Bypass Control - Siemens SINAMICS PERFECT HARMONY GH180 Function Manual

The modulator is designed to perform the following additional actions:
• The modulator can disable all drive cells in a fast manner. There are a maximum of two cell
transmission periods to protect the cells.
• The modulator directly (through programmed logic) disables the operation of the cells in the
following cases:
– a (fiber optic) link fault which is generated if the cell does not respond properly before the
– an IOC (Instantanious Over Current).
– a PSFail (Power Supply Fail).
– a HE PSFail (Hall Effect Power Supplies Fail).
– any bypass fault is detected.
– a hardware inhibit signal (CR3) is present.
If the drive does not update the modulator in four fast loop cycles, the protection in the
modulator disables the cells. This protection is the modulator watchdog which is enabled
automatically anytime the drive enable is true allowing the transistors in the cells to gate or turn
on.
5.2.5

Bypass Control

When the bypass option is installed, the cellular configuration of the power section ensures that,
if a critical component on a cell fails, the cell can be bypassed at the output of the cell and the
drive will continue to run at near full capability. This is done through output contactors for each
cell.
The modulator controls the activation of the bypass contactors via a fiber optic link to the
medium voltage (MV) bypass board. The MV bypass board contains driving and sensing circuitry
to interface to the cell-based output contactors. Via this interface, if the control trips on a cell
fault, it isolates the faulted cell, compensates for the neutral-shift to equalize the three output
phase voltages, and re-enables the drive output after a sub-second delay depending on
contactor travel time. This fast bypass feature provides maximum availability by making the cell
trip as transparent as possible to the system process.
Electric Shock Hazard
Risk of death or serious injury.
The medium voltage bypass board is located in the high voltage section of the drive and is at
high voltage potential.
Components in this area must only be accessed by qualified Siemens personnel.
NXGPro+ Control Manual
Operating Manual, A5E50491925A
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Hardware User Interface Description
5.2 Non-user Accessible Interfaces
67