PowerTec 2000C Instruction Manual page 9

1.2 NON-REGEN
VERSUS REGEN
OPERATION
Page 1-2
voltage differences between the brushes and the motor control
output vary with load, speed varies with load. Extraordinary means
must be used to employ DC brush-type motors and solid-state SCR
controls in speed sensitive applications.
Even when a DC tachometer is used with a brush-type
DC motor to regulate speed (curve C in Figure 2), the ta-
chometer only reads an AVERAGE speed, and the resolution
between speeds limits the response.
The Brushless DC motor and control system overcomes these
problems to provide smooth and efficient power and speed control. Its
speed regulation is not measured in percentage of RPM, as is the
case with other types of motor and control systems, but in physical
shaft position within a single revolution. With a brush-type DC motor
and solid state SCR control, speed regulation of +/-0.5% might be
obtained with a very expensive tachometer. This means that a motor
set for 1750 RPM may be operating anywhere between 1741 RPM
and 1759 RPM and still be within specifications. A brushless DC
motor set for 1750 RPM must run at 1750 RPM, period. The only
alternative is to be in current limit. Short of current limit, the
Brushless DC motor may not be more than 240 degrees behind its no
load shaft position with the standard control set at its minimum gain.
The Brushless DC motor control looks not at its speed, it looks at
the motor shaft in relation to where it should be.
The Brushless DC motor control also can supply power when
and as needed at a rate which more than five times the solid-state
SCR control's line limited rate.
All of this comes in a compact package which will exceed the
performance of across the line operated AC motors, AC adjustable
frequency operated motors, or the conventional DC brush-type
motors.
POWERTEC's Brushless DC motors have the high reliability
and low maintenance requirements which have always been as-
sociated with AC induction motors. Brushless DC motors have
speed and torque control which are superior to the traditional brush-
type DC motor, plus a very high level of efficiency.
The Brushless DC motor and control give your industrial
applications outstanding performance, long life, and very efficient
service in the the most demanding industrial conditions.
The POWERTEC Models 2000C and 3000C are non-regen-
erative Brushless DC motor controls. They will not accept energy
coming from the motor due to overhauling loads and high inertias
during deceleration. The models 2000RG and 3000RG from POW-
ERTEC are regenerative. This section explains the difference.
When a motor is operating a load in such a way that it is
drawing current from the power supply, it is said to be operating in
the MOTORING mode. This is the most common mode of motor
Model 2000C/3000C Instruction Manual