AS 60034.12:2009 – Rotating electrical machines Part 12: Starting performance of single-speed three-phase cage induction motors.
5 Designation
5.1 General
Motors designed according to this standard are classified according to subclauses 5.2 to 5.5.
5.2 Design N
Normal starting torque three-phase cage induction motors intended for direct-on-line starting, having 2. 4. 6 or 8 poles and rated from 0,4 kW to 1 600 kW
53 Design NY
Motors similar to design N. but intended for star-delta starting. For these motors in star-
connection, minimum values for T and T are 25 % of the values of design N. see table 1.
5.4 DesIgn H
High starting torque three-phase cage induchon motors with 4. 6 or 8 poles, intended for direct-online starting, and rated from 0.4 kW to 160 kW.
5.5 Design HY
Motors similar to design H but intended for star-delta starting. For these motors in star- connection minimum values for ‘1 and T are 25 $ of the values of design H. see table 4.
6 Design N requirements
6.1 Torque characteristics
The starting torque is represented by three characteristic features. These features shall be in accordance with the appropriate values given in table I or table 5. The values in table 1 and table 5 are minimum values at rated voltage. Higher values
6.2 Locked rotor apparent power
The locked rotor apparent power shall be not greater than the appropriate value given in table 2 or table 6. The values given in table 2 and table 6 are independent of the number of poles and are maximum values at rated voltage For motors with type of protection e. locked rotor apparent power shall e in accordance with th 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 it 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 Uiouid be recognized ttI tie number of starts should be minimized since thes affect the life of th. 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 ihould be recognized that the number of staris ihould 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 locked 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 itfe of the motor.