generator problem

[Jon]

I'm trying to wire a transfer circuit for a generator.

The generator will be located in the barn. The electrical service is at the
house. Two 120vac wires and a ground go to the barn. There is *one* unused
wire from the house to the barn I can use for a signal circuit.

When the power goes off at the house, I need to disconnect the service to
prevent backfeed and activate for generator power to both the house and the
barn. When the service power goes on I need to disconnect the generator to
avoid damaging it and restore normal service to the house and the barn.

I have,

*one 240vac 60 amp dpdt mercury relay
*two 120vac 60 amp 3pdt relays.

Any ideas?

Jon Giffen

 

[Charlie E.]

On Wed, 24 Feb 2010 12:34:25 -0500, "Jon" <jon8338@peoplepc.com>
wrote:

I'm trying to wire a transfer circuit for a generator.

The generator will be located in the barn. The electrical service is at the
house. Two 120vac wires and a ground go to the barn. There is *one* unused
wire from the house to the barn I can use for a signal circuit.

When the power goes off at the house, I need to disconnect the service to
prevent backfeed and activate for generator power to both the house and the
barn. When the service power goes on I need to disconnect the generator to
avoid damaging it and restore normal service to the house and the barn.

I have,

*one 240vac 60 amp dpdt mercury relay
*two 120vac 60 amp 3pdt relays.

Any ideas?

Jon Giffen

First, hire an electrician! There are safety issues involved with
stuff like this that leave you open to liability questions otherwise.

If you insist on doing this yourself, the 240AC relay is used to
isolate from the mains. It should be fail-safe i.e. no power means
that it is connected and the others are not. Your system needs to do
the switching of load to the rest of the circuits.

Charlie

 

[Tim Wescott]

Charlie E. wrote:

On Wed, 24 Feb 2010 12:34:25 -0500, "Jon" <jon8338@peoplepc.com
wrote:

I'm trying to wire a transfer circuit for a generator.

The generator will be located in the barn. The electrical service is at the
house. Two 120vac wires and a ground go to the barn. There is *one* unused
wire from the house to the barn I can use for a signal circuit.

When the power goes off at the house, I need to disconnect the service to
prevent backfeed and activate for generator power to both the house and the
barn. When the service power goes on I need to disconnect the generator to
avoid damaging it and restore normal service to the house and the barn.

I have,

*one 240vac 60 amp dpdt mercury relay
*two 120vac 60 amp 3pdt relays.

Any ideas?

Jon Giffen

First, hire an electrician! There are safety issues involved with
stuff like this that leave you open to liability questions otherwise.

@#$% modern tort laws!

Your personal liability varies by the culture of your state -- the two
examples I know if are Kansas and Oregon. In Oregon, if a neighbor gets
drunk, breaks into your yard, and drowns himself in your kid's wading
pool, then you'll get sued and it might succeed. In Kansas (unless it's
changed since my sister lived there), if a neighbor kid goes swimming in
your backyard pool without permission and drowns himself the jury will
shake their heads and tell the kids parents they should have kept a
closer eye.

<snip>

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com

 

[Tim Wescott]

Jon wrote:

I'm trying to wire a transfer circuit for a generator.

The generator will be located in the barn. The electrical service is at
the house. Two 120vac wires and a ground go to the barn. There is
*one* unused wire from the house to the barn I can use for a signal
circuit.

When the power goes off at the house, I need to disconnect the service
to prevent backfeed and activate for generator power to both the house
and the barn. When the service power goes on I need to disconnect the
generator to avoid damaging it and restore normal service to the house
and the barn.

I have,

*one 240vac 60 amp dpdt mercury relay
*two 120vac 60 amp 3pdt relays.

Any ideas?

Jon Giffen

1: Dig a trench, lay some cable, do it 'right'.

2: Do an enormous science project, and plan on buying more relays.

One way I can think of to do this is to have the generator in the barn
set up to disconnect the _barn_ on power loss, then start itself up.
Power the one wire (against the 120V neutral reference) with what the
generator produces. Then up in the house, use the absence of street
power and the presence of generator power to switch off the street and
onto the generator.

