When the speed controller power supply is switched on the power units, as well as a certain number of control
components are connected to the mains supply, contact with these parts is extremely dangerous
After disconnecting the ALTIVAR from the mains voltage, wait 5 minutes before carrying out any operation Inside the
controller This period corresponds to the time constant for the discharge of the capacitors The + and - terminals (or PA-
PB for the controllers from 37 to 90 kW) are also connected to the potential of the capacitors.
During operation, the motor can be stopped by canceling the run command or the speed reference, while the speed
controller remains energized If restarting needs to be prevented for personnel safety reasons, this electronic interlock is
inadequate Provision must be made for the disconnection of the power circuit.
The speed controller includes safety devices which, In the event of a fault, can cause the tripping of the controller, and
hence stop the motor The motor itself can also be subject to stoppage by mechanical jamming, voltage fluctuations and
power supply failures in particular.
The clearance of the fault causing the stoppage can Initiate a restart Involving a hazard for certain types of machines or
Installations especially those which must conform to specific safety regulations.
It is important that in such cases the user should take appropriate steps to prevent such restarting For example. by the
use of an underspeed detector, causing the disconnection of the speed controller power supply In the event of a non-
programmed motor stoppage.
As a general rule, the speed controller power supply must always be switched off before carrying out any operation on
either the electrical or the mechanical parts of the installation or the machine.
(page 3 - 151)