You are referring to a Shunt Trip circuit breaker. These circuit breakers
have an additional mechanism that will trip the actuator. The shunt trip
mechanism is activated by a switch closure. It does not degrade the normal
trip mechanism or contacts of the circuit breaker. The shunt trip circuit
breakers are a preferred method for remotely triggering a circuit breaker.
It is much safer than shorting the phases.
The red buttons are commonly known as Emergency Power Off (EPO) buttons and
they are required by many electrical codes for specified applications.
They are typically used where there are life safety issues. It allows you
to shut down all of the equipment in an area making it safe for emergency
responders. If you were a fireman, would you want to enter a room with
hazardous voltages and hazardous moving machinery?
Many people hate the EPO buttons because they provide a single point of
failure. An accidental activation of the EPO can shut down your equipment,
which can be expensive for large manufacturing facilities or computer data
centers. In these cases, you want an EPO that is designed to be easy to
activate in an emergency and hard to activate by accident. Manufacturing
locations typically use a version that shuts down just one piece of
machinery, known as an Emergency Stop, or E-Stop button. These buttons
need to be located such that the operator can easily reach them, especially
if the operator becomes entangled in the machinery.
Ted Eckert
American Power Conversion Corporation
The items contained in this e-mail reflect the personal opinions of the
writer and are only provided for the assistance of the reader. The writer
is not speaking in an official capacity for APC nor representing APC's
official position on any matter.
"Kunde, Brian"
<brian_kunde@leco
tc.com> To
Sent by: <EMC-PSTC@listserv.ieee.org>
emc-p...@ieee.org cc
Subject
10/05/2006 02:46 RE: shorting the mains prohibited -
PM Help
Instead of shorting the AC Mains, have you considered using a breaker
with a trip coil? We used one in a product where as a safety measure, if
something bad happened, we wanted to cut power to the entire machine.
All we had to do is short out a set of contacts which powered up the
trip coil to trip the mains breaker and all power was shut down.
Going a different way, in my shop class in High School there were these
boxes with big red buttons hanging from cords from the ceiling all over
the shop. If you pushed any one of the red buttons, the power to the
entire shop would go off shutting down all the machines. Someone said
that when you pushed the red buttons, that it shorted out the AC and
popped the breaker for the entire room. Is that really how that was
done?
Yet another story from my past. I know an electrician who if he is
going to work on a receptacle, he just takes a piece of wire and shoves
it in the receptacle to deliberately pop the circuit breaker. He says it
is faster than switching the breakers off and on one at a time till you
find the right one. That can't be good for the breaker, right?
The other Brian.
From: emc-p...@ieee.org [mailto:emc-p...@ieee.org] On Behalf Of Don Gies
Sent: Thursday, October 05, 2006 3:17 PM
To: gmccl...@lexmark.com; EMC-PSTC@listserv.ieee.org
Subject: RE: shorting the mains prohibited - Help
Gregory,
You should recommend thermal overtemp cutouts in each power lead (if AC
mains) that open upon overtemp rather than closing upon overtemp, with
reference to IEC 60950-1, Clause 4.3.7 (Heating elements in earthed
equipment).
Shorting the mains is probably going to annoy someone, if not your
safety certification engineer.
We once did have a small dc secondary heater circuit with an overtemp
device that closed upon overtemp. Doing so shorted out the dc supply,
thereby opening a 7 A fuse in front of the overtemp device. I don't
remember exactly the reason for this (maybe we couldn't find a
Recognized dc thermostat that opened), but the design was OK'ed by our
NRTL engineer.
Regards,
Don Gies, N.C.E
Senior Product Compliance Engineer
Lucent Technologies
Holmdel, NJ 07733 USA
From: Gregory H. McClure [mailto:gmccl...@lexmark.com]
Sent: Thursday, October 05, 2006 12:25 PM
To: EMC-PSTC@listserv.ieee.org
Subject: shorting the mains prohibited - Help
Gentlemen,
I need your collective memory.
