Issue 08/2013
Page 24
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iMAPLA system description
Function description
Magnetisation is completed a lot earlier and the lifting magnet reaches its
maximum tension force much earlier. Once the saved current value has been
reached, the voltage is reduced to the rated value. As a result, the current in
the lifting magnet remains constant until the load is released.
Ö
Fig. 2, Characteristic curve, “lifting”, page 24
Magnetic force
(corresponds to the
flow of current)
Quick magnetisation
with impulse excitation
Normal magnetisation
without impulse excitation
Lifting
Time
Fig. 2 Characteristic curve, “lifting”
4.4.2
Release load (switch off lifting magnet)
During standard demagnetisation, the magnetic current also falls slowly, like
an exponential function. The residual magnetism which persists for a long
time means the lifting magnet needs a relatively long time to release the
entire load.
Ö
Fig. 3, Characteristic curve “release”, page 25
To accelerate the demagnetisation, the
i
MAPLA system uses an automatic
demagnetisation process with countervoltage and sequence pulsation.
This method also uses the reference current measured before starting for the
first time.
