Allen-Bradley PowerFlex 70 Reference Manual page 30

Analog Inputs
[Analog In1 Hi]
[Analog In1 Lo]
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3. Multiply by the Volts/Hertz ratio
15 Hz x 0.16667 Volts/Hz = 2.5 Volts
Therefore the command frequency from 0 to 2.5 volts on the analog input will be
15 Hz. After 2.5 volts, the frequency will increase at a rate of 0.16667 volts per
hertz to 7.5 volts. After 7.5 volts on the analog input the frequency command will
remain at 45 Hertz.
Example 2:
Consider the following setup:
• [Anlg In Config], bit 0 = "0" (voltage)
• [Speed Ref A Sel] = "Analog In 1"
• [Analog In1 Hi] = 10V
• [Analog In1 Lo] = 0V
• [Speed Ref A Hi] = 50hz
• [Speed Ref A Lo] = 0hz
• [Maximum Speed] = 45hz
• [Minimum Speed] = 15hz
The only change from Example 1 is the [Speed Ref A Hi] is changed to 50 Hz.
[Minimum Speed]
10V
Frequency Deadband
0-3 Volts
0V
0 Hz 15 Hz
Slope defined by (Analog Volts)/(Command Frequency)
[Speed Ref A Lo]
The deadband, as it relates to the analog input, can be calculated as follows:
1. The ratio of analog input volts to frequency (Volts/Hertz) needs to be
calculated. The voltage span on the analog input is 10 volts. The frequency
span is 60 Hz.
10 Volts/50 Hz = 0.2 Volts/Hz
2. Determine the frequency span between the minimum and maximum speed
limits and the Speed Ref A Hi and Lo.
[Speed Ref A Hi] – [Maximum Speed] = 50 – 45 = 5 Hz and . . .
[Minimum Speed] – [Speed Ref A Lo] = 15 – 0 = 15 Hz
3. Multiply by the volts/hertz ratio
5 Hz x 0.2 Volts/Hz = 1 Volt
15 Hz x 0.2 Volts/Hz = 3 Volts
Rockwell Automation Publication PFLEX-RM001H-EN-P - June 2013
Motor Operating Range
Command Frequency
[Maximum Speed]
Frequency Deadband
9-10 Volts
45 Hz 50 Hz
[Speed Ref A Hi]