Forced Bypass - Non-Faulted Cells - Siemens SINAMICS PERFECT HARMONY GH180 Function Manual

In a drive with an additional cell per phase, bypass in under ½ second will happen only on the
first cell failure per phase. If a second cell in a phase fails the control needs to wait for the motor
voltage to decay, hence the bypass time may exceed ½ second.
Note
Cell bypass limitations
Cell bypass is limited to allow no more than nine cells at a time to be in bypass. Attempting to
bypass more than nine cells will result in a bypass fault and subsequent drive fault from fast
bypass.
7.4.2

Forced Bypass - Non-faulted Cells

Forced Bypass - Non-faulted Cells
This feature adds the capability to force bypass for an individual cell by creating a pseudo cell
fault for that cell. The cell to be bypassed is designated by entering its phase and rank. Once
entered, a prompt is displayed to confirm the user's desire to bypass the cell. A "fault" is then
generated within the control software and not in the actual cell. This will display as "xx - Forced
Cell Fault" where 'xx' is the cell phase (letter) and rank (number).
Forced bypass can be used for instances when a cell may be working intermittently showing a
low DC bus, or getting spurious OOS with fast bypass disabled. Another use involves checking
the bypass contactors for proper connections or operation. This feature gives the ability to
bypass cells without opening the control cabinet.
To activate the feature, use the menu system and select the function parameter "Forced Cell
Fault" (ID 2639).
Two levels of security must be used to activate this feature.
• The Factory or Siemens authorized personnel must have access to allow it to work at both Idle
and Run drive states. Since this could cause a problem while running, it is not available for
general purpose.
• The customer has access when the drive is at Idle only and only in Level 7 security. If an
attempt is made to force bypass while the drive is running, an error message is generated to
this regard. Also, this feature is not available if the "key lock" is on.
When activated, if the selected cell is already bypassed, the user will be notified with the
message, "Cell is bypassed", and no further action will be taken. If the cell chosen is not installed,
an error message, "Cell not installed" will display, and no further action will be taken.
On the keypad version of this function if the user attempts to engage this function while there
is no medium voltage an error message, "Medium voltage low", is displayed and no further
action is taken.
On the Drive Tool version of this function the menu item selection for this function is disabled
if conditions (insufficient security, no medium voltage) are not correct for it to operate.
Once enabled, the drive control then creates a pseudo cell fault that is logged as any other fault.
A message ("Forced cell fault") is added to the event and fault logs stating that the cell fault is
forced. The event log message will also indicate whether the fault was initiated either with the
NXGPro+ Control Manual
Operating Manual, A5E50491925A
Operating the Control
7.4 Cell Bypass
183