Flux Reduction - Siemens SINUMERIK 840D sl Ctrl-Energy System Manual

Flux reduction

In the drive parameters (p1581 [0..n]), the rated magnetization for induction motors – which is
normally 100% – can be permanently reduced. This includes the switching times for reducing
and building up the flux (r1578, r1579[0...n]).
In this case, not only can the magnetizing losses in the motors be reduced at standstill, but
also during operations that only require a lower power.
Optimization criterion
Under no-load conditions, the percentage value of the rated magnetization is reduced in steps
of between 5-10% to just above a value where the no-load behavior starts to become uneven.
From this limit value onwards, rough operating behavior can be heard as a result of the
significantly fluctuating active current.
It makes sense to monitor the current characteristic and this transition point using a trace
function.
Options for use
You have various options to specifically use this.
● Permanently set the actual parameter set p1581 [0] to the determined value <100%.
Taking into consideration the time constants, the flux is automatically reduced if the
instantaneous active power permits this. If more active power is demanded, then the flex
automatically increases back up to 100% with the corresponding time constant. This does
not have a negative impact on the process.
● Preselecting various parameter sets
If load changes are to be expected in a time shorter than the time constant (e.g. for an
interrupted roughing cut with facing head milling tools), it may be more favorable for the
process if the flux is permanently controlled by pre-selecting various parameter sets by
knowing the machining to be expected or the tool involved.
Example ((see the interface signals at the spindle DB31-61.DBB21))
Bit0: = 0:
p1581 [0] = 100%;
p1578 [0] and p1579 [0] = factory setting, e.g. for an interrupted cut
Bit0: = 1:
p1581 [1] < 100%;
p1578 [1], p1579 [1], adapted for partial load or no load
Ctrl-Energy
System Manual, 01/2015, 6FC5397-0EP40-5BA2
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