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Shunt motor & torque speeds

A shunt DC motor is supplied by 300 V DC. The armature resistance of the
motor is Ra= 0.5Ω,field resistance Rfis 150Ω. Radj
is connected in series to the field.Radj may be varied from 0 to 300Ω and is currently set at 100Ω.
Armature reactio nmay be ignored in this machine. The magnetization curve for this motor,taken at a speed of 1200 rpm, is given in the table below:

Ea 10 200 250 280 295 325
If 0 0.7 1.0 1.3 1.6 2.5

whats the motor speed when armature current is 20A ?

answer should be 1289rpm, im getting well above this as in 3times as much? :frown: