Menu 21 Introduction Parameter x.00
Parameter
description format
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RTU
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Advanced parameter
descriptions
162 Commander SK Advanced User Guide
www.controltechniques.com Issue Number: 2
The motor rated current should be set at the machine nameplate value for rated current.
This value is used in the following:
Current limit, see Pr 21.29 on page 165
Motor protection system, see Pr 21.16 on page 165
Slip compensation, see Pr 21.08
Vector mode voltage control, see Pr 21.09
Dynamic V to f control, see Pr 5.13 on page 61
The rated full load rpm is used with the motor rated frequency and No. of poles to calculate the rated slip of the induction machine in Hz.
The rated slip is used to calculate the frequency adjustment required to compensate for slip from the following equation:
If slip compensation is required, Pr 5.27 must be set to a 1 and this parameter should be set to the nameplate value, which should give the correct
rpm for a hot machine.
Sometimes it will be necessary to adjust this when the drive is commissioned because the nameplate value may be inaccurate. Slip compensation will
operate correctly both below rated speed and within the field weakening region. Slip compensation is normally used to correct for the motor speed to
prevent speed variation with load. The rated load rpm can be set higher than synchronous speed to deliberately introduce speed droop. This can be
useful to aid load sharing with mechanically coupled motors.
If Pr 21.08 is set to 0 or to synchronous speed, slip compensation is disabled.
If the full load speed of the motor is above 9999rpm, slip compensation should be disabled. This is because a value above 9999 cannot be entered in
Pr 21.08.
The rated voltage is used in conjunction with the motor rated frequency (Pr 21.06) to define the voltage to frequency characteristic applied to the
motor. The following operating methods selected by Pr 5.14 are used to define the drive frequency to voltage characteristic.
Open-loop vector mode: Ur S, Ur A, Ur or Ur I
A linear characteristic is used from 0Hz to rated frequency, and then a constant voltage above rated frequency. When the drive operates between
rated frequency/50 and rated frequency/4, full vector based stator resistance (Rs) compensation is applied. However there is a delay of 0.5s when the
drive is enabled during which only partial vector based compensation is applied to allow the machine flux to build up. When the drive operates
between rated frequency/4 and rated frequency/2 the Rs compensation is gradually reduced to zero as the frequency increases. For the vector
21.07 Motor 2 motor rated current
Coding
Bit SP FI DE Txt VM DP ND RA NC NV PT US RW BU PS
12 1 111
Range 0 to RATED_CURRENT_MAX A
Default Drive rated current (Pr 11.32)
First motor
parameter
Pr 5.07
Update rate Background
21.08 Motor 2 motor rated full load rpm
Coding
Bit SP FI DE Txt VM DP ND RA NC NV PT US RW BU PS
111
Range 0 to 9999
Default EUR: 1500, USA 1800
First motor
parameter
Pr 5.08
Update rate Background
21.09 Motor 2 motor rated voltage
Coding
Bit SP FI DE Txt VM DP ND RA NC NV PT US RW BU PS
11 111
Range 0 to AC_VOLTAGE_SET_MAX V
Default
200V rating drive: 230V
400V rating drive: EUR: 400V, USA: 460V
First motor
parameter
Pr 5.09
Update rate 128ms
Rated slip Motor rated frequency No. of motor pole pairs Motor full load rpm 60⁄×()– Pr 21.06 Pr 21.11 2⁄()Pr 21.08 60⁄()×[]–= =
Slip compensation Rated slip Active current Rated active current⁄×=
NOTE
NOTE
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