Altivar Process 600 Variable Speed Drives Page 22 Application Information

22 Altivar Process 600 variable speed drives Application Information Additional Application Information Using Altivar Process 600 drives with synchronous motors Altivar Process drives are also suitable for powering synchronous motors with sinusoidal electromotive force. This drive/motor combination makes it possible to obtain remarkable accuracy and maximum torque. The design and construction of synchronous motors are such that they offer enhanced power density, high efficiency, and high-end torque in a compact footprint. Driving a synchronous motor with sinusoidal electromotive force without speed feedback. The entire range of Altivar Process variable speed drives can be used to power a synchronous motor with sinusoidal electromotive force without speed feedback. The performance level achieved is then comparable to that obtained with an asynchronous motor in sensorless flux vector control. Using special motors at high-speed These motors are designed for constant torque applications with high frequency ranges. The Altivar Process drive supports operating frequencies of up to 500 Hz. Through their design, this type of motor is more sensitive to overvoltages than a standard motor. Various solutions are available: Overvoltage limitation function Output filters The drive's 5-point voltage/frequency control ratio is particularly well-suited as it avoids resonance. Using a motor at overspeed When using a standardized asynchronous motor at overspeed, check the mechanical overspeed characteristics of the selected motor with the manufacturer. Above its nominal speed corresponding to a frequency of 50/60 Hz, the motor operates with a decreasing flux, and its torque decreases significantly. The application must be able to permit this type of low-torque, high-speed operation. 1. Machine torque (degressive torque) 2. Machine torque (low motor torque) 3. Continuous motor torque Typical applications : wood-working machinery, polishing and cutting machines. Power of self-cooled motor greater than the drive power This motor-drive combination makes it possible to use a self-cooled motor for a greater speed range in continuous operation. The use of a motor with a higher power rating than that of the drive is only possible if the current drawn by this motor is less than or equal to the nominal drive current. Note: Limit the motor power to the standard rating immediately above that of the drive. Example: On a single machine, the use of a 2.2 kW drive combined with a 3 kW motor means that the machine can operate at its nominal power (2.2 kW) at low speed. 1. Motor power = drive power = 2.2 kW 2. 2.2 kW drive combined with a 3 kW motor: greater speed range at 2.2 kW Connecting motors in parallel The nominal current of the drive must be greater than or equal to the sum of the currents of the motors to be controlled. In this case, provide external thermal protection for each motor using probes or thermal overload relays. For cable runs over a certain length, taking account of all the tap links, it is advisable either to install an output filter between the drive and the motors or to use the overvoltage limitation function. If several motors are used in parallel, there are two possible scenarios: The motors have equal power ratings, in which case the torque characteristics will remain optimized after the drive has been configured The motors have different power ratings, in which case the torque characteristics will not be optimized for all the motors Using a motor at constant torque up to 87/104 Hz A 400 V, 50 Hz motor in connection can be used at constant torque up to 87 Hz if it is in r connection. In this particular case, the initial motor power and the power of the first associated drive are multiplied by (it is therefore important to select a drive with a suitable rating). Example: A 2.2 kW 50 Hz motor in connection supplies 3.8 kW at 87 Hz with a r connection. Note: Check the overspeed operating characteristics of the motor.

Previous Page
Next Page