Cell Bypass Option; The Cell Control System; The Master Control System - Siemens PERFECT HARMONY GENIII/E Series User Manual

Air cooled

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Hardware Components

Perfect Harmony GENIII/e User's Manual

2.1.4

Cell Bypass Option

As an option, each cell in the system can be equipped with a bypass contactor. This contactor will be automatically

energized by the VFD master control if the associated cell malfunctions. Once the contactor is energized, the

damaged cell is no longer electrically part of the system, which allows the VFD to resume operation.

Any time a cell malfunctions and is bypassed, the control automatically compensates (shifts the neutral point) so that

the motor voltage stays balanced. To compensate for the loss in voltage, systems with up to 5 cells per phase can be

equipped (as an option) with an extra cell per phase. The 3 spare cells would then compensate for the loss in voltage.

If spare cells are not installed, then the VFD will operate at a slightly lower voltage, but will still provide full rated

current.

The cell bypass system includes a bypass contactor per cell, a contactor control board (installed inside the cell

cabinet), and a fiber optic link between the master control system and the contactor control board.

All Perfect Harmony cells are controlled in the same manner. The Cell Control/Gate Driver Boards reside within the

output cell and accept all communication from the Digital Modulator in the Control Cabinet via fiber-optic links.

Control power for all cell boards is supplied from a switch mode power supply that is resident on the Cell Control/

Gate Driver Board.

Figure 2-11: Typical Connection Diagram for an 18 Cell 6.6 kV System

The Master Control located within the Control Cabinet consists of a chassis and several control boards refer to Figure

2-12. The chassis is supplied power by a stand alone power supply. The heart of the control is the Microprocessor

board. This board is the master of the backplane bus, and controls the operation of each board in the system.

Contained on the Microprocessor Board is Flash Disk, which may be removed from the Microprocessor Board if, for

any reason, the Microprocessor Board would need to be replaced. The Flash Disk contains all the specific parameter

s s s s

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A1A19000405A: Version 1.3

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