PowerTec Regenerative Brushless DC Motor Control 1000AR - Manual (Page 2)

Model 1000AR Installation and Operation Manual P AGE
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OFFICIAL 6/4/2001
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NTRODUCTION
WHAT IS A GENESIS SERIES BRUSHLESS DC DRIVE ?
The GENESIS series of Brushless DC (BLDC) motor controls (drives) were developed to operate very
large Brushless DC motors. Large BLDC motors were first made by POWERTEC Industrial Corporation in the
late 1980’s. POWERTEC was acquired by Powertec in 1993.
Small BLDC motors have been in use for many years. The GENESIS series were the first drives
produced to operate really large BLDC motors. They range from fractional Horsepower (HP) to 300 HP.
Brushless DC motors and drives offer three significant benefits to the user:
Absolute Speed Control
High Efficiency
Low Maintenance.
ABSO LUTE SPEED CO NTRO L
The AC induction motor must slow down, or “slip”, in order to develop torque. The amount of slip varies
with the load on the motor. When the load changes from no load to full load, speed may change by as much
as 50 RPM. You must use extraordinary means to employ AC motors in speed sensitive applications.
Traditional brush-type DC motors have “IR Losses” that causes the speed of the motor to vary as the
load changes. “IR Losses” cause speed changes of as much as 2% of base speed. You can limit speed
changes to about 0.5% with a very expensive tachometer. That is still 8 or 9 RPM from no load to full load.
You must use extraordinary means to employ brush-type DC motors in speed sensitive applications.
Brushless DC drives and motors do not change speed when the load changes. This is true with the
standard product, right out of the box! This is very good for speed sensitive applications.
HI G H EFFI CI ENCY
AC induction motors are relatively efficient when operated across the line on plant power. Using an AC
variable speed inverter to control the speed of the motor adds power losses as heat in the drive. It also
creates additional losses in the motor. At the 100HP level, the total losses in the AC system approach 10%.
Brush-type DC motor systems at 100 HP are relatively efficient, but the losses total about 8%.
Brushless DC systems at the 100 HP level average less than 6%.
At 100 HP, each percentage of losses is 750 watts. That’s 18 KiloWatt-Hours (KWH) per day, or about
6,500 KWH per year. A 2% difference in efficiency results in over $1,000 a year in direct energy savings.
LO W M AI NTENANCE
AC induction motors running on variable speed AC drives produce a lot of heat. The motors require more
frequent lubrication. They also need extra bearing changes. Heat also shortens the life of the motor.
Brush-type DC motors require frequent brush replacement. They also need commutator service and field
and armature rewinding. They also require frequent lubrication and bearing changes due to heat.
Brushless DC motors require lubrication. However, the oversize bearings and the low heat production in
the motor allow long bearing life. Maintenance on a Brushless DC motor is minimal.
POWERTEC offers the GENESIS series for general purpose industrial use.
POWERTEC also offers a complete line of servo-duty rated drives and motors covering the range from
1/10 to 300 HP.
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