Types of Drives
The main types of drives that are commonly available are:
AC drive system: AC drive refers to the device used to control the speed of an AC motor. The AC drive system consist of a converter, a regulator and an inverter. In an AC driver the electrons alternates in direction as the voltage force alternates between pushing and pulling of electrons.
DC drive system: A basic DC drive controller consist of a drive controller and DC motor. In DC systems, electrons flow continually in one direction. The drive controller converts AC power to DC power. DC drive is the speed control system of the DC motors.
Hydraulic drive system: It consist of a constant speed AC motor driving a hydraulic pump which in turn drives a hydraulic motor and the associated controls. The entire package is often referred as the hydrostatic drive.
Qualities of Drive
In the drive system alternating current or the direct current is converted into the required energy form. The main work of a drive is to maintain a constant speed of the screw throughout because the fluctuation of the screw will cause changes in the dimension of the extrudate. Thus, constancy of speed is a very important requirement of an extruder drive. The drive must supply the required amount of torque and must be able to continuously adjust from zero to maximum screw speed.
Today's motor design and construction are highly refined. A wide range of machines are available in the market that allows the operator to start, stop, and change direction and speed of the motor. Industrial drives are available in a variety of configurations and combinations. When one selects a motor one mus t ensure that the drive suits the requirement in terms of the the motor type, horse power, input voltage , etc.