Operation On An Isolated-Neutral System (It System) - Siemens SINAMICS S120 Manual

Line connection and line-side power components
3.9 Active Interface Modules internal air cooling
3.9.7

Operation on an isolated-neutral system (IT system)

IT line system
In IT systems, all live parts are isolated from ground, or one point is connected to ground
through an impedance. Housings of loads in the electrical plant or system are either
individually grounded, jointly grounded or are all connected to the system ground.
Only Line Modules without a line filter are to be operated on this system type. The emitted
interference can exceed the limit values of category C3. The Active Interface Module must
be set for operation on an IT line system.
Operating an Active Interface Module on an isolated-neutral line supply (IT line supply)
Note
When an Active Interface Module is operated on an isolated-neutral line supply (IT system),
the connecting screw for the interference suppression capacitor in the Active Interface
Module must be removed. It is located on the lower side of the component.
If it is not removed, then the insulation monitor will respond.
Removing the connecting screw to the interference-suppression capacitor eliminates the
effect of the filter with respect to ground. It nevertheless makes sense to install an Active
Interface Module because the clock frequency filter is still active and also protects other
loads on the same network from clock frequency disturbances.
Danger to life due to electric shock when the connecting screw is removed
Because of the capacitors, a hazardous voltage is present at the connecting screw for up to
5 minutes after the power supply has been switched off.
Contact with live parts can result in death or serious injury.
• Wait 5 min. after the supply has been switched off before removing the connecting
132
DANGER
screw.
Booksize Power Units
Manual, (GH2), 07/2016, 6SL3097-4AC00-0BP8