Joe,
Thanks for this, good information. I will check out that Bourns part.
I have an application for a communications channel over pairs of HV
wires. Similar to Power Over Ethernet for running a device, but
definitely not the same. I've seen that 1500V rating as well, which is
a 60 second dielectric test. Looks great for a marketing brochure. If
you rearrange the algebra for "typical" hipot calculation you get
(1500-1000)/2 or a 250 VAC working voltage, not so great and certainly
not UL listed. I could do a fiber optic link but this would be a major
change to the product design in order to get transceivers and isolated
power on the HV side. In any case this is driven by a UL safety
standard and I have virtually no hope of fining a UL listed device so we
will likely have to go through all the component qualifications for the
application.
My last option may be to design a transformer from scratch with fully
insulated windings on primary and secondary using UL style wire
appropriate for the job. If that is still not enough, encapsulation
could be an option.
All the best, Doug
On 11/3/2014 11:44 AM, Joe Randolph wrote:
Hi Doug:
That’s an unusual set of requirements. Is this a conventional
Ethernet transceiver application for twisted-pair, or something different?
Any Ethernet transformer that complies with the IEEE 802.3 standard
will be rated for 1500 VRMS isolation and should easily meet your 1200
VDC requirement for primary-to-secondary isolation. However, this is
just a voltage test and there are no corresponding guarantees for
internal creepage, clearance, or distance through solid insulation.
So, specifying only the external creepage distance may not be
adequate, depending on what particular requirements you are trying to
meet.
That being said, if your 5.1 mm creepage distance requirement applies
primary-to-secondary, most Ethernet transformers put all the primary
pins on one side of the package, and all the secondary pins on the
other side of the package. For primary-to-secondary creepage
distance, there is no need to be concerned with the separation of
adjacent pins on the same side of the package. You should be able to
achieve your 5.1 mm goal with the side-to-side separation of most
Ethernet transformers.
One particular Ethernet transformer that was explicitly designed for
high primary-to-secondary isolation (5000 VRMS) is the Bourns
SM51589PEL. The external primary-to-secondary creepage distance of
the package is approximately 10 mm.
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
[email protected] <mailto:[email protected]>
http://www.randolph-telecom.com
*From:*Doug Powell [mailto:[email protected]]
*Sent:* Monday, November 03, 2014 12:22 PM
*To:* [email protected]
*Subject:* [PSES] Network Isolation Transformer
All,
I am searching for an ethernet isolation transformer that has a PRI to
SEC safety isolation rating of at least 1,200 VDC. On top of that a
surface mount version is preferred but not essential. I am able to
identify several with a manufacture rating high enough but pad-to-pad
creepage distance is only about 1.5 mm on the surface of a PCB and I
need at least 5.1 mm.
I appreciate hearing about any sources you might be able to identify
for me.
Doug
--
Douglas E Powell
[email protected] <mailto:[email protected]>
Skype: doug.powell52
http://www.linkedin.com/in/dougp01
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Thank you, ~Doug
--
Douglas E Powell
[email protected]
Skype: doug.powell52
http://www.linkedin.com/in/dougp01
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http://product-compliance.oc.ieee.org/ can be used for graphics (in well-used
formats), large files, etc.
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