Monitoring
Parameter manual b maXX BM5800
Document No.: 5.16029.03 Baumüller Nürnberg GmbH
720
of 814
3.11
Speed variable I2t overload monitoring of synchronous machines
In general higher current (as rated current) can be applied at synchronous machines in
the speed range lower than the rated speed due to the reduced iron losses. In contrast,
in general the maximum continuous current sinks if the speed is greater than the rated
speed due to increased iron losses.
Figure 189: Typical continuous current limit identification of synchronous motors
The l
2
t model speed dependence is provided by two solutions selectable via the param-
eter Z6.43–. Thereby must be considered that each method requires valid data from the
electronic type plate. If these values are not available the parameter Z6.43– will not ac-
cept the method.
Continuous current with current support points and interpolation
This option (activatable by speed-dependent modes Z6.43– bits 0 to 2, value = 1) re-
quires that support points are provided for the continuous current limit characteristic (S1
characteristic or S1 current limit curve) over the speed curve so that the calculation of an
interpolated current limit curve can be made. By means of the interpolated current limit
curve and the effective speed the maximum permissible continuous current can be cal
-
culated. The number of current supporting points includes 11 points whereat the first point
should be equal to the standstill current (
Z107.10–). The 10 current values remaining are
entered by a fixed delta of the maximum mechanical speed (Z107.26–) divided by 10.
The values of the current support points can be entered by the single elements of the pa-
rameters Z107.72– (107.72[0] to 107.72[10]) manually or can be called up and loaded in
case of Baumüller machines as a pre-manufactured set via the motor data base in
ProDrive. In case there is no complete set available or at least one supporting point is ze
-
ro, this option cannot be activated.
5000_0358_rev01.cdr
0
0
Motor current
Motor speed
Nominal speed
107.7
Nominal
current
107.9
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