Welkon Ltd

When quality of Electric Motors matters.

Welkon Limited

Torque/Speed Model of TEFC Self-ventilated (IC411) Squirrel Cage Induction Motor controlled with Frequency Inverter.
Reduced Torque up to 80% of the Base Frequency and Constant Power (field weakening) after the Base Frequency (nominal speed) point.


SPEED = 0 rpm —>

Enter Motor Output and Speed:
The curve with zero deration is valid for class F/F.
If class F/B is to be maintained derate the Power by 10% (enter '10' in the Deration % field)!

Motor [kW]	Motor [rpm]	Deration [%]	B/down Torque [Nm]

If you are not going to control the speed well above the synchronous speed (in the field weakening mode) you do not need to fill the 'Breakdown Torque' value [Nm] in the above table.

However if you do then please be aware that the point where the 'Breakdown Torque' curve (violet) intersect the 'Torque' curve (blue) the range of "Constant Power" ends and after that the Breakdown Torque is the limiting Torque value the motor can achieve.

After the 'Torque'/'Breakdown Torque' intersection point the Power is reducing as you will see from the graph. If you know the motor 'Rated Torque' and the 'Breakdown Torque ratio' you can multiply the two numbers to get the 'Breakdown Torque' in "Nm":

Welkon Limited

Registered Address:
45 Oxford Street
Wellingborough
Northants NN8 4JH
United Kingdom
(not a Correspondence Address !)