Pete, if I understand this correctly.(S= R2/X)which defines the maximium torque and power of which happends when S = 1 when R2 match with X. I do not see that being consistant with the torque VS. Speed graph. because when S = 1 (RPM=0) thats when motor is energized and right before take off...
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"airgap torque is maximized when airgap power is maximized, which occurs when the component R2/s matches the source impedance X.... i.e s = R2/X"
if that is the case, then if I take the first derivative of the P_gap with respective to S. I should recieve the same Resistance and Slip...
never mind again.....I got it .....
I just realized how much I have forgotten over the years ....maybe because I was probably never good at it the first place
sorry for the confussion
to be more specific , comparing a S-cage motor to a slip ring motor....additional resistance are added to the rotor resistance to increase starting torque ( during take-off) of which will limit the inrush current.. but since Power is equal to torque * internal angular velocity W( when slip equal...
Pete, would you please show me the expressions of current , power , turque in terms of S ( in Zero to Breakdown Torque region )
since you first common , I have went back looking into couple books but yet , I am still having a hard to making connection between them Thanks
knowing Squirrel cage have high inrush current due to low rotor impedence and rotor impedence is equal to
Xrotor + Rrotor and since X = jWL = j 2 pi f L
Rotor impedence is at its max when f reachs the high point and vis versa, and as the (which above I can prove mathmatically)
""Rotor...
guys, .....question ...this might sound very elemetry but, I had to ask
what determines the type of VFD set??(constant torque, constatnt speed, constant power)
is it set by changing the drive parameter ??? or it is determine by the type of load or the motor??
I have a pump and its power cable was cut by the conduit during the installation. what are my options here??? is there any "Kit" out there can patch up power cables ??? I have tried to Google it and nothing shows up, so any ideas ???
Guys, What I meant in the oringinal question was that is there a wiring difference?? when constructing a motor, does the engineer choice from a pool of 50Hz & 60Hz stators & rotors???? or just choice a stators or rotors with diffenent dimesions and construct the motor according to the needs??? I...
guys, is there really a phsical difference in the 50Hz and 60Hz Motor ??? I always though that they are just rated differently, and what I meant by that is since they are made to be used in a country thats either 50 or 60 hz therefore they are factory test and rated at that frequency. thus if...
Skogsgurra,
I am thinking that the VFD put out 0 ~60 HZ regardless of the VFD frequency setting and the frequency setting requaird, so that the VFD can calculate the motor operating RPM based on the output frequency ( 0 ~60 HZ ) and make such information avliable to the user.
please let me...