Back to Brian's mail about the basis for the 1500A interrupt rating, my
assumption has been that it stems from some other common requirement or
application that made this the next step up. Presumably it isn't economical to
have a bunch of different common interrupt ratings.
Cheers,
Gary
My assumption as well
Perhaps, but keep in mind that the impedance specified by 60725 is a maximum
value that 90% of household service would not exceed. It might be 1/2 that
value on average.
Ralph McDiarmid
Product Compliance
Engineering
Solar Business
Schneider Electric
In UK, because of the ring-main wiring, the effective conductors to a
wall-socket are 5 mm^2.
John Woodgate OOO-Own Opinions Only
J M Woodgate and Associates www.woodjohn.uk
Rayleigh, Essex UK
On 2017-11-20 20:21, Richard Nute wrote:
In the USA, at the load end of a 2-meter #18 power cord,
I suspect the IEC 60725 impedance is at the service entrance, not through the
breaker box, building wiring, connectors, and power cord. By the time all
these resistances are taken into account, I suspect that the total resistance
is at least twice that specified in IEC 60725.
Rich
In the USA, at the load end of a 2-meter #18 power cord, you can expect 100-200
amps short-circuit current, but not more, due to the resistance of the power
cord, the connectors, and the wiring to the breaker box.
If you assume that the source resistance is almost 1 ohm, the short-circuit
Ralph, et al,
My long term understanding is that the fault current is a curve. High
values initially draining to lower values as the stored charge in the adjacent
wiring is pulled thru the short circuit and maintained by the supply impedance
at the longer term value.
'Reference value' 0.4 + j0.25 ohms in IEC TR 60725 for household-type
single phase connections, leading to a fault current of 488 A at 230 V.
But impedances lower than the reference value occur quite widely in some
countries. I measure about 80% of the reference value at a wall socket,
not
According to IEC/TR 60725, 90% of customers in the UK and in Australia, will
have electricity supply impedance less than or equal to 0.25 + j0.23 ohms.
That according to a survey or residential service for 230V/50Hz
That tells me that short circuit current would be at least 680A, but could be
Mr. Woodgate,
Is there a recently published spec for a 'typical' 230V mains impedance for the
EU? Have also noted that the source Zs in 61000-4-5 for the instrument seem
rather high. So what is the basis for 1500A interrupt rating?
For U.S., even for an artificially low-Z electronic AC source,
9 matches
Mail list logo
