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1400v TO-247 creepage distances
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jusanother:
What am I missing here. Taking this transistor as an example IRG7PK35UD1PbF. A 1400v IGBT.

The creepage distance between adjacent pins on a TO-247 is ~ 2.93mm.

If we use the attached creepage chart (Creepage.jpg) and interpolate between 1250v (4.2mm) and 1600v (5.6mm) we get 4.8mm minimum creepage distance best case.

So how the hell do you use this IGBT at or near it's rated voltage !?

Is it a case of (as per the second creepage chart Ventec Creepages.png) "For glass, mica, ceramic or similar materials it is permitted to use minimum CREEPAGE DISTANCES equal to the applicable CLEARANCES." ?

Is the TO-247 case material classed as a "similar material" ?
This exemption only exists for Pollution Degree 1, so I take it Pollution Degree 1 is mandatory for devices like this at 1400v ?

wraper:

--- Quote from: jusanother on June 10, 2019, 06:40:29 pm ---If we use the attached creepage chart (Creepage.jpg) and interpolate between 1250v (4.2mm) and 1600v (5.6mm) we get 4.8mm minimum creepage distance best case.

--- End quote ---
At least second chart is completely irrelevant to your question. It's for isolation safety requirements between high and low voltage parts. Nothing to do with distance between transistor legs.
wraper:
First chart is for RMS voltage, not peak voltage. As of how to do this, form middle leg to increase distance from two others and make cutout in PCB between collector and 2 other pins.
jusanother:
I understand what you mean with respect to making a tripod leg configuration but this doesn't alter the distance between the pins as they enter the device. Why is 2.9mm at the device acceptable ?
rsjsouza:

--- Quote from: jusanother on June 10, 2019, 07:31:35 pm ---I understand what you mean with respect to making a tripod leg configuration but this doesn't alter the distance between the pins as they enter the device. Why is 2.9mm at the device acceptable ?

--- End quote ---
I am not sure if the tables you show are relative to "air" or a PCB track creepage.

A general rule of thumb is 30kV/cm or 3kV/mm, giving enough margin for the related voltages.
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