You could complicate this further to automatically switch the generator
off, but you're already looking at a mad scientists dream; were I to do
this (I'd dig the @$%# trench) I'd just plan on _walking_ out to the
barn after the street lights come on and shutting things down manually.

If you're smart you'll check your local codes very carefully before
proceeding -- home generator setups that inadvertently apply power back
to the street can create very hazardous situations for line maintenance
folks, and power companies generally take a dim view of people winging
this sort of design. At the very least you'll need to use some
power-company-approved switchover device that locks out the generator
when you're on street power.

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com

 

[Jim Thompson]

On Wed, 24 Feb 2010 10:31:34 -0800, Tim Wescott <tim@seemywebsite.now>
wrote:

Charlie E. wrote:
On Wed, 24 Feb 2010 12:34:25 -0500, "Jon" <jon8338@peoplepc.com
wrote:

I'm trying to wire a transfer circuit for a generator.

The generator will be located in the barn. The electrical service is at the
house. Two 120vac wires and a ground go to the barn. There is *one* unused
wire from the house to the barn I can use for a signal circuit.

When the power goes off at the house, I need to disconnect the service to
prevent backfeed and activate for generator power to both the house and the
barn. When the service power goes on I need to disconnect the generator to
avoid damaging it and restore normal service to the house and the barn.

I have,

*one 240vac 60 amp dpdt mercury relay
*two 120vac 60 amp 3pdt relays.

Any ideas?

Jon Giffen

First, hire an electrician! There are safety issues involved with
stuff like this that leave you open to liability questions otherwise.

@#$% modern tort laws!

Your personal liability varies by the culture of your state -- the two
examples I know if are Kansas and Oregon. In Oregon, if a neighbor gets
drunk, breaks into your yard, and drowns himself in your kid's wading
pool, then you'll get sued and it might succeed. In Kansas (unless it's
changed since my sister lived there), if a neighbor kid goes swimming in
your backyard pool without permission and drowns himself the jury will
shake their heads and tell the kids parents they should have kept a
closer eye.

snip

In Arizona, self closing/latching gates with releases only on the
inside serve as the tort prevention. If the kid gets inside, he
committed "break-and-enter".

For my own comfort in dealing with eight grandchildren I added double
latches on the house outside doors, requiring at least 5' height and
arm-stretch to match to open them (standing on a stool to reach the
upper puts you out of range to reach the lower at the same time

...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[Jim Thompson]

On Wed, 24 Feb 2010 10:40:02 -0800, Tim Wescott <tim@seemywebsite.now>
wrote:

Jon wrote:
I'm trying to wire a transfer circuit for a generator.

The generator will be located in the barn. The electrical service is at
the house. Two 120vac wires and a ground go to the barn. There is
*one* unused wire from the house to the barn I can use for a signal
circuit.

When the power goes off at the house, I need to disconnect the service
to prevent backfeed and activate for generator power to both the house
and the barn. When the service power goes on I need to disconnect the
generator to avoid damaging it and restore normal service to the house
and the barn.

I have,

*one 240vac 60 amp dpdt mercury relay
*two 120vac 60 amp 3pdt relays.

Any ideas?

Jon Giffen

1: Dig a trench, lay some cable, do it 'right'.

2: Do an enormous science project, and plan on buying more relays.

One way I can think of to do this is to have the generator in the barn
set up to disconnect the _barn_ on power loss, then start itself up.
Power the one wire (against the 120V neutral reference) with what the
generator produces. Then up in the house, use the absence of street
power and the presence of generator power to switch off the street and
onto the generator.

You could complicate this further to automatically switch the generator
off, but you're already looking at a mad scientists dream; were I to do
this (I'd dig the @$%# trench) I'd just plan on _walking_ out to the
barn after the street lights come on and shutting things down manually.

If you're smart you'll check your local codes very carefully before
proceeding -- home generator setups that inadvertently apply power back
to the street can create very hazardous situations for line maintenance
folks, and power companies generally take a dim view of people winging
this sort of design. At the very least you'll need to use some
power-company-approved switchover device that locks out the generator
when you're on street power.

