Rockwell Automation SP500 AC Drive Installation and Operation Manual - Manual (Page 80)

8-8 SP500 AC Drive Installation and Operation Manual Version 3.1
F-07 V/Hz (Base Speed) (continued)
The V/Hz curve allows the drive to maintain a constant V/Hz ratio, providing constant
torque at any frequency. See figure 8.2.
This parameter defines the scaling value applied to the current speed before it is
displayed. It is also used to scale the local reference when F-18 is set to ON.
The value to enter into F-08 is the maximum value (in RPM, hertz, or any other
engineering unit) to be displayed when the drive is running at base speed (F-07).
Figure 8.2 – Volts/Hertz Curve
FREQUENCY (Hz)
0
240
100
Base
Frequency
O
utput V
oltage (%
)
Min
imu
m
M
a
x
im
u
m
V /
H
z
V
/
H
z
F-08 RPM at Base Speed
This parameter scales
the RPM display and
the setpoint to a user-
specified engineering
unit. Parameter Range:
Default Setting:
Step Size:
10 to 9999
1750
1.0 unit
Display Scaling Examples
Example 1: Assume that an application requires the display show 1750 RPM when the drive is running
at a base speed of 60 Hz. The RPM display is scaled according to the following equation:
At 30 Hz, the RPM display will show 875:
Example 2: Assume the application requires the display show 20 feet per minute for a conveyor (or 20
gallons per minute for a pump) when the motor is running at base speed (F-07= 60 Hz). Enter 20 in
parameter F-08 to scale the display.
At 30 Hz, the display will show 10 feet (or gallons) per minute:
Present Operating Speed (Hz) x = Displayed Value
F-08
F-07
30 (Hz) x = 875
1750
60
30 (Hz) x = 10
20
60