Danfoss VLT Series Service Manual page 35

Section Five
PARAMETER 108
Motor Magnetization Current is the current required to maintain the magnetic field
in the motor. Magnetization Current is factory set based on the motor power
entered in parameter 103. This current value can also be found by running the
motor without anything connected to the shaft and recording the current. Data
charts in motor catalogs also contain this information.
PARAMETER 109
Start voltage is factory set based on the motor power entered in parameter 103.
In most cases the factory setting is sufficient; however, a slight increase in start
voltage may be required for high inertia loads. High current at low speeds results
in an increased voltage drop in the motor and hence the need for additional start
voltage.
If multiple motors are connected to a single unit, it is usually necessary to increase
the start voltage. Smaller motors have greater voltage drops at low frequencies
so additional start voltage is usually required.
It is also possible to have start voltage set too high and result in start-up trouble.
The best rule of thumb is to start at the factory setting and make changes in small
increments. Start and stop the unit to test the results.
PARAMETER 110 (VLT SERIES 3000 ONLY)
Start compensation is factory set based on the motor power entered in Parameter
103. In most cases the factory setting is sufficient, however, a slight increase in
start compensation may be necessary with loads requiring high starting torques
and loads with changing demands as speed increases.
If multiple motors are connected to a single unit, the start compensation must be
set to zero.
It is also possible to have start compensation set too high, resulting in excessive
current drawn at start up and motor instability.
PARAMETER 209
Current limit is factory set based on the motor size and voltage selected. Current
limit settings which are too low may result in difficulty starting or premature trips.
Current limit will automatically reset to 160% of the value entered into parameter
107 unless this would exceed the maximum allowable value.
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