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 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.
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
plus
PM settings. Recommen-
dations for different applications can be seen in Table 5.6.
Application Settings
Low inertia applications
I
Load
/I
Motor
<5
1-17 Voltage Filter Time Const. to be
increased by factor 5 to 10
1-14 Damping Gain should be
reduced
1-66 Min. Current at Low Speed
should be reduced (<100%)
Low inertia applications
50>I
Load
/I
Motor
>5
Keep calculated values
High inertia applications
I
Load
/I
Motor
> 50
1-14 Damping Gain, 1-15 Low Speed
Filter Time Const. and 1-16 High
Speed Filter Time Const. should be
increased
High load at low speed
<30% (rated speed)
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
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.
5.4.5
Automatic Energy Optimization (AEO)
NOTICE!
AEO is not relevant for permanent magnet motors.
Automatic Energy Optimization (AEO) is a procedure that
minimizes voltage to the motor, reducing energy
consumption, heat, and noise.
To activate AEO, set parameter 1-03 Torque Characteristics
to [2] Auto Energy Optim. CT or [3] Auto Energy Optim. VT.
Commissioning
Instruction Manual
MG16E322 Danfoss A/S © Rev. 2014-04-10 All rights reserved. 29
5 5
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