Ralph, et al,
So I won't take the time to fully defend the requirements but will
point out that it is difficult to get good data on VF in humans. The data is
reported in IEC 60479 series 'Effects of current on human beings...'. In
spite of these difficulties, the result is inferred from a number of animal
experiments as well as reviewing accident data etc; and the results are
astoundingly good in the overall sense. There are complexities in application
of the data which cannot be totally discussed in the short context we have
here. Nor will we deal with the ramifications of the application of the data
in any specific instance.
The American system focuses on keeping folks from getting hung-up on
equipment under normal and fault conditions. The Euro system focuses more on
not killing folks - in spite of the discussion here. I would never
characterize them as 'same level of protection' except in the most general
sense.
Having worked with this collection of medical Dr researchers and
engineers for more than 25 years I have the greatest respect for them and their
work.
:>) br, Pete
Peter E Perkins, PE
Principal Product Safety & Regulatory Affairs Consultant
PO Box 23427
Tigard, ORe 97281-3427
503/452-1201
IEEE Life Fellow
[email protected]
-----Original Message-----
From: Ralph McDiarmid [mailto:[email protected]]
Sent: Wednesday, January 31, 2018 10:03 AM
To: [email protected]
Subject: Re: [PSES] GFCI vs GFPE discussion
“current limit of 30mA protects 95 % of the population”
They didn’t want to try for 100% ? I'm no expert and I don't know if we
have one on this forum for this complex topic, but ask how can one limit be 5X
the other and still afford the same level of protection? Perhaps not intended
to, as in shock versus electrocution protection.
Is 6mA enough for strong muscle reaction or a startle reaction sufficient to
cause someone to loose balance for instance?
Still, some protection better than none at all.
Ralph McDiarmid
Product Compliance Specialist
Solar Business
Schneider Electric
From: Pete Perkins [mailto:[email protected]]
Sent: Tuesday, January 30, 2018 10:06 PM
To: [email protected]
Subject: Re: [PSES] GFCI vs GFPE discussion
Brian, et al
Low current protection devices are intended to protect people.
The long term letgo-immobilization current of 5mA covers the
full population and opens any circuit which exceeds this level (ok, the UL
limit for GFCIs is 4mA to 6 mA), But you get the idea.
The long term Ventricular Fibrillation current limit of 30mA
protects 95 % of the population on the face of the earth. The Euro systems use
of RCDs require this protection in many installations (but I’m not familiar
with the installation code details).
Here in the US we are developing protection devices that will
work at 15 mA and 25 mA. These are intended for use with charging electric
vehicles. The 15 mA device will be used in residential installations and the
25 mA device will be used in commercial installations (haven’t followed the
code development but believe that this is how it is going).
All of these devices have been designed for sinusoidal AC
systems and they all have false tripping issues when used with equipment with
line switching. SMPS and VSD units are a problem today in that they trip a
small number of protection devices; their use is spreading into many more types
of products. From my perspective the units each have a statistical range of
protection or operation and they seem to overlap a small percentage of the
time; this gives rise to ‘nuisance tripping’ (meaning undiagnosed tripping).
This is an issue both in North America (GFCI & AFCI country) as well as the
EuroZone (RCD devices).
I worked with a student project last year which published a
paper for the 2017 IEEE PSES ISPCE Symposium; Yuen et al, ‘Why do GFCIs keep
tripping’. This paper show that some GFCIs can be tricked into operating when
they shouldn’t.
The non-sinusoidal nature of the earth/ground current as well as
the CM/DM signals have not been fully understood nor taken care of in a
harmonized way between the protection device and the load.
Lot’s of opportunity here for investigation and recommendation
of mitigation techniques.
:>) br, Pete
Peter E Perkins, PE
Principal Product Safety & Regulatory Affairs Consultant PO Box 23427 Tigard,
ORe 97281-3427
503/452-1201
IEEE Life Fellow
mailto:[email protected]
From: Kunde, Brian [mailto:[email protected]]
Sent: Tuesday, January 30, 2018 2:04 PM
To: mailto:[email protected]
Subject: [PSES] GFCI vs GFPE
I’ve recently come to understand that the 30mA Ground-Fault protectors, often
built into a circuit breaker, is intended to protect the Protective Earth
(Safety Ground) circuit in the case of a short circuit (opening the circuit
before the safety ground could be damaged. It this correct?
Here is my question. I’m evaluating a cut-off saw (5hp) which uses water to
keep the blade and material cool. The manufacturer uses a 3-phase
supplementary circuit breaker which includes the 30mA GFPE option. This is a
very expensive part. When I asked them why they use the GFPE part, they
couldn’t give me a good answer.
Would such a part be required on a 3-phase motor driven cutoff saw in either
North America or Europe? What standard would dictate this?
If the only purpose of a GFPE is to protect the Ground Circuit, on products
that can handle shorts without damaging the ground circuit, would a GFPE still
be necessary?
Where are GFPE typically used? What industry?
Please educate me. This is a new one on me.
Thanks,
Brian
From: Doug Nix [mailto:[email protected]]
Sent: Friday, January 26, 2018 2:48 PM
To: mailto:[email protected]
Subject: [PSES] JOB POSTING - ONTARIO, CANADA
PLEASE CONTACT TED TYCZKA DIRECTLY
A very notable, “high-profile” client who is seeking a Safety & Services
Sales/Business Development Professional - to join their Machine Services
Division - the focus of the role is to spearhead/lead the sale of Engineering
Services related to “functional safety.”
The company sells safety training (workshops), machine assessment/audits,
engineering design per CSA and/or TUV Safety requirements (“Regulatory
Compliance”). The company also sells Remediation and Repair Services (of
industrial machines) together with Service Contracts ... to customers in the
aerospace, automotive, forestry, food & beverage, as well as, the packaging
sectors.
The Safety & Services/Business Development Professional can work from a home
office - anywhere in Ontario. A Bachelor of Science in Mechanical or Electrical
Engineering, together with the sale of Machine Safeguard devices and the
application of these, would be desired ... together, with some exposure to
Industrial Automation and perhaps Robotics. The key is to have some knowledge
of safety components, safety scanners, switches, controllers, etc. as well as
machine building experience.
The employer (a very reputable, Global entity/brand) ... who provide a very
competitive base salary, lucrative annual bonus/incentive program vs. results,
plus monthly car allowance, Benefits, Matching RRSP + (Training, Career
Opportunities and upward mobility).
They are good people, seek an ambitious self-starter who can cover sales from
the “shop floor” level to the “C Suite” (Boardroom). The company have
established Sales Reps across Canada ... who can work with the Safety &
Services Sales Specialist ... this role requires “consultative and solutions
oriented selling ability.
I will ensure absolute confidentiality. Nice opportunity with a great
organization and strong, capable leadership. Thanks.
Kind professional regards,
Ted Tyczka
President
Golden Mile Management – Consulting Services
2630 Eglinton Avenue East, Toronto, Ontario M1K 2S3
Tel: (416) 266 - 4434
Email: mailto:[email protected]
Website: http://www.gmmcs.com/
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