Santerno DCREG2 Series User Manual page 105

DCREG2
15P0059B3
DCREG4
USER MANUAL
The value set in par. C016 (IfldMinLim) represents the min. limit for the field current provided that the drive
is running. We recommend that this limit be never set below the min. current that the regulator will actually
retrieve. Leave a 25% safety margin.
Field value 1.8A at the max. speed is not to be set in any parameters, as it will automatically be
retrieved by the control loop of the back-electromotive force.
Always try to set in par. C016 the min. limit, depending on the field current at the max. speed, as
sometimes the speed of rotation may reach very high levels, which may damage the mechanical parts.
For example, this may occur if the max. speed has been set at a very high level (a wrong terminal has
been connected in case of a tacho feedback, or the setting of transduction constant C072 or CO74 is
wrong), or the motor could be accelerated by an external torque.
In both cases, the field regulator will keep decreasing the field current in order to keep the back-
electromotive force constant and Alarm A010 (Armature Overvoltage) will not trip: that's why C016 min.
value is to be set. If an additional field current decrease is inhibited, Alarm A023 (Ifld Underlimited) trips
and the drive is locked.
The dynamic regulation of the field current in field weakening mode is possible only in tacho or enP/Nr
feedback mode, not in armature feedback mode. If a speed feedback failure occurs, the automatic switch
may be programmed towards the armature feedback by setting par. C155 to 2:Switch to Varm.
In order to keep the speed of rotation approx. constant with the same reference, the max. armature
voltage is to be programmed in par. P011. Always referring to the motor chosen in the example above:
P011 (VarmMax) = C012 (VarmNom) = 400V
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