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Section 8.3 Propulsion Converters
Propulsion Converters are very large
variable frequency drives . Recall from
Subsection 4.4.5 that VFDs are electronic devices that take fixed frequency AC and convert it to variable-voltage, variable-frequency AC. A VFD can drive an induction motor at any combination of speed and torque within the motor’s operating range.
The ship’s propulsion converters convert the fixed 6,600 V, 60 Hz AC from the High Voltage Main Switchboard (HVMSB) into a variable voltage and frequency which is used to drive the two electric propulsion motors at any speed commanded by the bridge.
Table 8.3.1. Frequency Converter Specifications
Manufacturer
General Electric
Model
MV7306 DFE 12P
Rated output power
4.75 MW
Input voltage
1,850 V
Output voltage
variable 0 – 3,150 V
Output current
1,035 A maximum
Supply frequency
60H
Output frequency
variable 15 – 90 Hz
