Ride Through - Siemens 6SR41 series Product User Manual

5.8

Ride Through

For NXG control, "Ride Through" occurs when the medium voltage input to the drive
decreases below ~65% of nominal. During this condition, the control forces the drive to go
into regeneration, thereby absorbing power from the rotating motor and maintaining the
power cell stored energy. Such operation is maintained as long as medium voltage is absent
(or below 65%) and all cells are functioning. Typically, with very large inertia loads such as
fans, operation with no medium voltage is achievable for periods in excess of 5 cycles. If a
cell reports a fault when the drive is operating in "Ride Through," the drive will trip on a "No
Medium Voltage Fault."
The eighteen-pulse nine cell GenIV drive was factory-tested at SIEMENS for input line
voltage immunity. The drive was shown to have a ride through capability of 5 cycles or more
(line voltage was removed and then re-applied 7.5 cycles later).
*
Figure 5-32
Note
Depending upon motor inertia, ride through in excess of 5 cycles is possible with the addition
of a UPS for the auxiliary controls.
Product User Manual
Operating Instructions, Version AE 12/2009, A5E01454341C
Results shown for a 4160 V input 1100 Hp drive loaded at 515 kW output prior to the input
medium voltage
removal.
Five Cycle Ride Through Capability
Product Description
5.8 Ride Through
103