As a quite new member of this group, I hope the following info can be
valuable:
Acc. to IEC950+A1/A2/A3 or EN60950+A1/A2/A3, clause 6.3.3:
Insulation must comply with the requirements for supplementary
insulation for a primary circuit. Suppose a pollution degree 2 and a
material group III and You get:
clearance : 2.0mm
creepage : 2.5mm
distance through insulation : 0.4mm
dielectric strength test : 1500 volt RMS
Acc. to IEC950+A1/A2/A3/A4, clause 6.3.3:
Insulation must comply with the following requirements:
dielectric strength test : 1500 volt RMS (acc. to clause 6.4.2.2)
no clearance, creepage or whatever is specified anymore; remember there
is an editorial mistake on Figure 17 of 950 ("Supplementary Insulation"
must be deleted).
As I heard recently, and it is probabaly related to the third edition of
950, the test of clause 6.3.3 will be 1500 volt for 220 volt systems and
1000 volt for 110 volt systems. This clarification is necessary because
clause 6.3.3 doesn't tell which voltage of 6.4.4.2 must be used (1kV or
1.5kV).
I also want to make clear that EN60950/A1/A2/A3/A4 does not exist at the
moment and "Special National Conditions" or "A-deviations" are not taken
into account in my former explanation.
Kind regards,
______________________
Kris Carpentier - GQ4 \ /
_______________________________________________\ /___
\ /
Product Safety Lab ALCATEL TELECOM
Tel: 32-3-240 79 86 Francis Wellesplein 1
Fax: 32-3-240 99 33 2018 Antwerpen, Belgium
____________________________________________________\ /________
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Internet : [email protected] \ /
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o=alcatel,s=Carpentier,g=Kristiaan \/
~In a message dated 96-09-25, Ron Pickard writes:
~
~>I have been asked to post a request to identify a telecommunications
relay
~>which has a published Dielectric Strength (Hi Pot) of 1500 vac, ( or
2121
~>vdc) between open contacts which is sometimes called
"Contact-to-Contact
~>Dielectric Rating".
~>
~>This relay has been reportedly difficult to find, and if found could
remove
~>costly additions for isolation of a serial port, to meet EN
41003/EN60950.
~>
~
~Ron:
~
~Are you SURE that a 1500 volt dielectric strength test will be
sufficient for
~EN 41003 and EN 60950? If you are trying to meet the requirements of
~supplementary insulation (clause 4.4.2 in EN 41003, and 6.3.3 in EN
60950), I
~think that creepage and clearance distance requirements will also
apply. If
~you have information to the contrary, I would like to hear about it.
~
~A few years ago, the only relay I could find that met the requirements
for
~supplementary insulation between open contacts was the Omron G5H-2.
This
~part actually has reinforced insulation between open contacts! Nice
part,
~but very expensive.
~
~I would be interested to hear about any other relays that might be
suitable.
~
~
~
~Joe Randolph
~Telecom Design Consultant
~Randolph telecom, Inc.