I have an engineer that wishes to design a protection mechanism to apply
a short circuit across the mains in order to open a protection device
upstream to stop an over-heating fault. The protection device would be
in the product, we are not talking about depending on the protection in
the service panel. I will not let them go there.
I remember somewhere in the past that one of the standards, or perhaps a
country deviation, specifically forbid shorting the mains as a means of
protection but I cannot find it. I think it is from the era when we were
using IEC 380 or 435 and UL 478 but I am not sure.
Can someone out there point me to the standard and clause? or perhaps
the deviation or an OSM decision?
I am looking for all of the arguments against this practice I can pull
together because I do not feel it is sound. It is one thing to crowbar
the output of a power supply to protect an expensive logic board from a
power supply over-voltage failure. It is quite another to short the
mains input.
Many thanks,
Gregory H. McClure
Lexmark Product Safety
859 232 3240 office
859 232 6882 fax
Confidentiality Notice:
This e-mail message, including any attachment, is for the sole use of
the intended recipient(s) and may contain confidential information. Any
unauthorized review, use, disclosure or distribution is strictly
prohibited. If you are not the intended recipient, please contact the
sender, by e-mail, and destroy all copies of the original message.
-
This message is from the IEEE Product Safety Engineering Society
emc-pstc discussion list. Website: http://www.ieee-pses.org/
To post a message to the list, send your e-mail to emc-p...@ieee.org
Instructions: http://listserv.ieee.org/request/user-guide.html
List rules: http://www.ieee-pses.org/listrules.html
For help, send mail to the list administrators:
Scott Douglas emcp...@ptcnh.net
Mike Cantwell mcantw...@ieee.org
For policy questions, send mail to:
Jim Bacher: j.bac...@ieee.org
David Heald: emc-p...@daveheald.com
All emc-pstc postings are archived and searchable on the web at:
http://www.ieeecommunities.org/emc-pstc
-
This message is from the IEEE Product Safety Engineering Society
emc-pstc discussion list. Website: http://www.ieee-pses.org/
To post a message to the list, send your e-mail to emc-p...@ieee.org
Instructions: http://listserv.ieee.org/request/user-guide.html
List rules: http://www.ieee-pses.org/listrules.html
For help, send mail to the list administrators:
Scott Douglas emcp...@ptcnh.net
Mike Cantwell mcantw...@ieee.org
For policy questions, send mail to:
Jim Bacher: j.bac...@ieee.org
David Heald: emc-p...@daveheald.com
All emc-pstc postings are archived and searchable on the web at:
http://www.ieeecommunities.org/emc-pstc
-
This message is from the IEEE Product Safety Engineering Society
emc-pstc discussion list. Website: http://www.ieee-pses.org/
To post a message to the list, send your e-mail to emc-p...@ieee.org
Instructions: http://listserv.ieee.org/request/user-guide.html
List rules: http://www.ieee-pses.org/listrules.html
For help, send mail to the list administrators:
Scott Douglas emcp...@ptcnh.net
Mike Cantwell mcantw...@ieee.org
For policy questions, send mail to:
Jim Bacher: j.bac...@ieee.org
David Heald: emc-p...@daveheald.com
All emc-pstc postings are archived and searchable on the web at:
http://www.ieeecommunities.org/emc-pstc
-
This message is from the IEEE Product Safety Engineering Society
emc-pstc discussion list. Website: http://www.ieee-pses.org/
To post a message to the list, send your e-mail to emc-p...@ieee.org
Instructions: http://listserv.ieee.org/request/user-guide.html
List rules: http://www.ieee-pses.org/listrules.html
For help, send mail to the list administrators:
Scott Douglas emcp...@ptcnh.net
Mike Cantwell mcantw...@ieee.org
For policy questions, send mail to:
Jim Bacher: j.bac...@ieee.org
David Heald: emc-p...@daveheald.com
All emc-pstc postings are archived and searchable on the web at:
http://www.ieeecommunities.org/emc-pstc
______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
For more information please visit http://www.messagelabs.com/email
______________________________________________________________________
