What is "stray capacitance" ?
-Original Message-
From: Rich Nute [mailto:ri...@sdd.hp.com]
Sent: Monday, July 08, 2002 3:58 PM
To: Product Safety Technical Committee
Subject: Re: TOUCH CURRENT LIMIT
UL reasoned that if 0.5 mA arises from both real and stray capacitance,
I think that is correct - but it went from IEC 380 through IEC 435 to IEC
950
I should have a copy of the UL478 and CSA..220 standards that we used for
ITE at the time - from memory I cannot remember what they said but if I find
them I will post their requirements.
Best regards
Gregg
Rich Nute said : -
For grounded (Class I) equipment for the home, the UL leakage current
is 0.5 mA. (This is NOT a 60950 limit.)
UL reasoned that if 0.5 mA arises from both real and stray capacitance,
then, for double-insulated (Class II) equipment, the current should be
one-half of 0.5 mA beca
Hi Xing Weibing:
> We can read from table 5A of IEC60950:1999:
>
> Touch current limit for accessible parts and circuits not connected
>
> to protective earth: 0.25 mA
>
> question 1 : How does it (0.25mA) come from and what it is based on?
For grounded (Class I) equipment for the home,
---
From: "Ron Pickard"
To:
Cc:
Sent: Tuesday, June 25, 2002 11:50 PM
Subject: Re: TOUCH CURRENT LIMIT
>
>
> Hi Xing,
>
> Find my comments below marked with ***.
>
> Your email stated:
> >Our test lab receive a CB TEST REPORT FOR NATIONAL RECOGNIZATION
Hi Xing,
Find my comments below marked with ***.
Your email stated:
>Our test lab receive a CB TEST REPORT FOR NATIONAL RECOGNIZATION,
>the EUT is a class II ac adapter having a bridging capacitor (4700pF)across
>the reinforced
insulation
>The touch current measured by CB is 0.17mA(4700pF decl
uesday, June 25, 2002 11:57 AM
To: Peter Merguerian
Cc: emc-p...@majordomo.ieee.org
Subject: Re: TOUCH CURRENT LIMIT
Hi Mr. Peter:
Our test lab receive a CB TEST REPORT FOR NATIONAL RECOGNIZATION,
the EUT is a class II ac adapter having a bridging capacitor (4700pF)across
the reinforced insu
o.ieee.org
Sent: Tuesday, June 25, 2002 6:38 PM
Subject: RE: TOUCH CURRENT LIMIT
Xing,
Yes, 0.25mA is very strict for 950. However, I can assure you that depeding
on the test lab and uncertainty of the test equipment, you will obtain slightly
different results.
This e-mail message m
[mailto:xin...@cesi.ac.cn]
Sent: Tuesday, June 25, 2002 11:13 AM
To: Robert Johnson; Peter Merguerian
Cc: emc-p...@majordomo.ieee.org
Subject: Re: TOUCH CURRENT LIMIT
Dear SIRS:
Thanks for your e-mail
A further question for touch current:
Is it (0.25mA) strict for Class II equipment ?
0.28mA r
: Peter Merguerian
To: 'xingwb' ; emc-p...@majordomo.ieee.org
Cc: Ilan Cohen ; Michael G ; Shmuel Gnatt ; Sima Beloborodov ; Valery
Rodionov
Sent: Monday, June 24, 2002 9:00 PM
Subject: RE: TOUCH CURRENT LIMIT
Xing Hello!
ake a look at IEC 60990, "Methods of measu
The history is lost in committee activities from years ago, but I can
provide my own thoughts.
The limit for accessible parts on circuits not connected to protective
earth is set below the threshold of sensation, since that current is
likely to pass through the user in normal use if he touches the
Xing Hello!
Take a look at IEC 60990, "Methods of measurement of touch current and
protective conductor current". The limits in IEC 60 950 are based on this
particular standard.
Best Regards
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