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Safety instructions
Risk of death resulting from failure to observe the safety instructions and residual risks
If you fail to heed and comply with the safety instructions and residual risks in the associated
converter documentation, accidents can occur. This can result in severe injury or death.
• Observe the safety instructions in the converter documentation.
• Consider the residual risks in the risk assessment.
Danger due to insufficient training
Any operation and service involving the "Two-channel firing pulse inhibit" function must be
performed by trained qualified personnel only. The drive can start unexpectedly due to improper
operation of the function. This can result in death, serious injury or material damage.
• Carefully ensure that everyone operating or servicing the "Two-channel firing pulse inhibit"
function are adequately trained before they use the function. Training must include studying
the function and its integration into the production process. Documenting the training.
Danger due to coast down of the motor
When the "Two-channel firing pulse inhibit" function is activated while the machine is rotating,
then the motor coasts down if it has not yet come to a stop.
Incorrect use can result in death, serious injury or substantial material damage.
• Apply the appropriate protective measures to avoid danger to people resulting from the
motor coasting down after the power supply has been disconnected.
Danger of the motor jerking into motion from standstill
When certain faults occur in the Power Module, brief jerking of the motor into motion from
standstill cannot be ruled out. The simultaneous destruction (short-circuit or breakdown of
depletion layer) of 2 power thyristors in the converter may cause the drive to move briefly
depending on the number of poles that the motor has. The precondition for this brief drive
movement is that one power thyristor in the upper branch and one power thyristor offset in the
lower branch develops a short-circuit or breaks down the depletion layer. For rotary three-phase
motors, this alignment movement can be a maximum of 180° / number of pole pairs at the motor
shaft.
An alternating field is generated in the motor winding as a result of the double fault described
above where 2 power thyristors remain in the conducting state. However, this does not result in
a rotating field and continuous rotation.
The destruction of 2 power semiconductors can only occur when several power thyristors
simultaneously break down (depletion layer is broken down) or as a result of multiple
simultaneous faults in the control modules. Although these types of double faults can only occur
Two-channel firing pulse inhibit
Function Manual, 07/2021, A5E51227986A
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