Specifications

DC Drives Overview
Silicon Controlled Rectified
(SCR) drives are excellent
for your everyday DC
brushed applications.
They have been very pop-
ular for more than a
decade and are low cost.
Typically, SCR drives have
60:1 speed ranges and
form factors of 1.37 at
base. Applications involv-
ing variable speed in a
single direction on an AC
line are well suited for
SCR drives.
Pulse Width Modulated (PWM) drives perform well in similar applications as SCR dri-
ves with several more advantages. PWM drives add more flexibility to applications by
being able to run on either AC or DC voltage. Their power devices switch at a rate
over 120 times faster than SCR power devices thus producing “cleaner” DC voltages.
A “clean” voltage means your motor will run cooler and quieter over a wider speed
range (100:1 compared to 60:1 of SCR drives). A cooler brushed DC motor will
require less maintenance to replace the brushes. The higher switching frequency is
above the audible range, so there is no hum from the motor. The wider speed range
allows you to run the motor slower while maintaining control. Applications requiring
cool, quiet, lower maintenance operation are perfect for PWM drives.
For AC motor and control information, see page 49.
For Brushless control information, see page 67.
Regenerative drives have the ability to turn the mechanical energy required to brake a DC
brushed motor back into electrical energy. They do this by electrically reversing or braking DC
brushed motors at a user-defined rate. Therefore, there are no mechanical relays or resistors to
wire or wear out. By being able to control torque in the opposite direction of speed, Regenerative
drives can control overhauling loads caused by gravity or inertia. Minarik Regenerative drives run
on either SCR or PWM technology, giving you more options to choose from. Any application that
requires reversing, braking, or the control of overhauling loads should use a Regenerative drive.
Drives
REGENERATIVE
Drives
SCR
Drives
PWM
0 11
Call us toll free 1•800•MINARIK or download manuals at www.minarikdrives.com
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REFERENCE