I believe the zap-stop is to remove spikes on the excitation input to
the alternator by shunting them to ground. The fuse is there in case
the diode shorts in which case you would otherwise have +12 connected
to ground..

On Thu, 10 Jul 2003 10:32:15 -0700, "Steve" wrote:

Several of you have suggested the Zap-Stop to shunt the alternator output
to ground, if the battery is disconnected or the inline fuse were to blow..

Sounded like a workable solution until I read the discription in their ad.
"ZAP-STOP, along with the integral 20 amp slow-blow fuse,...." .

My alternator is capable of 100 amp and the AUTOMAC II is going to be
regulating the output up to that rating. If I have a 100 amp fuse in the
line between the alternator output terminal and the battery disconnect
switch and that fuse blows, then the 20 amp fuse in the Zap-Stop is also
going to blow. This would then render the Zap-Stop useless.

What am I missing here??

Steve
s/v Good Intentions


Bill in Seattle

wrote in message
news
I believe the zap-stop is to remove spikes on the excitation input to
the alternator by shunting them to ground. The fuse is there in case
the diode shorts in which case you would otherwise have +12 connected
to ground..

See, that's the problem with this Zap-stop. A lot of people saying what they
believe it will do for them. Technical data at the Xantrex site is darn
slim, so wishful speculation abounds.

Extraordinary claims demand extraordinary proof. I wanna see a schematic, I
wanna see suppressed transient waveforms, show me why Zap-stop is better
than a zener or MOV or SiC or Transorb or a gas tube!


Ed

"Ed Price" wrote in message news:DPtQa.417$ Extraordinary claims demand extraordinary proof. I wanna see a schematic, I
wanna see suppressed transient waveforms, show me why Zap-stop is better
than a zener or MOV or SiC or Transorb or a gas tube!


Ed

I believe the zap stop is just a zener in series with a slow blow
fuse. You could make one for a lot less than they charge

On 24 Jul 2003 15:35:55 -0700, (Jim Balsley)
wrote:

"Ed Price" wrote in message news:DPtQa.417$ Extraordinary claims demand extraordinary proof. I wanna see a schematic, I
wanna see suppressed transient waveforms, show me why Zap-stop is better
than a zener or MOV or SiC or Transorb or a gas tube!


Ed

I believe the zap stop is just a zener in series with a slow blow
fuse. You could make one for a lot less than they charge

There are several ways to approach this, depending on the alternator.
I don't like integrated regulators because they are hard to safely
control. Particularly those that supply their own field current when
they are running (get starting current through the charge lamp) and
ground the field internally through the regulator. By disconnecting
the trio diodes internally from the regulator, you can convert many of
these alternators to ecternally excited units -supply field current
through the "L" terminal.

External regulator units are obviously simpler.

Now you just need a "crowbar" circuit (like the zap-stopper) on the
regulator feed, with a fuse between the crowbat and the battery/ign
switch. If the voltage excedes 15 volts (or whatever voltage you
design for) the circuit clamps the field and blows the field supply
fuse - guaranteeing you will NOT get overvoltages. Now, if you want to
fuse the output, you need to have an NC relay in the field circuit
controlled by the output of the alternator, and you need to charge the
battery though a diode so when the fuse blows there is no voltage to
the relay coil, and the field drops. Final piece of the puzzle is to
provide startup current to the field, so the alternator can produce
power to close the relay to energize the field. This can be done by
providing power directly to the field(alternator side of field relay)
or to the coil of the relay during cranking.

On Sat, 19 Mar 2005 00:31:02 -0500,
wrote:

On 24 Jul 2003 15:35:55 -0700, (Jim Balsley)
wrote:

"Ed Price" wrote in message news:DPtQa.417$ Extraordinary claims demand extraordinary proof. I wanna see a schematic, I
wanna see suppressed transient waveforms, show me why Zap-stop is better
than a zener or MOV or SiC or Transorb or a gas tube!


Ed

I believe the zap stop is just a zener in series with a slow blow
fuse. You could make one for a lot less than they charge

There are several ways to approach this, depending on the alternator.
I don't like integrated regulators because they are hard to safely
control. Particularly those that supply their own field current when
they are running (get starting current through the charge lamp) and
ground the field internally through the regulator. By disconnecting
the trio diodes internally from the regulator, you can convert many of
these alternators to ecternally excited units -supply field current
through the "L" terminal.

External regulator units are obviously simpler.

Now you just need a "crowbar" circuit (like the zap-stopper) on the
regulator feed, with a fuse between the crowbat and the battery/ign
switch. If the voltage excedes 15 volts (or whatever voltage you
design for) the circuit clamps the field and blows the field supply
fuse - guaranteeing you will NOT get overvoltages. Now, if you want to
fuse the output, you need to have an NC relay in the field circuit
controlled by the output of the alternator, and you need to charge the
battery though a diode so when the fuse blows there is no voltage to
the relay coil, and the field drops. Final piece of the puzzle is to
provide startup current to the field, so the alternator can produce
power to close the relay to energize the field. This can be done by
providing power directly to the field(alternator side of field relay)
or to the coil of the relay during cranking.

And what do you do about the already charged field in the alternator
when the battery gets disconnected? It is already too late.
That's why the zap stop goes across the output of the alternator.

Regards
Gary

The inside of the ZapStop is an MR2535L avalance diode. Cost about $1.40 in
quantity 10 at Digikey. It will take a 600 amp hit. Wired backwards across
the alternator output it will break down under the high voltage as the field
collapses and short it more or less harmlessly.

--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
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