Michael,
Altho I don't work with UL/IEC 60745-1 ed 4 (newer than your 2003 presumably
ed 3), the scope sez that it is harmonized with IEC 60335-1 which I
reviewed. 60335 has 4 figures that show the proper touch current setup for
single phase thru 3 phase measurements. The measurement circuit is from IEC
60990 which describes touch current metering circuits that properly account
for touch current at any frequency up to 1 MHz. The Simpson 228 touch
current meter incorporates these circuits; other similar equipment is also
available. The need for expanding the measurement is to ensure proper
protection for the user at electronic controls are introduced into
equipment. The use of 0.75mArms is a traditional requirement for some
classes of equipment.
There are a number of other standards which have been using this measurement
technique for more that 20 years - eg 60950 and 61010 for commercial and
industrial equipment. There is more that can be said but this migh suffice
at this point.
Hope this brief comment helps.
:>) br, Pete
Peter E Perkins, PE
Principal Product Safety Engineer
PO Box 23427
Tigard, ORe 97281-3427
503/452-1201 fone/fax
p.perk...@ieee.org
_ _ _ _ _
Michael Nicholls
Engineer at Advanced Motion Controls
I was looking at this standard and noticed they use a different method to
measure the touch current than other standards like 60601
Do anyone know why?
The network illustrated in the standard is also vague on components and
values.
My version is 2004 so maybe it has changed?
The requirement is 0.75mA from any accessible metal surface.
Thanks for your help
-
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