Rockwell Automation RELIANCE ELECTRIC SP500 - Page 76

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.
100 |W
~ S
xt &
© = L
g = ca x is
Ss oF We
3
6
Base 240
Frequency FREQUENCY (Hz)
Figure 8.2 — Volts/Hertz Curve
F-08 RPM at Base Speed
This parameter scales Parameter Range: 10 to 9999
the RPM display and a
the setpoint to a user- Default Setting: 1750
specified engineering Step Size: 1.0 unit
unit.
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).
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:
F-08
= Di | 07 Displayed Value Present Operating Speed (Hz) x
At 30 Hz, the RPM display will show 875:
1750 _
30 (Hz) x 60 7 875
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:
20
30 (Hz) x 60" = 10
8-8 SP500 AC Drive Installation and Operation Manual Version 3.1