Final answer:
The scenario involves calculating the safe mechanical load torque for a specified induction motor under a condition where voltage and frequency drop by 40%. torque is proportional to the square of the voltage hence a 40% reduction results in 36% of the normal torque capability. other factors like slip and synchronous speed relation must also be considered for a precise calculation.
Step-by-step explanation:
The question relates to an electrical engineering scenario where an induction motor's ability to handle load under reduced voltage and frequency conditions without stalling is assessed. Given a 440-V, 3-phase, 6-pole, 50-Hz, delta-connected induction motor with equivalent-circuit parameters of RI=0.2Ω; R2'=0.18Ω; X1=X2'=0.58Ω, we're asked what mechanical load torque it can safely drive when subjected to a 40% drop in both voltage and frequency. To determine the maximum tolerated mechanical load torque, one would typically calculate the starting torque at the reduced voltage and use that as an approximation for the maximum load torque under these conditions, assuming it does not exceed the normal operating torque. Since the induction motor's torque is proportional to the square of the voltage, a 40% drop in voltage results in a (0.6)^2=0.36 or 36% of the normal voltage torque capability. Given that torque is also affected by frequency through the slip and synchronous speed relation, this factor would need to be taken into account alongside values such as resistance and reactance for a precise calculation.