C-28 Parameter Reference
AC30 series Variable Speed Drive
If the instantaneous braking power is greater than the Brake Rated Power parameter then this overload is accumulated. If the overload area (power
excess x time) reaches the level set in the Brake Overrating parameter then the brake switch is automatically disabled. This can then lead to an
overvoltage trip protecting the inverter.
The voltage level at which braking occurs is nominally 764V, but rises linearly to 773V as the overload area rises to the Brake Overrating limit. This
improves the brake energy sharing in a multi-brake common d.c. bus system, which can be effected by variation in the exact braking voltage level in
each inverter.
The Braking feature also provides a control signal that is used by the Slew Rate limit feature. This causes the setpoint to be temporarily frozen
whenever the brake is operating because the dc link voltage exceeds the internal comparison level. This allows the stop rate to be automatically
tuned to the characteristics of the load, motor, Drive and brake resistor.
Brake Rated Power
Voltage Level
(Brake Overating-1)
x Brake Rated Power
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