Rockwell Automation 9VT201-007HTNNN, User Manual, Page: 200 / 224

C-4 Application Notes
Publication 9VT-UM001D-EN-P
Overspeed Limit is a user programmable value that allows operation at
maximum speed, but also provides an “overspeed band” that will allow a
speed regulator such as slip compensation to increase the output
frequency above maximum speed in order to maintain maximum motor
speed.
The figure below illustrates a typical Custom V/Hz profile. Minimum
Speed is entered in Hertz and determines the lower speed reference limit
during normal operation. Maximum Speed is entered in Hertz and
determines the upper speed reference limit. The two “Speed” parameters
only limit the speed reference and not the output frequency.
The actual output frequency at maximum speed reference is the sum of
the speed reference plus “speed adder” components from functions such
as slip compensation.
The Overspeed Limit is entered in Hertz and added to Maximum Speed
and the sum of the two (Speed Limit) limit the output frequency. This
sum (Speed Limit) must is compared to Maximum Frequency and an
alarm is initiated which prevents operation if the Speed Limit exceeds
Maximum Frequency.
Overspeed
Frequency
Output V
oltage
N ote 1: The lower limit on this range can be 0 depending on the value of S peed A dder
Overspeed
Limit
Frequency Trim
due to
S peed
Control M ode
M aximum
Voltage
M otor N P
Voltage
R un
Boost
Break
Voltage
S tart
Boost
A llowable Output Frequency R ange - N ormal Operation 1
A llowable S peed R eference R ange
A llowable Output Frequency R ange -
Bus R egulation or Current Limit
M aximum
Frequency
M otor N P Hz 0 Break
Frequency
M aximum
S peed
M inimum
S peed
Output
Frequency
Limit