AS 60034.12:2009 pdf – Rotating electrical machines Part 12: Starting performance of single-speed three-phase cage induction motors.
For motors with type of protection ‘e’, locked rotor apparent power shall be in accordance with the appropriate values given in table 6
6.3 StartIng requirements
Motors shall be capable of withstanding two starts in succession (coasting to rest between starts) from cold conditions and one start from hot after running at rated conditions, The retarding torque due to the driven load will be in each case proportional to the square of the speed and equal to the rated torque at rated speed with the external inertia given in table 3 or table 7.
In each case, a further start is permissible only if the motor temperature before starting does not exceed the steady temperature at rated load. However, for 2-pole motors with type of protection ‘e — increased safety’ having a rated output greater than 100 kW, the retarding torque due to the driven load is proportional to the square of the speed and equal to 70 % rated torque at rated speed, with the external inertia given in table 7. After this starting. load with rated torque is possible.
NOTE It should be recognized that the number of starts should be minimized since these affect the life ot the motor.
7 Design NY starting requirements
The starting requirements are as for design N. In addition, however, a reduced retarding torque is necessary as the starting torque in ‘star connection’ may be insufficient to accelerate some loads to an acceptable speed.
NOTE It should be recognized that the number of starts should be minimized since these affect the life of the motor.
8 Design H requirements
8.1 Starting torque
The starting torque is represented by three characteristic features These featurest shall be in accordance with the appropriate values given in table 4. These values are minimum values at rated voltage. Higher values are allowed.
8.2 Locked rotor apparent power
The lacked rotor apparent power shall be not greater than the appropriate value given in table 2. The values in table 2 are independent of the number of poles and are maximum values at rated voltage.
8.3 Starting requirements
Motors shall be capable of withstanding two starts in succession (coasting to rest between starts) from cold conditions, and one start from hot after running at rated conditions, The retarding torque due to the driven load is assumed to be constant and equal to rated torque, independent of speed, with an external inertia of 50 % of the values given in table 3.
In each case, a further start is permissible only if the motor temperature before starting does not exceed the steady temperature at rated load.
NOTE It should be recognized that the number of starts should be minimized since these affect the life of the motor.
AS 60034.12:2009 pdf – Rotating electrical machines Part 12: Starting performance of single-speed three-phase cage induction motors
