ESAB Powercut 875, Instruction Manual

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figure 5-2. screw fastening order






Two-Point Mounting Type
Temporary tightening




Final tightening




Four-Point Mounting Type
Temporary tightening 







Final tightening 







5.4 IGBt handling & replacement
Since IGBT gates are insulated from any other conducting region, care should be taken to prevent static build up, which
could possibly damage gate oxides. All IGBT modules are shipped from the factory with conductive foam contacting the
gate and emitter sense pins.
Always ground parts touching gate pins during installation. In general, standard ESD predictions application to FETs should
be followed.
Other handling precautions that should also be observed are as follows:
• Use grounded work station with grounded floors and grounded wrist straps when handling devices.
• Use a 100W resistor in series with the gate when performing curve tracer tests.
• Never install devices into systems with power connected to the system.
• Use soldering irons with grounded tips when soldering to gate terminals.
When mounting IGBT modules on a heatsink, certain precautions should be taken to prevent any damage against a sudden
torque. If a sudden torque (“one-sided tightening”) is applied at only one mounting terminal the ceramic insulation plate or
silicon chip inside the module may get damaged.
The mounting screws are to be fastened in the order shown in Figure 5-2. Also, care must be taken to achieve maximum
contact (i.e. minimum contact thermal resistance) for the best heat dissipation.
Application of a thermal pad on the contact surface improves it thermal conductivity. See Replacement Parts section for
the required pad.
A torque wrench should be used. Tighten mounting screws to 28 in-lbs; wire connecting screws to 19 in-lbs. If torque is too
heavy, the device can damage like the above “one-sided tightening”.
sectIon 5 maIntenance