Altivar 16 AC Drive Torque characteristics, thermal protection, special applications Torque Characteristics (typical curves) The curves below show the continuous torque and transient overtorque capabilities both with a self-ventilated motor and with a force-ventilated motor. The difference is in the ability of the force-ventilated motor to supply torque below half speed without danger of motor overheating. T/Tn 1.75 1.50 1.25 1 0.95 0.75 0.50 1 Self-ventilated motor: continuous useful torque [1] 2 Force-ventilated motor:
continuous useful torque Γ 0.25 3 Transient overtorque [2] 0 0 25/30 50/60 75/90 100/120 f (Hz) 4 Torque during overspeed at constant power [3] [1] For fractional powers 1/3 hp (250 W), the derating is less (20 % instead of 50 % at the lowest frequency). [2] Overtorque is limited to 110% Tn with the variable torque or high speed motor option cards. [3] With one of the display/adjustment options, the nominal motor frequency and the maximum output frequency can be adjusted from 40 to 200 Hz (see page 16). Caution : consult motor manufacturer before operating motor above rated speed. Note :
The maximum output frequency can be adjusted up to 400 Hz for use with a special motor by using the high speed motor option card and one of the display/adjustment options. Motor Thermal Overload Protection By continuously calculating I 2 t (I being the current to the motor), thermal overload protection of the motor is insured in the following conditions: - Ambient motor temperature +104 ° F (+40 ° C) - Frequency range is between 25/30 Hz and 50/60 Hz with a self-ventilated motor - Nominal motor current = 0.9 times the continuous output current of the drive (factory preset). If the nominal motor current is different, use one of the display/adjustment options.
If the ambient motor temperature exceeds 104 ° F (40 ° C), or if a self-ventilated motor is run at low speed, external thermal overload protection should be provided. Special Applications G When motor power is different from drive rated power, it is permissible for motor power to be less than or equal to drive rated power. When motor power is slightly higher than drive rated power, insure that the motor current is not higher than the continuous drive output current. G Motors in parallel: Drive rated power must be greater than or equal to the sum of the powers of the motors connected to the drive.
In this case, it is necessary to provide separate overload protection by thermal sensor or relay. If there are three or more motors in parallel, installation of a three-phase inductor between the drive controller and the motor is recommended. G Connection of an additional motor downstream from the drive: Motor can be connected downstream while drive is running if the power of the motor is less than that of the drive, and if the overload is acceptable (peak current is less than or equal to the maximum transient drive current). G Use with special motors: - Brake motor or tapered rotor motor: may be used. - Synchronous reluctance motor:
slip compensation must be overriden with one of the display/adjustment options. - Motor with a nominal frequency other than 50/60 Hz: use the display/adjustment option to adjust the nominal motor frequency. 6 3 2 1 4