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Converting DC motor and Drive to AC motor and drive

Converting DC motor and Drive to AC motor and drive

Converting DC motor and Drive to AC motor and drive

(OP)
How do I calculate the toruqe required and the HP required for  a DC motor to be replaced with AC motor and Drive. the Dc motor is of 90hp, 1500 rpm drives an extruder.

RE: Converting DC motor and Drive to AC motor and drive

ysn,
Three things determine the torque produced by an AC induction motor;
1= the strength of the magnetic field of the stator
2= the strength of the magnetic field of the rotor
3= the phase angle difference between rotor and stator fields.
There are several formulas for configuring the info you request, try your local electrical parts dealer for a copy of Uglys engineers pocket reference guides,inside you will find several formulas for conversion needs,also Delmars Textbooks are an excellent source for this info, hope this helps.
JB

RE: Converting DC motor and Drive to AC motor and drive

Is the extruder started loaded or unloaded?  What was the starting torque of the DC motor? 90X5250/1500=315ft/pds of torque running.  Suppose you are using 50Hz., since the 1500RPM.  Some DC motors have high starting torque, higher than their AC equivalents.  Most Design B motors, according the MG-1 NEMA have a 150% locked rotor torque or better.

RE: Converting DC motor and Drive to AC motor and drive

(OP)
Hi Forkel,
thanks for the info, it goves me some idea, how i go about it, the extruder starts at no-load

RE: Converting DC motor and Drive to AC motor and drive

Suggestion:
Torque in lb.-ft = 90HP x 5250 / 1500RPM = 315 lb-ft
Try Baldor motor:
75HP
460V
60Hz
332 lb-ft Full load torque
1160RPM
1.15 S.F.
1684M Type
16X92 Winding Number
ECP4404T-4 Catalog Number

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