Has anyone got a circuit to make up one of these for Steel canal boat
please. I have been recommended to go for about 70 amps.

mack wrote:
Has anyone got a circuit to make up one of these for Steel canal boat
please. I have been recommended to go for about 70 amps.





This should get you started. Unless you really know what you
are doing, you would be wise to obtain some assistance
before building or installing an isolator.

Good Luck!

Chuck

http://www.yandina.com/galvanicIsolator.htm
Galvanic Isolator Explained

On Thu, 10 Feb 2005 15:01:42 -0000, "mack"
wrote:

Has anyone got a circuit to make up one of these for Steel canal boat
please. I have been recommended to go for about 70 amps.


You need four silicon rectifier diodes rated at 70 amps or more (low
voltage rating is OK). Connect them in two series pairs (anode of one
to cathode of the other), then connect the two series pairs in
parallel, but in opposite polarity, between the shore power green wire
and boat ground (battery negative/engine block/etc.).




--
Peter Bennett, VE7CEI
peterbb4 (at) interchange.ubc.ca
new newsgroup users info : http://vancouver-webpages.com/nnq
GPS and NMEA info: http://vancouver-webpages.com/peter
Vancouver Power Squadron: http://vancouver.powersquadron.ca

On 2005-02-26 12:38:34 +1100, Sir Spamalot said:

On Fri, 25 Feb 2005 22:27:31 GMT, John Proctor
wrote:

On 2005-02-25 12:44:20 +1100, chuck said:

Hello Eric,

Thanks for clarifying.

I believe you are correct. You are talking about high-resistance
onboard leakages that generate currents too small to be detected by the
GFI circuit or the breakers. The isolator diodes would probably not
conduct under those circumstances and a capacitor would help.

UL requires the GFI to trip at a 5 ma unbalance, so 24,000 ohms of
leakage would trip it. Actually, the isolator diodes would probably
pass 5 ma in that circuit without a capacitor. The capacitor would be
necessary when the leakage resistance was in the megohms and the
currents in the microamps.

Would rather not have that stuff flowing through my ground connections
through the water to adjacent boats, even at those low current levels.
This underscores the importance of making sure you don't have dangerous
leakages onboard in the first place. Easy enough to check, but how many
regularly test their GFIs?

We sure agree on the isolation transformer, too.

Thanks again, Eric.

Chuck

Chuck,

I am puzzled by your UL 5 ma rating.

Here in Australia we have basically two ratings. The first is for most
domestic installations an is 30 ma. The second is for hazerdous
locations including hospitals where the rating is 10 ma. There are
other higher rating RCD (Residual Current Devices) which are used in
industrial contexts (eg 60 ma) but the majority of installations are
either 30 ma. or 10 ma.

BTW I am an EE as well as a licensed Electrical Contractor.


Chuck,

Now **I** am puzzled by the Australian ratings, especially since my
sister lives "across the pond" in NZ. 30ma has been known to kill,
hence I question the 30ma "domestic installation" rating. And you
guys are on 240V, correct?

Are we discussing semantics here? In the US, a GFI (120V) is supposed
to protect the unknowing public from faults that could channel more
than 5ma through the body. UL/CSA/others test to that 5ma
specification.

SS


PS: Me too on the EE business.

Curiouser and curiouser...

In Australia we have generally what is called a multiply earthed
neutral system (MEN). There are other types of distributution systems
used in remote areas but MEN system is found in all urban areas. In
this system n+1 service conductors (where n = number of phases) are
brought into the consumer's premises although if available on the
distributiuon system 3 phase power is much easier to obtain here than
in NA (I originally came from Canada). This phase active and netral in
a single phase supply is the normal residential. The neutral is boded
to earth at each consumer switchboard and the earth is bonded to a
ground system which is normally a grounding rod of reasonable size.
Some allowances are made for installations where a ground rod is not
practical or where it cannot be of sufficient size. It has not been
acceptable to ground to utility services (gas or water) for some number
of years due to lack of guaranteed continuity (gas reticulation is via
plastic pipes and water meters har generally non metalic internally).

I have generally seen in the literature that 60 ma is generally
considered the level at which statistically fibrillation is almost
guaranteed when the current passes through the chest cavity. Some of
the references given seem to indicate much lower levels. However when
standards are set they must take into account the statistical nature of
some of the effects they are trying to deal with. Hence I think the 30
ma residential rating here in Australia. The AS/NZS 3000:2000 Wiring
Rules specifies an maximum RCD rating of 30 ma for residential circuits
and I don't believe there are any addendums which mandate a lower
maximum. As I indicated in my previous post the 10 ma level is required
in hospitals or other high risk application areas. However you need to
balance emi filtering requirements with leakage levels so that you
don't get nuisance tripping.