There are MG sets that have automatic switch-over built-in. Back when
I lived in total boonie land I was considering purchasing one. Then
APS upgraded everything.

Now I'm on SRP with relatively modern infrastructure. Only one short
outage in 16 years... a lightning strike on the distribution yard.

...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |

I love to cook with wine. Sometimes I even put it in the food.

 

[Howard Eisenhauer]

1st question- Is the existing wiring out to the barn up to the job?
i.e. how many amps is your genset capable of suplying- 60 amps through
#10 ain't gonna cut it.

2nd- how many amps is your service rated for & how many can the genset
supply? A 60 A feed into a 200A service means you're gonna be
manually flipping brakers off anyhow...

3rd- Is there a seperate main service dissconnect from your breker
panel? If not you'll have to add noe between the meter & panel if you
want the xfer swittch to feed th whole house

4th- how understanding is the carrier for your fire insurance?
Jerry-rigged transfer switches using non-approved parts aside if
there's any problems at all with *any* of your wiring (whether you
were the last one to touch that particular part or not) that causes a
fire you can probably kiss your coverage goodbye

Personally I'd go with a type approved manual transfer switch, with a
seperate feed coming to it from the generator, feeding a "essential
services" sub panel .


Remember- The Life You Save May Be Someone Else's.


H.


On Wed, 24 Feb 2010 12:34:25 -0500, "Jon" <jon8338@peoplepc.com>
wrote:

I'm trying to wire a transfer circuit for a generator.

The generator will be located in the barn. The electrical service is at the
house. Two 120vac wires and a ground go to the barn. There is *one* unused
wire from the house to the barn I can use for a signal circuit.

When the power goes off at the house, I need to disconnect the service to
prevent backfeed and activate for generator power to both the house and the
barn. When the service power goes on I need to disconnect the generator to
avoid damaging it and restore normal service to the house and the barn.

I have,

*one 240vac 60 amp dpdt mercury relay
*two 120vac 60 amp 3pdt relays.

Any ideas?

Jon Giffen

 

[mpm]

On Feb 24, 12:34 pm, "Jon" <jon8...@peoplepc.com> wrote:

I'm trying to wire a transfer circuit for a generator.

The generator will be located in the barn.  The electrical service is at the
house.  Two 120vac wires and a ground go to the barn.  There is *one* unused
wire from the house to the barn I can use for a signal circuit.

When the power goes off at the house, I need to disconnect the service to
prevent backfeed and activate for generator power to both the house and the
barn.  When the service power goes on I need to disconnect the generator to
avoid damaging it and restore normal service to the house and the barn.

I have,

*one 240vac 60 amp dpdt mercury relay
*two 120vac 60 amp 3pdt relays.

Any ideas?

Jon Giffen

Answer: Ask your insurance company if they will buy you a new house
(and barn) if (for any or no reason) the thing catches fire.

You need a listed mechanical switch, not a relay.
You can buy automatic transfer switches, of course - which are a form
of motorized mechanical switches.

As for control wiring to an automatic transfer switch, these are
typically low-voltage, but not always.
Although, most ATS I've seen will sample the utiliity and switch by
themselves, and the control wiring is mostly for cycle-timers and
testing, stuff like that.

If I understand where you're going....
NO. You can not use an extra (unused) wire in the bundle that already
carries the two 120 VAC.
The control wiring is separate. Can't even be in the same conduit.

Of course, check your local codes -- one obvious exception is that the
local Inspector probably has the ability to "approve" anything, but I
wouldn't hold my breath.
Way too much liability.

Go get yourself a real switch, designed for this purpose. Manual or
Automatic.
They cost much less than your house, or yours or someone else's life!

Also, I hope your "extra" wire is not the neutral.
If so, ask yourself what happens if the neutral to your house lifts.
Also, (totally different issue), remember that the Utility and your
generator will not be synchronized.
So, if you attempt an instaneous switchover, at some point, you'll be
high on the AC cycle from the utility, and low on the genertor -- or
vice versa.
This causes maximum current to flow for a split second, and will
probably nuisance-trip the breakers.
You can by phase monitors, but for residential use, a simple time
delay between switch activations should do the trick.
Generator - disconnect (wait) - then switch back to utility.
Easy.

