If the protection device is bimetalic type then it takes a few seconds to get heated up before tripping off. In case of other advanced type of protection devices, there could be a preset timer to allow a certain amount of high starting current. In both the cases, the avoidence of tripping during starting is by design, since it is known that the motor takes a high starting current.
While starting a motor from standstill to its rated speed, the motor has to overcome the inertia and generate enough torque to over come it. In the process the motor takes higher current during the starting. Once started and set in motion the current reduces ti its normal value. Full load current is lower than the starting current normally.
How do you calculate voltage drop for starting motor current
Motor starting current is typically 5-7 times the rated current of the motor. (For three phase induction motors)
what is the starting current of 2ton window ac voltas
The starting current is high because when the motor is not rotating no back-emf is generated, leaving the starting current to be determined by the armature resistance, which should be low.
A series-wound commutator motor has the best starting torque because the torque is proportional to the square of the current, and the starting current is set by a current-limiting resistor which is switched out as the motor builds up speed.
Assuming the Motor is IE1 Efficiency and 4 Poles, the in rush current will be 1183 A
because of starting current of induction motor is very high and it damages the insulation of motor
Full load starting current is typically in the region of 5or 6 times the full load motor current;.
starting current of 3 phase 75 KW induction motor
depending on kva class of the motor between 4-8 times the running current
Across the line starting of a motor can be as high as 300% of the full load amps.