Description of choice:
To be set as a percentage value of the maximum DC brake
voltage, which depends on the motor.
133
Start voltage
Value:
0.00-100.00 V
Depends on unit
Function:
A higher start torque can be obtained by increasing the
start voltage. Small motors (< 1.0 kW) normally require a
high start voltage.
Illustration 4.5 Start Voltage and Torque
Description of choice:
The factory setting is suitable for must applications. The
value may need to be increases gradually for high torque
applications.
WARNING
If the use of start voltage is exaggerated, this may lead
to overenergising and overheating of the motor, and the
frequency converter may cut out.
134
Load compensation
Value:
0.0-300.0%
100.0%
Function:
Use this parameter to set the load characteristic. By
increasing the load compensation, the motor is given an
extra voltage and frequency supplement at increasing
loads. This is used e.g. in motors/applications in which
there is a big difference between the full-load current and
idle-load current of the motor.
Description of choice:
If the factory setting is not adequate, set load compen-
sation to enable the motor to start at the given load.
WARNING
If this value is set too high, the frequency converter may
cut out because of overcurrent.
WARNING
Set to 0% if the frequency converter is connected with
synchronous and parallel-coupled motors and in the case
of quick load changes. Too high load compensation may
lead to instability.
135
U/f-ratio
Value:
0.00-20.00 at Hz
Depends on unit
Function:
This parameter enables a shift in the ratio between output
voltage (U) and output frequency (f) linearly, to ensure
correct energising of the motor and thus optimum
dynamics, accuracy and efficiency. The U/f-ratio only affects
the voltage characteristic if a selection has been made of
[1] Constant torque parameter 101 Torque characteristic
.
Description of choice:
The U/f-ratio is only to be changed if it is not possible to
set the correct motor data in
parameters 102-109
. The
value programmed in the factory settings is based on idle
operation.
136
Slip compensation
Value:
-500 - +500% of rated slip compensation
100%
Function:
Slip compensation is calculated automatically, on the basis
of data as the rated motor speed n
M,N
. In this parameter,
the slip compensation can be fine-tuned, thereby compen-
sating for tolerances on the value for n
M,N
. Slip
compensation is only active if a selection has been made
of
[0] Speedregulation, open loop
in
parameter 100 Configu-
ration
and
[1] Constant torque
in
parameter 101 Torque
characteristic
.
Description of choice:
Enter a % value.
137
DC hold voltage
Value:
0-100% of max. DC hold voltage
0%
Function:
This parameter is used to keep the motor (holding torque)
at start/stop.
Description of choice:
This parameter can only be used if a selection has been
made of
DC hold
in
parameter 121 Start function
or
122
Function at stop
. To be set as a percentage value of the
max. DC hold voltage, which depends on the choice of
motor.
Programming
Design Guide
74
Danfoss A/S © Rev. May/2014 All rights reserved.
MG27E402
4
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