Also, come to think of it, you probably want a safequard to your
generator is not connected until it reaches the proper output and
waveform.


-mpm

 

[Jon]

"Tim Wescott" <tim@seemywebsite.now> wrote in message
news:tYmdnQq2qvI67xjWnZ2dnUVZ_omdnZ2d@web-ster.com...

Jon wrote:
I'm trying to wire a transfer circuit for a generator.

The generator will be located in the barn. The electrical service is at
the house. Two 120vac wires and a ground go to the barn. There is *one*
unused wire from the house to the barn I can use for a signal circuit.

When the power goes off at the house, I need to disconnect the service to
prevent backfeed and activate for generator power to both the house and
the barn. When the service power goes on I need to disconnect the
generator to avoid damaging it and restore normal service to the house
and the barn.

I have,

*one 240vac 60 amp dpdt mercury relay
*two 120vac 60 amp 3pdt relays.

Any ideas?

Jon Giffen

1: Dig a trench, lay some cable, do it 'right'.

2: Do an enormous science project, and plan on buying more relays.

One way I can think of to do this is to have the generator in the barn set
up to disconnect the _barn_ on power loss, then start itself up. Power the
one wire (against the 120V neutral reference) with what the generator
produces. Then up in the house, use the absence of street power and the
presence of generator power to switch off the street and onto the
generator.

You could complicate this further to automatically switch the generator
off, but you're already looking at a mad scientists dream; were I to do
this (I'd dig the @$%# trench) I'd just plan on _walking_ out to the barn
after the street lights come on and shutting things down manually.

If you're smart you'll check your local codes very carefully before
proceeding -- home generator setups that inadvertently apply power back to
the street can create very hazardous situations for line maintenance
folks, and power companies generally take a dim view of people winging
this sort of design. At the very least you'll need to use some
power-company-approved switchover device that locks out the generator when
you're on street power.

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com

Here's what I came up with:

120vac service lines 120vac
| |
| |
| | signal line
*------(coil A)------*--------------*
| | |
| | |
--- --- |
--- --- |
| A | A |
| | |
| | |
o--- house/barn -----o |
| | |
| | |
--- --- |
-/- -/- (coil B)
| B | B |
| | |
| | |
o-----generator------o ---
-
gnd

coil A 240vac contacts 200 amps N.O.
coil B 120vac contacts 100 amps N.C.

I don't need to turn the generator on right away. I just want to take the
guesswork out of turning the main breaker on and off every time the electric
goes out. Then I don't want to have to test if the power goes back on and I
can't tell. With this arrangement I can save trips back and forth to the
house and barn. If this works when the power goes off all we need to do is
go to the barn and fire up the generator.

I guess I could also add a generator kill switch off of coil B.

Let me know what you think.

Where do I find the relays?

 

[Michael A. Terrell]

Jon wrote:

"Tim Wescott" <tim@seemywebsite.now> wrote in message
news:tYmdnQq2qvI67xjWnZ2dnUVZ_omdnZ2d@web-ster.com...
Jon wrote:
I'm trying to wire a transfer circuit for a generator.

The generator will be located in the barn. The electrical service is at
the house. Two 120vac wires and a ground go to the barn. There is *one*
unused wire from the house to the barn I can use for a signal circuit.

When the power goes off at the house, I need to disconnect the service to
prevent backfeed and activate for generator power to both the house and
the barn. When the service power goes on I need to disconnect the
generator to avoid damaging it and restore normal service to the house
and the barn.

I have,

*one 240vac 60 amp dpdt mercury relay
*two 120vac 60 amp 3pdt relays.

Any ideas?

Jon Giffen

1: Dig a trench, lay some cable, do it 'right'.

2: Do an enormous science project, and plan on buying more relays.

One way I can think of to do this is to have the generator in the barn set
up to disconnect the _barn_ on power loss, then start itself up. Power the
one wire (against the 120V neutral reference) with what the generator
produces. Then up in the house, use the absence of street power and the
presence of generator power to switch off the street and onto the
generator.

