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Rockwell Automation Publication 2198-UM002E-EN-P - February 2018
Appendix D
Motor Control Feature Support
Basic Volts/Hertz for Fan/Pump Applications
The Basic Volts/Hertz Fan/Pump (fan/pump) method is based on the Basic
Volts/Hertz (V/Hz) method, but is specifically tailored for fan/pump
applications.
Figure 157 - Output Voltage Equation
For maximum system efficiency, fan/pump loads use variable frequency drives
that are equipped with a specific V/Hz curve where voltage is proportional to
square of the frequency.
Figure 158 - Basic Volts/Hertz Fan/Pump Method
V
2
x
=
f
x
f
n
V
n
– V
boost
+ V
boost
Where:
V
x
= Output voltage
f
x
= Output frequency
V
n
= Rated voltage
F
n
= Rated frequency
V
boost
= Run boost voltage
Vo
lta
ge
Frequency (Hz)
Frequency,
max
Base Frequency,
(nameplate)
Base Voltage
(nameplate)
Run Boost
Voltage, max
TIP
The Fan/Pump control method supports the run-boost attribute, but does
not support break-voltage, break-frequency, or start-boost.