Answer Happy

(b) An elevator on a cruise ship is driven by a permanent magnet DC motor. You are required to diagnose a fault and you disconnect it from the supply. For testing, you draw power from the auxiliary battery, which outputs 225 V DC. You connect the motor and measure its rotational speed, which is 1,800 rpm. You want to run the test for a while, and the battery has a total capacity of 11.25 kWh. After running the motor on the battery for an hour at the above conditions, the battery state of charge has dropped by 4.35%. The battery cannot supply more than 105 A and the motor is coupled to a load with a counter-torque of 110 Nm. The motor's electrical constant is stated on the nameplate as ke = 0.5 V/(rad/s), but you don't trust the nameplate. Verify if the above electrical constant is correct or not. If not, determine if the torque provided by the motor would actually be enough to supply the load. [8 marks]