No. You aren't applying the rule correctly. As I stated earlier:
log a*b = log a + log b
log b^n = n log b
Combining, it is clear that
log (a*b^n) = log a + n log b.
--
From: umbdenst...@sensormatic.com
To: emc-p...@majordomo.ieee.org, dmck...@corp.auspex.com
Subject: duty cycle
Hi Peter:
Any limitations/requirements for amount of light emitted from professional
photography flashes? Any UL, IEC or European standards which specify
limitations?
I know how many you like being photographed - but imagine what harm one of
these flashes can cause to your
Going back to fundamentals --
Given a = duty cycle = average power
and define ^2 = squared
Then P[ave] = a P[ref]
P = V^2/R
V[ave]^2/R = aV[ref]^2/R, the Rs cancel leaving
V[ave]^2 = aV[ref]^2
10 log(V[ave]^2) = 10 log (aV[ref]^2), which is equivalent to
20 log (V[ave]) = 20 log
More to the proof discussion launched by the duty cycle question,
given
dB = 10 log (P1/P2)
Let a be the duty cycle ratio, with 0a1, so that P1 = aP2.
Then dB = 10 log (aP2/P2) = 10 log (a). Eq.
(1)
If 10 log (P1/P2) = 10 log (V1^2/V2^2) = 10 log (V1/V2)^2 = 20 log
(V1/V2),
If there aren't standards there probably should be. I remember seeing a
NOVA episode in which Dr. Harold Edgerton, inventor of the strobe,
demonstrated a strobe similar to that used during WWII to photograph German
positions from the air at night. He fired the strobe at a newspaper 3 feet
away
Neither endorsing or rejecting these breakers I just happen to be
doing a little research of my own and have a spec sheet open in front of me
on these things.
Square D has a Multi-9 series of breakers that shows an operating
temperature of -30 to -70 C. and tropical treatment 2
For the latest developments on CENELEC (EN) standards you can go directly to
their website search and just type in the standard number in the Standard
reference field (http://www.cenelec.org/BASIS/celis/free/project/SF).
Nick Momcilovic
Product Safety Coordinator
QTI
N64W23110 Main Street
Folks,
It was pointed out that my quote from SEMI S2-0200e is incorrect. I would
like to restate my question to include the correction. I apologize for any
inconvenience my error has caused. My corrected question is as follows.
.
Can anyone cite a reference document /
Kristiaan
In my experience when CBs operate above or close to 40degC, they will
potentially operate below the rating trip point, leading to spurious
trips. Especially on start up with in rush current. A CB manufacturer should be
able to provide you with the devices performance curves,
fault
In typical testing of DC units,
the two inputs are floating
when doing for example: current checks
and hipot to chassis ground.
Yet, in a CO, the return lead is grounded,
so you have a test lab condition ( return floating )
and a real condition, return tied to CO earth ground
in service.
The
Hi Paul,
Sound pressure level (SPL) is normally given for sustained or peak levels for
different environments. The dB(A) unit for SPL is relative to the threshold
of hearing. The A in the dB(A) indicates the measurement is taken with an
A-weighted filter which shapes the frequency response in a
Dear All,
Any limitations/requirements for amount of light emitted from professional
photography flashes? Any UL, IEC or European standards which specify
limitations?
I know how many you like being photographed - but imagine what harm one of
these flashes can cause to your eyes!
This e-mail
Your eqn (2) is in error. This is how it works.
10 log (aV2^2/V2^2) = 10 log (a) + 10 log (V2/V2)^2 = 10 log (a) + 20 log
(V2/V2) = 10 log (a)
--
From: umbdenst...@sensormatic.com
To: emc-p...@majordomo.ieee.org
Subject: RE: Is This Right?
Date: Fri, Oct 19, 2001, 8:37 AM
More to
You are missing the fact you have your brackets wrong in:
dB = 10 log (aV2^2/V2^2) = 10 log (aV2/V2)^2 = 20 log (a) ? Eq. (2)
should be
dB = 10 log (a (V2^2/V2^2)) = 10 log a ((V2/V2)^2) = 10 log (a)Eq.
(2)
-Original Message-
From: umbdenst...@sensormatic.com
I heard that the IEC has issued the new 60601-1-2 EMC standard for medical
equipment on the 30th of September.
Does anyone know when the EN will follow and when its DOW will be?
Thanks,
Bob Heller
3M Product Safety, 76-1-01
St. Paul, MN 55107-1208
Tel: 651- 778-6336
Fax: 651-778-6252
Hello group,
Circuit breakers and residual current operated circuitbreakers for house-hold
applications are typically cetified at 40 degree Celcius.
If these types are built into other products, they do not comply with their
temperature rating as specified in the safety certificate.
Does
Folks,
Can anyone cite a reference document / standard that determines if there is
a minimum dBA sound level variation above an expected ambient environment
that is suitable for a pulsing alarm.
In my review , I have found that SEMI S2-0200E Environmental, Health, and
Safety Guideline
for
More to the proof discussion launched by the duty cycle question, given
dB = 10 log (P1/P2)
Let a be the duty cycle ratio, with 0a1, so that P1 = aP2.
Then dB = 10 log (aP2/P2) = 10 log (a). Eq.
(1)
If 10 log (P1/P2) = 10 log (V1^2/V2^2) = 10
Hi Guys,
I've been in a lot of trouble this week and had a lot of questions.
But, my way of thinking is...if you're not in a little trouble, you're
not in the game.
Anyway...we want to purchase fiber optic switches for use with our OTDR
(Optical Time Domain Reflectometer) modules. The switches
Mark,
If you think your product is safe, you must be able to prove it. For
starters, I suggest you read UL60950. Somewhere in the Appendix, it allows
one side of the input supply to telecommunication equipment intended for
central office applications to be earthed. However, special markings andf
Mark.
As described, the situation to me sounds no worse than any other earthed
connection. The only hazard would seem to be as a return for hazardous
voltages - exactly the same situation as the sheet metal enclosure that
surrounds it. In my experience sometimes the approver's representative
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