I don't know about New Zealand but given the nature of trans-Tasman
standards activities I would be surprised if their wiring rules were
significantly different from ours. After all we use the same wiring
rules!

In residential installations an RCD (residual current device) is
required on general purpose outlets and lighting circuits but does not
need to be applied to direct connection appliances like cooktops or
stoves. However practice has evolved so that 'safety switches' (RCDs)
are placed on the whole installation (for older installations) as these
are easier to wire into old and cramped switchboards. New installations
segregate the power, lighting and direct connected appliances and have
an RCD on the appropriate circuits. Some contractors also will provide
unprotected circuits for essential circuits (refrigerators, freezers
etc.) to prevent food spoilage from nuisance tripping where the outlet
is set up for fixed use.

In the case of marinas there is usually a 16A branch circuit protected
by a 30 ma RCD supplying shore power to the vessel. Unfortuanately, I
don't have any experience with larger vessels where 3 phase power from
shore is delivered but I would expect the situaltion to be similar with
n+1+1 conductors being delivered to the boat (where n = number of
phases and the extra +1 is the earth). It is mandatory that earth and
neutral be kept separate on the vessel. Installations where there are
changeover facilities to a genset require the earth and neutral to be
bonded only when the genset is the power source.

Sorry about the length but that is generally how things work downunder.

--
Regards,
John Proctor VK3JP, VKV6789
S/V Chagall

Hi: I am a uk manufacturer of galvanic isolators 70 amps rated & supplied with or without status monitor : Our website is www.galvanicisolators.com :may i suggest you look at our helpfiles & I'm sure you will find valuable information within: please note : we construct & test our isolators to a very high standard not easily attained by d.i.y. projectors. heat sinking is vital & quality of components must be a1. isolators are a safety device & must be treated with great respect!I hope the website is of help to you ..Regards ..Vic..If You need further advice please email

vic wilkinson wrote in
:

Hi: I am a uk manufacturer of galvanic isolators 70 amps rated &
supplied with or without status monitor : Our website is
www.galvanicisolators.com :may i suggest you look at our helpfiles &
I'm sure you will find valuable information within: please note : we
construct & test our isolators to a very high standard not easily
attained by d.i.y. projectors. heat sinking is vital & quality of
components must be a1. isolators are a safety device & must be treated
with great respect!I hope the website is of help to you ..Regards
.Vic..If You need further advice please email




Hmm....If we take a Micro Commercial Components MP5005 50A 50V bridge
rectifier ($6.40 in single quantities, under $5 if you buy 100 at a time
from DigiKey) and bolt it to a single hole heatsink ($3 at any electronics
parts house, cheaper if I buy heat sink on the surplus market) we can
create a 1-component galvanic isolator by simply connecting our in/out
green ground wires to the AC posts on the beast and shorting out the + and
- DC posts, effectively putting two 50A diodes in series (1.2V drop) going
each way (4 diodes in the single phase bridge rectifier)......total cost $8
and change plus a little shipping...(c;

Because the heat sink of this bridge is isolated from all the posts, we
could just bolt it to the inside of a metal power panel and use that as a
heat sink, getting our parts count down to ONE and reducing our assembly
time to near zero! All we'll have to do is repackage them in a fancy box
with a boat looking logo. The only time it gets warm is when there's a
short to ground for a few milliseconds before the shore power breaker
trips. This device will stand a 400 amp repetitive surge at 50/60 Hz.

Now if I can get gullible boaters to pay $299 for the "marine" version
painted blue with the anchor or ships wheel logo stuck to the side of it, I
can make a tidy sum of $280-290 per unit for my trouble....minus Waste
Marine's cut if they buy it to resell.

Not bad at all. Just use the same disclaimer this guy uses saying I'm not
responsible for anything that happens to boat or boaters if he uses this
device. Hmm...I got a DigiKey account....(c;

Special discount to rec.boats.electronics posters, of course, $159.95 plus
shipping....(c; Buy direct from the manufacturer, "Marine Protection
Division", AmpZ Electronics...ME!

(c;

If only life were so simple!!!!
to manufacture isolators they must be ce approved & pass many application tests. They must be able to withstand dc currents (not just ac currents) & must have heatsinks capable of withstanding high temperatures for prolonged time (not milliseconds as you state!) Potential installers must be aware that this is a safety device & must be constructed to a high standard. Diy is fine but its a case of buyer beware!....If you are not 100% confident in your ability to construct a safe isolator then buy a commercial one... Our 70 amp isolators retail @£59.99 & our version with remote status monitor @ £79.99.
if you need further info log onto www.galvanicisolators.com.

vic wilkinson wrote in
:

to manufacture isolators they must be ce approved & pass many
application tests. They must be able to withstand dc currents (not just
ac currents) & must have heatsinks capable of withstanding high
temperatures for prolonged time (not milliseconds as you state!)


