John,
Could you please expand on your last statement. What is the
difference(s) between a shunt trip breaker and a standard breaker? What
happens if a standard two pole breaker is used to interupt neutral?
Paul McCoy
"Wagner, John P (John)" <johnwag...@avaya.com>@ieee.org on 10/09/2000
09:28:08 AM
Please respond to "Wagner, John P (John)" <johnwag...@avaya.com>
Sent by: owner-emc-p...@ieee.org
To: "'brian_kunde'" <brian_ku...@leco.com>, emc-pstc
<emc-p...@majordomo.ieee.org>, "'Russell, Ray'"
<ray_russ...@gastmfg.com>
cc:
Subject: RE: Overcurrent Protection: One or Both Sides?
I take some exception to the response below.
Single phase connections between phases either on a delta or wye system do
not have a neutral connection.
There are two grounded delta systems -- corner ground where one phase is
grounded, or center tapped ground on one of the phases (commonly called
high
leg). There are also variations of the grounding scheme to allow for
impedance grounded systems where appropriate.
A standard two pole breaker os not designed, nor can it be used to
interrupt
neutral. For that, a special shunt trip braker is needed.
John P. Wagner
AVAYA Communication
11900 N. Pecos St, Room 2F58
Denver CO 80234
email: johnwag...@avaya.com
phone: 303 538-4241
fax: 303 538-5211
> ----------
> From: Russell, Ray[SMTP:ray_russ...@gastmfg.com]
> Reply To: Russell, Ray
> Sent: Monday, October 09, 2000 5:15 AM
> To: 'brian_kunde'; emc-pstc
> Subject: RE: Overcurrent Protection: One or Both Sides?
>
>
> Hi Brian,
>
> I see most of the return postings have focused on the UK, which has a
> terminated neutral system. There are several installations especially in
> the
> US, where the power could be derived from a delta, or unterminated
neutral
> system. I believe in this case, overcurrent protection is required on
both
> lines. In addition, the 2 pole circuit breaker method provides a suitable
> 2
> pole disconnect.
>
> Good Luck,
>
> Ray Russell
> ray_russ...@gastmfg.com
>
> -----Original Message-----
> From: brian_kunde [mailto:brian_ku...@leco.com]
> Sent: Friday, October 06, 2000 12:32 PM
> To: emc-pstc
> Subject: Overcurrent Protection: One or Both Sides?
>
>
>
>
> The issue of designing in Overcurrent Protection on one side or both
sides
> of
> the AC mains keeps coming up. We deal in Laboratory Equipment so the EN
> 61010-1
> is the standard we use. I'm not sure what EN60950 would say on the
> subject.
>
> The only area I have found that deals with this question is a NOTE in
> section
> 9.6 of EN61010-1 which says, "Overcurrent protection devices (e.g. fuses)
> should
> preferably be fitted in all supply conductors."
>
> This seems "GRAY" to me and I get beat up on it all the time. I feel
that
> overcurrent protection should be on all current carrying conductors.
With
> a
> 230V~ product you never know where in the world the product will be
> shipped,
> if
> the AC Main has a grounded neutral, or if the receptacle is polarized.
> So,
> I
> feel you never know for sure which line or if both lines will be "HOT" in
> reference to Earth ground.
>
> If my thinking is correct, shouldn't ALL 230V~ products have overcurrent
> protection on both sides of the line? I would think so, but I see
> products
> everyday that only have ONE side of the line fused. My superiors feel
> that
> if
> others can get away with it, why can't we. Why add the extra cost of
> double
> pole breakers or double fuse holders if it is not necessary?
>
> Am I being too cautious or do I have a point?
>
> Thank you for your support and advice.
>
> Brian Kunde
> LECO Corp.
>
>
>
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