Lenze I51AE175F User Manual

8.2.1.2 Square-law V/f characterisc
The square-law V/f characterisc is typically used in heang, venlaon and climate applica-
ons to control the speed of fans and pumps.
Details
Each applicaon that is provided with the features according to the anity laws may possibly
benet from a square-law V/f characterisc.
The anity laws describe the relaon between the speed and other variables:
•
The volume ow increases proporonately to the speed.
•
The required pressure behaves proporonately to the square of the speed.
•
The power input is proporonately to the cube of the speed. This means that already a
minimal reducon of the speed may lead to substanal savings in energy consumpon.
0
[%]
[%]
0 50 100
50
100
0
[%]
[%]
0 50 100
50
100
0
[%]
[%]
0 50 100
50
100
SpeedSpeedSpeed
Power inputPressureVolume flow
By approximaon, the square-law V/f characterisc corresponds to the curve for power input
shown above. At low frequencies, the voltage is reduced since due to the type of load a lower
voltage is sucient to generate the required power. All in all, this results in an energy-ecient
system.
Select V/f characterisc control with square-law characterisc:
1.
Motor control mode 0x2C00 (P300.00) = "V/f characterisc control (VFC open loop) [6]"
2.
V/f characterisc shape 0x2B00 (P302.00) = "Quadrac [1]"
Seng of the V/f characterisc:
•
Liming factors for the V/f characterisc are rated mains voltage 0x2540:001 (P208.01),
minimum frequency 0x2915 (P210.00) and maximum frequency 0x2916 (P211.00).
•
The base voltage 0x2B01:001 (P303.01) is usually set to the rated motor voltage (motor
nameplate data). The base voltage is preset to the rated mains voltage. This again is preset
according to the product key of the inverter. 4Mains voltage ^ 95
•
The base frequency 0x2B01:002 (P303.02) is usually set to the rated motor frequency
(motor nameplate data).
0
[V]
[Hz]
0
0x2540 001:
0x2B01 001:
0x2B01 002:
0x29160x2915
The current output frequency can exceed the set maximum frequency if the
gain for the slip compensaon in 0x2B09:001 (P315.01) is set to a value higher
than 0.
Next steps
•
The inverter provides dierent funcons by means of which the drive behaviour can be
further opmised.4Opmisaon of motor control ^ 129
•
An opmisaon of the control loops is not mandatory for this motor control type but may
lead to a
beer control mode. 4Opmisaon of the control loops ^ 140
Motor control
Motor control selecon
V/f characterisc control (VFC)
118

Lenze I51AE175F Specifications

General

Brand	Lenze
Model	I51AE175F
Category	Inverter
Language	English