The European Union's Electromagnetic Compatibility (EMC) Directive
89/336/EEC outlines the requirements for electrical apparatus to control
interference by establishing 'essential requirements' for all electrical
goods.
"The electrical apparatus shall be so constructed that:
a) The electromagnetic disturbance it generates does not exceed a
level allowing radio and telecommunications equipment and other apparatus
to operate as intended.
b) The apparatus has an adequate level of intrinsic immunity to
electromagnetic disturbance enabling the device to operate as intended."

The European Union's harmonized EMC Standards provide guidelines and limits
for testing and include descriptions of test layout and methods, as well as
defined maximum permissible limits of electro-magnetic emission and
immunity levels.

Shouldn't be a problem getting 4 diodes to pass an EMC test that don't
conduct in normal use, eh?

50A not enough DC current? It's a RECTIFIER, after all... There's a 100A
version for a few bucks more. Let's face it, your product is just 4 diodes
on a heatsink. I'd bet my $8 bridge on a heat sink makes the same heat as
your 4 diodes on a heatsink. The bridge is made for 50A continuous DC
current (or 100A if you insist we use the bigger bridge). It will still
cost under $15 with a big heat sink if we leave out the "marine" logo
stickers.

The 50A bridge on our boat has tripped many a breaker using the aluminum
breaker panel as a heat sink with some heat sink compound between them. It
hardly gets warm. I'll send UL a shorted bridge rectifier to see if I can
get it certified for USA.

Where's all this DC current coming from, just for information? God, I
can't imagine what 50A DC to the marina ground can do to your boat if all
this DC current were flowing for more than a few minutes. It'd eat the
prop right off the shaft!

Hello again Larry,

Are you recommending diodes with a 50 V (PIV, I assume) rating?

Chuck

Larry W4CSC wrote:
vic wilkinson wrote in
:


Hi: I am a uk manufacturer of galvanic isolators 70 amps rated &
supplied with or without status monitor : Our website is
www.galvanicisolators.com :may i suggest you look at our helpfiles &
I'm sure you will find valuable information within: please note : we
construct & test our isolators to a very high standard not easily
attained by d.i.y. projectors. heat sinking is vital & quality of
components must be a1. isolators are a safety device & must be treated
with great respect!I hope the website is of help to you ..Regards
.Vic..If You need further advice please email





Hmm....If we take a Micro Commercial Components MP5005 50A 50V bridge
rectifier ($6.40 in single quantities, under $5 if you buy 100 at a time
from DigiKey) and bolt it to a single hole heatsink ($3 at any electronics
parts house, cheaper if I buy heat sink on the surplus market) we can
create a 1-component galvanic isolator by simply connecting our in/out
green ground wires to the AC posts on the beast and shorting out the + and
- DC posts, effectively putting two 50A diodes in series (1.2V drop) going
each way (4 diodes in the single phase bridge rectifier)......total cost $8
and change plus a little shipping...(c;

Because the heat sink of this bridge is isolated from all the posts, we
could just bolt it to the inside of a metal power panel and use that as a
heat sink, getting our parts count down to ONE and reducing our assembly
time to near zero! All we'll have to do is repackage them in a fancy box
with a boat looking logo. The only time it gets warm is when there's a
short to ground for a few milliseconds before the shore power breaker
trips. This device will stand a 400 amp repetitive surge at 50/60 Hz.

Now if I can get gullible boaters to pay $299 for the "marine" version
painted blue with the anchor or ships wheel logo stuck to the side of it, I
can make a tidy sum of $280-290 per unit for my trouble....minus Waste
Marine's cut if they buy it to resell.

Not bad at all. Just use the same disclaimer this guy uses saying I'm not
responsible for anything that happens to boat or boaters if he uses this
device. Hmm...I got a DigiKey account....(c;

Special discount to rec.boats.electronics posters, of course, $159.95 plus
shipping....(c; Buy direct from the manufacturer, "Marine Protection
Division", AmpZ Electronics...ME!

(c;

"Larry W4CSC" wrote in message
...
vic wilkinson wrote in
:

to manufacture isolators they must be ce approved & pass many
application tests. They must be able to withstand dc currents (not just
ac currents) & must have heatsinks capable of withstanding high
temperatures for prolonged time (not milliseconds as you state!)


The European Union's Electromagnetic Compatibility (EMC) Directive
89/336/EEC outlines the requirements for electrical apparatus to control
interference by establishing 'essential requirements' for all electrical
goods.

snip

Shouldn't be a problem getting 4 diodes to pass an EMC test that don't
conduct in normal use, eh?

The EMC part is not the problem, you are allowed to test that yourself, if
you have the equipment. But since this device is part of the mains circuit,
other tests will have to be conducted which you are not allowed to do
yourself, you have to hire a notified body for that. And that costs.

Meindert