Danfoss VLT AutomationDrive FC 301 Instruction Manual page 30

Commissioning
7. 1-40 Back EMF at 1000 RPM
Enter line-to-line back EMF of PM Motor at 1000
RPM mechanical speed (RMS value). Back EMF is
the voltage generated by a PM motor when no
drive is connected and the shaft is turned
externally. Back EMF is normally specified for
nominal motor speed or for 1,000 RPM measured
between two lines. If the value is not available for
a motor speed of 1000 RPM, calculate the correct
value as follows: If back EMF is, e.g., 320 V at
5 5
1800 RPM, it can be calculated at 1000 RPM as
follows: Back EMF = (Voltage / RPM)*1000 =
(320/1800)*1000 = 178. This is the value that
must be programmed for 1-40 Back EMF at 1000
RPM.
Test Motor Operation
1. Start the motor at low speed (100 to 200 RPM). If
the motor does not turn, check installation,
general programming and motor data.
2. Check if start function in 1-70 PM Start Mode fits
the application requirements.
Rotor detection
This function is the recommended choice for applications
where the motor starts from standstill, e.g., pumps or
conveyors. On some motors, an acoustic sound is heard
when the impulse is sent out. This does not harm the
motor.
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Instruction Manual
Parking
This function is the recommended choice for applications
where the motor is rotating at slow speed, e.g.,
windmilling in fan applications. 2-06 Parking Current and
2-07 Parking Time can be adjusted. Increase the factory
setting of these parameters for applications with high
inertia.
Start the motor at nominal speed. If the application does
not run well, check the VVC
dations for different applications can be seen in Table 5.6.
Application
Low inertia applications
I
Low inertia applications
50>I
High inertia applications
I
High load at low speed
<30% (rated speed)
If the motor starts oscillating at a certain speed, increase
1-14 Damping Gain. Increase the value in small steps.
Depending on the motor, a good value for this parameter
can be 10% or 100% higher than the default value.
Starting torque can be adjusted in 1-66 Min. Current at Low
Speed. 100% provides nominal torque as starting torque.
Danfoss A/S © Rev. 2014-02-10 All rights reserved.
plus
Settings
1-17 Voltage filter time const. to be
/I <5 increased by factor 5 to 10
Load Motor
1-14 Damping Gain should be
reduced
1-66 Min. Current at Low Speed
should be reduced (<100%)
Keep calculated values
/I >5
Load Motor
1-14 Damping Gain, 1-15 Low Speed
/I > 50 Filter Time Const. and 1-16 High
Load Motor
Speed Filter Time Const. should be
increased
1-17 Voltage filter time const. should
be increased
1-66 Min. Current at Low Speed
should be increased (>100% for a
prolonged time can overheat the
motor)
Table 5.6 Recommendations for Different Applications
PM settings. Recommen-
MG33AN22