[PCB_FORUM] Re: 2KV Creepage & clearence requirements...

It's not an absolute value. Creepage is the the shortest path between 2
conductors measured along the surface of the insulation, and clearance
is the shortest path between 2 conductors measured through air. On the
FR4 data sheet there should be a CTI value this will help you establish
the creepage clearance. The CTI value will give you insulating distance
upto a breakdown voltage in standard testing. What it doesn't take into
account is humidity, contamination, corrosive chemicals or altitude in
either testing or operating environment. Obviously clearance will be
affected by the same environmental additives and complicated by the
insulation value of non-pcb conductors that are in the arc path. Also,
is the 2Kv the working voltage or is this a test voltage? It's the
working voltage that is used to calculate creepage and clearance
requirements. You should also take into account Peak and RMS voltages.
Peak is used to calculate clearance reqs, and RMS is used to calculate
creepage reqs.
If you don't have all of the information needed to make these
calculations, there is an Electical Conductor Spacing guide in IPC-2221A
that will help with rough clearance guidelines. I have used this in some
transformer applications with good success, so the values in the chart
may be on the more conservative side since our testing is high
pollution, humity, and altitude.

________________________________

From: icu-pcb-forum-bounce@xxxxxxxxxxxxx
[mailto:icu-pcb-forum-bounce@xxxxxxxxxxxxx] On Behalf Of Kesavan
Thangasamy-TLS,Chennai
Sent: Friday, March 23, 2007 5:16 PM
To: icu-pcb-forum@xxxxxxxxxxxxx
Subject: [PCB_FORUM] 2KV Creepage & clearence requirements...



Hi,

 For my new design, I am looking for information on the creepage and
clearence for 2KV. FR4 PCB is planned to use. What is the PCB spacing
needed to meet the creepage & clearence requirement? Pl helps us.....

 I would sincerely appreciate if any supporting doc is evidenced.

 

Thanks & Regards,

Kesavan.T

 

 

  

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