-- 2 0 --
cdte1de1
AP01:6 Gate pulses from AP01
IGBT drivers, symmetry monitoring and symmetry control
The IGBT drivers, symmetry monitoring and symmetry control employ opto
couplers with an isolation voltage of 5kV.
When there is no signal from the symmetry circuits on AP02, IC81:3 and IC83:3
are connected to 0 V.
When signal OUT1 is low, gate B2 of IGBT Q05 is negative, i.e. Q05 is off.
When signal OUT1 is high, gate B2 of IGBT Q05 is positive, i.e. Q05 is
conducting.
OUT2 and gate B1 of IGBT Q05 oper ate in the same way as the circuits above.
If there is a signal from the symmetry monitoring on circuit board AP02, either
gate B1 or gate B2 is locked, depending on the polarity, until the symmetry fault
is gone. This action does not stop the welding.
For more information about symmetry monitoring, see page 27.
Circuit boards AP11 and AP12 protect AP01 if there is a short circuit in the
IGBT module Q05. If the IGBT module is faulty, check the fuses on AP11 and
AP12: see instructions on page 55. Check the gate pulses too, using the
instructions on the next page.
Test instruction for the IGBT module is on page 61.
NEVER check the gatepulses when the machine is connected to the mains
in the normal way.
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