ELECTRIC INDUCTION MOTOR DESIGN: IEC MOTOR DESIGN LETTER GUIDE
What are the motor design types that are provided by IEC?
Motors covered by this IEC standard are classified by the following designs:
Design N
Normal torque three-phase cage induction motors intended for direct-online starting, having 2, 4, 6, or 8 poles and rated from 0.4 kW to 630 kW at frequencies of 50 Hz or 60 Hz.
Design NY
Motors similar to design N, but intended for star-delta starting. For these motors in star-connection, minimum values for Tl and TU of 25% of the values of design N may be expected.
Design HY
Motors similar to design H but intended for star-delta starting. For these motors in star-connection, minimum values for T1 and TU of 25% of the values of Design H may be expected.
source: 2010 IIEE Technical Manuals for Electric Motors
What are the motor design types that are provided by IEC?
Motors covered by this IEC standard are classified by the following designs:
Design N
Normal torque three-phase cage induction motors intended for direct-online starting, having 2, 4, 6, or 8 poles and rated from 0.4 kW to 630 kW at frequencies of 50 Hz or 60 Hz.
Design NY
Motors similar to design N, but intended for star-delta starting. For these motors in star-connection, minimum values for Tl and TU of 25% of the values of design N may be expected.
Design H
High torque three-phase cage induction motors with 4, 6 or 8 poles, intended for Direct-online starting, and rated from 0.4 kW to 160 kW at a frequency of 60 Hz. Torques of IEC Design H are nearly identical to NEMA Design C.
High torque three-phase cage induction motors with 4, 6 or 8 poles, intended for Direct-online starting, and rated from 0.4 kW to 160 kW at a frequency of 60 Hz. Torques of IEC Design H are nearly identical to NEMA Design C.
Design HY
Motors similar to design H but intended for star-delta starting. For these motors in star-connection, minimum values for T1 and TU of 25% of the values of Design H may be expected.
Design N starting torque
The starting torque is represented by the locked rotor torque Tl, pull-up torque Tu and breakdown torque Tb, each expressed as a per unit value of the rated torque TN, and shall be in accordance with the appropriate values. These values are minimum values at rated voltage, with no tolerance. Higher values are allowed. The starting torque at any speed between zero and that at which breakdown torque occurs shall be not less than 1.3 times the torque obtained from a curve varying as the square of the speed and being equal to rated torque at rated speed.
The starting torque is represented by the locked rotor torque Tl, pull-up torque Tu and breakdown torque Tb, each expressed as a per unit value of the rated torque TN, and shall be in accordance with the appropriate values. These values are minimum values at rated voltage, with no tolerance. Higher values are allowed. The starting torque at any speed between zero and that at which breakdown torque occurs shall be not less than 1.3 times the torque obtained from a curve varying as the square of the speed and being equal to rated torque at rated speed.
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' may be insufficient to accelerate some loads to an acceptable speed.
The starting requirements are as for design N. In addition, however, a reduced retarding torque is necessary as the starting torque in 'star' may be insufficient to accelerate some loads to an acceptable speed.
Design H starting torque
The starting torque is represented by the locked rotor torque Tl, pull-up torque TU and breakdown torque Tb, each expressed as a per unit value of the rated torque TN, and shall be in accordance with the appropriate values - Minimum values of torques for Design H starting performance. These values given are per unit TN. These values are minimum values at rated voltage, with no tolerance. Higher values are allowed.
The starting torque is represented by the locked rotor torque Tl, pull-up torque TU and breakdown torque Tb, each expressed as a per unit value of the rated torque TN, and shall be in accordance with the appropriate values - Minimum values of torques for Design H starting performance. These values given are per unit TN. These values are minimum values at rated voltage, with no tolerance. Higher values are allowed.
Design HY starting requirements
The starting requirements are as for design H. In addition, however, a reduced retarding torque is necessary as the starting torque in 'star' may be insufficient to accelerate some loads to an acceptable speed.
The starting requirements are as for design H. In addition, however, a reduced retarding torque is necessary as the starting torque in 'star' may be insufficient to accelerate some loads to an acceptable speed.
EXCELLENT EXPLANATION ON IEC MOTOR DESIGN LETTER GUIDE. IT WOULD HAVE BEEN MORE USEFUL IF THOSE LETTERS WERE SHOWN BEING COMPARED WITH EQUIVALENT NEMA LETTER CODE.
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