Vacon 100 HVAC, Applications Manual

Page: 114 / 201

P3.1.2.6 MOTOR PREHEAT FUNCTION (ID 1226)
Use this parameter to set the temperature limit of the Motor Preheat function.
When the heatsink temperature or the measured motor temperature goes below this level,
motor preheat becomes active.
P3.1.2.7 MOTOR PREHEAT CURRENT (ID 1227)
Use this parameter to set the DC current of the Motor Preheat function.
P3.1.2.8 U/F RATIO SELECTION (ID 108)
Use this parameter to set the type of the U/f curve between zero frequency and the field
weakening point.
Selection
number
Selection name Description
0 Linear
The voltage of the motor changes linearly as a function of the
output frequency. The voltage changes from the value of
P3.1.2.4 (Zero Frequency Voltage) to the value of Voltage at
Field Weakening Point at a frequency set in Field Weakening
Point Frequency. Use this default setting if a different setting
is not necessary.
1 Squared
The voltage of the motor changes from the value of P3.1.2.4
(Zero Frequency Voltage) to the value of Field Weakening
Point Frequency at a squared curve. The motor operates
undermagnetised below the field weakening point and pro-
duces less torque. You can use the squared U/f ratio in appli-
cations where the torque demand is in relation to the square
of the speed, for example in centrifugal fans and pumps.
VACON · 114 PARAMETER DESCRIPTIONS
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