Thanks for the clarification. I agree they should not be used as switches for
switching the full load on and off. This will wear them out in short order and
then they will not work as breakers anymore. Using them to switch off power
under no/low load conditions is not a problem. For instance, I have my DC/DC
bypassing my main contactor, but in series with my breaker. I almost always
want the DC/DC to be on, but if I do want to turn it off while working on the
truck I can just switch off the breaker. Under these conditions I am only
switching off a couple hundred milliamps.
They can be used as safety devices to switch off full load under fault
conditions. That is their pupose.
Now the poor 15 amp AC breaker that I often trip when pushing my charger too
hard is probably getting due for replacement. I can't begin to tell you how
many times I have tripped it :-)
damon> Date: Wed, 19 Mar 2008 10:30:47 -0600> From: [EMAIL PROTECTED]> To:
[email protected]> Subject: Re: [ElectricMotorcycles] eBay:
Airpax 150 Amp 80 Volt DC Circuit Breaker (old discussion revived)> > Breakers
are not switches in the true sense of the word especially> where DC and high
currents are used, if they were then they would be> sold as a Switch-breaker.
Can you use it as a switch? Sure. Will it> hold up being used as a switch maybe
not! Don't take my word for it,> check with the manufacturer. Engineers will
specify a DC rated switch> and a separate DC rated breaker (or fuse) for each
power circuit. The> electric vehicle kits that are being sold today have a DC
interrupter> of some type to positively disconnect the power from the
controller in> the case of emergency. If you use a breaker as a switch in place
of> this device you risk in an emergency flipping the breaker and having> the
connection stay stuck closed. Beware. Remember the guy who> strapped a Rocket
booster to his Chevy Impala not realizing there was> no "OFF" button to a
rocket booster, once started it runs until the> fuel runs out (myth or real
Darwin award winner - posthumous)... if> the controller faults do you want to
have the bike run until the> battery charge runs out?> > DC unlike AC causes
difficulties in disconnecting from the power. If> you were to put yourself
across 115V AC it is not too difficult to> break the connection, the fact of DC
being steady voltage (no swing> from 115V positive to 0 to 115V negative)
breaking away is difficult> if not impossible (someone may have to physically
bump you out of the> circuit), the same with switches and breakers. Just look
at DC rated> switches, the DC rating is much less than the AC rating because
of> this issue.> > I have used a very large breaker (250 A DC) as a switch with
a very> large fuse in 72V battery based systems and had no issues YET. Peace.>
Jeff> On Wed, Mar 19, 2008 at 9:20 AM, damon henry <[EMAIL PROTECTED]> wrote:>
>> >> > Your understanding and mine or the same. Perhaps Jeff Blamey was
thinking> > of AC versus DC ratings. I have one of these circuit breakers in my
truck> > and expect it to be able to break full pack current at full voltage
(80> > volts of BB600 Nicads). Of course, I also have a fuse and a main
contactor> > which should be up to the task as well and retained my clutch for
a physical> > disconnect.> >> > damon> >> >> >
________________________________> > Date: Tue, 18 Mar 2008 23:58:32 -0600> >
From: [EMAIL PROTECTED]> > To: [email protected]> > Subject: Re:
[ElectricMotorcycles] eBay: Airpax 150 Amp 80 Volt DC Circuit> > Breaker (old
discussion revived)> >> >> >> > I noticed these are still up. I also reviewed
some of this discussion, to> > try and understand the potential safety issue of
using a circuit breaker.> >> > Jeff Blamey:> >> > Don't mistake a DC breaker
for a DC disconnect. A DC disconnect has a> > positive break capability up to
the rated capacity.> >> > What's the use of a breaker if it doesn't have a
positive break capability?> > Isn't that it's purpose to begin with?> >> > Jeff
Blamey:> >> > A dc disconnect is a positive shut-off with contacts meant to
make/break> > large current, a breaker could become stuck (or unreliable as a
shut-off)> > and with the current these batteries hold, watch out!> >> > Isn't
that the reason for an arc interrupt current (AIC) rating? I checked> > the
original breaker this discussion was about, ebay item: 290058376726, and> >
it's rated at 10,000. Does this mean it can break 10,000 amps, or am I> >
missing something?> >> > Regards,> > Andrew> >> >> > On Sat, Mar 24, 2007 at
6:42 PM, Mike <[EMAIL PROTECTED]> wrote:> >> > I was poking around eBay,
waiting for the spray paint to dry on some> > ebike parts, and found this:
Airpax 150 Amp 80 Volt DC Circuit> > Breaker with a buy it now for $5. Item
number: 290058376726> >> > # DC Circuit Breaker> > # Maximum Voltage 80 Volts
DC> > # Rated Amperage 150 Amps> > # Trip Amps 180> > # Delay 52> > # Auxiliary
Switch N.O/N.C. 10 Amp 250 Volt AC> > # Panel Mount> > # Approximate Dimensions
1-1/2" Wide x 2-1/2" Long x 3-14" High> > # New Surplus> >> > Dunno if anyone
is interested or not but I thought I'd run it up the flag> > pole.> >> > --> >>
> The Electric Motorcycle Portal> > http://www.electricmotorcycles.net/> >> >
Electric Motorcycle Listserv> > http://www.electricmotorcycles.net/listserv> >>
>> >> > ________________________________> > Climb to the top of the charts!
Play the word scramble challenge with star> > power. Play now!>
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