Rockwell Automation 20G PowerFlex 750-Series AC Drives - Manual (Page 38)

38 Rockwell Automation Publication 750-RM002B-EN-P - September 2013
Chapter 1 Drive Configuration
Individual Tests
Some of the following tests are executed during an Autotune.
Resistance Test
This test is a Static test whether Static or Rotate is selected. Used to measure
Stator resistance.
Inductance Tests
This test is a Static test whether Static or Rotate is selected. One test is used for
Induction motors and a another is used for PM motors. The result from the
Induction test is placed into the Ixo parameter and the PM test is placed into the
IXd and IXq parameters.
Flux Test
This test is a Rotate test that measures the current under a no load condition. The
results are used for the flux current. If a Static test is used, the resulting value is
from a lookup table.
Slip Test
This test is a Rotate test that measures the difference between the rotor speed and
the stator speed. This measurement is taken during acceleration.
PM Offset Test
This test can create a small amount of motor movement so it needs to be
performed with the Rotate selection. The test reads the encoder position when
the drive outputs zero hertz.
Inertia Test
This test is a stand alone test that is used to measure the system inertia.
The drive sets this value in P76 [Total Inertia] as seconds of inertia. This reflects
the time it takes to accelerate the load at 100% torque to base speed. This
information can be very useful in determining the total inertia (in lb•ft
2
) that is
connected to a motor shaft.
Using the following formula,
and rearranging it to
Tacc
WK 2 ΔN ×
308 t
( )
------------------------- =
WK 2
Tacc 308 t
( ) Ч Ч
ΔN
-------------------------------------- =