A shunt$-$connected $75$kW$,250$V DC motor has an armature resistance of $45$mohm and a field resistance of $185$ohm. When operated at $250$V its no$-$load speed is $1850$rpm$.$ The motor is operating under load at a terminal voltage of $250$V and a terminal current of $290$A$.$

Calculate the motor speed, load power, load torque in this operation point.

Assuming the load torque remains constant as a function of speed, calculate the motor speed if the terminal voltage is reduced to $200$V$.$