-1989. Three voltage classifications are defined: o low =, < 1000 V. o medium, > 1000 but =/< 100 kV. o high...

Responding to Ken Brown's Mon, Nov 11, 10:30 am, comments: While I can't impute your observations, I have some reservation about the general conclusions regarding TEFC capability under standstill conditions: a) Stator Winding Loss. Based on full current, even at standstill, the loss is...

Responding to Walt Boyes reply: Are you sure that conductor alignment relative to magnetic lines of force is not crucial. I thought the induced current was related to the "Dot" product of the two vectors, AxBxCos(phi)! If vectors are parallel,the product is zero. Regards, Phil Corso, PE...

Responding to Leon Vangorp's query: It amazes me that this problem still persists after some 40+ years of this technology. I suggest the following: The three solutions I have found to be most effective are: a) install current-limiting breakers or fuses; b) introduce small inductors...

Responding to Madhukar Parikh's query: Liquid rheostats as variable resistors were often used in the 'g'olden days for motor-starting and even for speed-control. Today they are mostly used to test generators. Essentially they consist of a set of movable and fixed electrodes immersed in an...

Responding to Wm Hinton's (Wed, Oct 9, 1:03pm) comment: I strongly disagree with you about delta-wound motors being more forgiving in this situaton. From a qualitative viewpoint, starting time is excessive. If you want a quantitative viewpoint, please furnish particulars, especially...

Reponding to Rajkumar's query: Can you provide country of installation, i.e., USA, Canada, European, etc? Also, any special duty, eg, mining, marine, etc. Regards, Phil Corso, PE (Boca Raton, FL)

Power factor does not "effect" operation of an induction motor! Instead, the motor "causes" it! The electrical input to an ordinary induction motor is comprised of two components. One is called the "real" power (W) component. It provides the power for producing shaft output as well as any...

Tao: I'm not sure from your reply that you have the solution or that you still need one. If the former, then, ignore this message. If the latter, then, L1, L2, and L0 represent positive, negative, and zero sequence inductances, respectively, as determined by the theory of "Symmetrical...

Further to my earlier response to Kevin Leow: If, on the other hand, you want to do the calculation, because, like the mountain climber, it is there (or because you are a typical engineer in search of truth), I suggest you contact a Siemens rep. Some years ago, Siemens' produced a book...

Most on the list would ask "Why do it"? That said, then, lacking detail regarding length, spacing, orientation, parameters, construction, etc, all that anyone can provide at this point are Rules-Of-Thumb. The one precaution that is most often overlooked is the inductive effect of...

Responding to Bob Peterson's, Tue, Sep 24, 10:21 am, "define" query: That's easy. Paraphrasing our ex-president... it is based on how one who knows, knows. Seriously, just answer the question, "Bob, are you a "Qualified Person" as defined by the NEC?" Regards, Phil Corso, PE (Boca...

Re my Fri, Sep 20, 9:32 pm, comment to Tao Yang: A very big OOPS (the most feared word in an operating room)! I apologize for submitting the wrong data. I supplied data for an induction motor. For a permanent-magnet synchronous motor, the Ld and Lq inductance values can be derived from...

Responding to Prasanna's Fri, Sep 20, 10:28 am, query: DOL, or Direct-On-Line starting, will not enhance a motor's design starting characteristics, unless a higher than nominal voltage is applied. The fact that the load is high-inertia does not influence break-away torque. Nor does it...

Responding to P. Chatterjee's Aug 28, query: Connecting two transformers to the same primary isolator will not produce any detrimental effects during "switch off". This arrangement is common industrial practice for much larger transformers having higher primary voltages! However, there is...

The direct-axis and quadrature-axis inductances are (L1+Lm) and (L2+Lm) respectively. Of course, L1 and L2 are derived from the stator and rotor (referred to stator) reactances, respectively. Regards, Phil Corso, PE (Boca Raton, FL)

Don't know your location but in the USA about any Electrical Supply Co. should carry what you need. Some manufacturers are Acme, Dongan, GE, SqD, Staco. However, your specified input/output voltage, is not typical of an off-the-shelf unit. Usually the input is stated as a range, eg, 95-135...

Responding to Phenol's (Fri, Sep 13, 11:31 am) query: Search List archive for R. Foster's excellent treatise on the general subject of reduced-voltage starting. About the only thing I can contribute are very rough relative-cost factors, devoid of size, and installation, specifics: 1) Full...