User Manual Frequency Inverter Vector Basic
MSF – Vathauer Antriebstechnik GmbH & Co KG
Tel: +49 (0) 5231 – 63030
Am Hessentuch 6-8
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6.2. Menu point 02 – Running down ramp right (cw)
(Range from 1 to 99 in Hz/s)
Essentially, the explanations given in the section “Running-up times” also apply here.
When inappropriate short running-down ramps are selected (especially with large centrifugal
masses) over voltages in the intermediate circuit can cause a switch-off of the inverter. Since in this
state of operation, the rotating field frequency applied to the motor is slightly less than the frequency of
the motor shaft, energy will be fed back (generator operation) resulting in an inadmissible increase of
the intermediate circuit voltage in the inverter and switches off.
6.3. Menu point 03 – Running up ramp left (ccw)
(Range from 1 to 99 in Hz/s)
Description, see menupoint 01.
6.4. Menu point 04 – Running down ramp left (ccw)
(Range from 1 to 99 Hz / s)
Description, see menu point 02
6.5. Menu point 05 – Static Boost
(Range from 0 to 30 in %)
Deviating from the linear V/f characteristics, this voltage increase is specified in percent of the nominal
voltage to increase the starting torque at low rotating field frequencies.
With low rotations, the copper resistance of the stator winding strongly influences the operating
characteristics of the motor. Without a voltage correction, the breakdown torque is significantly
reduced towards low rotating field frequencies. During slow starts, it could happen that the motor does
not start due a too high breakaway torque to be obtained. By using a voltage increase - the so-called
BOOST - the starting torque is increased. The amount of the BOOST is specified in percentage of the
nominal voltage at 0 Hz. Starting at this value, the voltage is continually raised with an increasing
frequency and thus approaches the normal (linear) V/f characteristic: V/f = const. A constantly
available voltage increase is called ´static BOOST´. The range of the voltage increase extends to
about a frequency of up to of 2/3 of the kink frequency. To prevent a torque jump during the transition
of the BOOST to the V/f=constant characteristics, all characteristics of the static BOOST end at the V/f
characteristic. Good starting torques is achieved with a BOOST setting of 8%. Exaggerated high
values results in an increased motor temperature, which may destroy in the destruction of the motor
by, overheat, particularly if no separate fan is used. a high BOOST value can also cause an excessive
currant, which will likewise switch the inverter off.