You could complicate this further to automatically switch the generator
off, but you're already looking at a mad scientists dream; were I to do
this (I'd dig the @$%# trench) I'd just plan on _walking_ out to the barn
after the street lights come on and shutting things down manually.

If you're smart you'll check your local codes very carefully before
proceeding -- home generator setups that inadvertently apply power back to
the street can create very hazardous situations for line maintenance
folks, and power companies generally take a dim view of people winging
this sort of design. At the very least you'll need to use some
power-company-approved switchover device that locks out the generator when
you're on street power.

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com

Here's what I came up with:

120vac service lines 120vac
| |
| |
| | signal line
*------(coil A)------*--------------*
| | |
| | |
--- --- |
--- --- |
| A | A |
| | |
| | |
o--- house/barn -----o |
| | |
| | |
--- --- |
-/- -/- (coil B)
| B | B |
| | |
| | |
o-----generator------o ---
-
gnd

coil A 240vac contacts 200 amps N.O.
coil B 120vac contacts 100 amps N.C.

I don't need to turn the generator on right away. I just want to take the
guesswork out of turning the main breaker on and off every time the electric
goes out. Then I don't want to have to test if the power goes back on and I
can't tell. With this arrangement I can save trips back and forth to the
house and barn. If this works when the power goes off all we need to do is
go to the barn and fire up the generator.

I guess I could also add a generator kill switch off of coil B.

Let me know what you think.

Where do I find the relays?

Do you really thinK that the building inspector will let you connect
a home brew transfer switch to the grid?


--
Greed is the root of all eBay.

 

[ehsjr]

Jon wrote:

I'm trying to wire a transfer circuit for a generator.

The generator will be located in the barn. The electrical service is at
the house. Two 120vac wires and a ground go to the barn. There is
*one* unused wire from the house to the barn I can use for a signal
circuit.

When the power goes off at the house, I need to disconnect the service
to prevent backfeed and activate for generator power to both the house
and the barn. When the service power goes on I need to disconnect the
generator to avoid damaging it and restore normal service to the house
and the barn.

I have,

*one 240vac 60 amp dpdt mercury relay
*two 120vac 60 amp 3pdt relays.

Any ideas?

Jon Giffen

It's a no-go from the start. The electrical code requires you
to use a listed transfer switch. It *may* also prohibit you
from doing it yourself, even if you use listed equipment, and
require that the work be preformed by a licensed electrician.
Next, you need some large gauge wire from the generator to
the existing service if you will supply > 20 amps from the
generator. You need to do a voltage drop calculation based
on how much current you will allow to be drawn and the
distance the wire must run, to verify that you are using
large enough wire. Next, the code won't allow you to use
the same wires, regardless of transfer switches, for both
branch circuit wiring and feeder wiring.

What can you do yourself? Dig the trench, plan the system,
check the codes, make sure the licensed electrician (if
you use one) agrees with all that is to be done and who
is to do it, lay the wire between the buildings. Start
by making a *complete* list of *every* electrical device,
receptacle, appliance etc that is permanantly connected to
your wiring and identify which fuse/breaker controls
which circuit. Then figure out the absolute minimum that
you intend to run from the generator, and "layers" beyond
that. The "layers" could be something like: "minimum",
"convenient", "nice to have" and "full service". The more
you want, the more it'll cost.

If money is no object, the simplest is to hire a pro and
specify complete backup, automatic transfer and let him/her
specify the equipment. Unless you have a huge wallet,
that's probably a non-starter, too.

Ed

 

[Tim Watts]

Howard Eisenhauer <howarde@NOSPAMhfx.eastlink.ca>
wibbled on Wednesday 24 February 2010 22:37

1st question- Is the existing wiring out to the barn up to the job?
i.e. how many amps is your genset capable of suplying- 60 amps through
#10 ain't gonna cut it.

2nd- how many amps is your service rated for & how many can the genset
supply? A 60 A feed into a 200A service means you're gonna be
manually flipping brakers off anyhow...

3rd- Is there a seperate main service dissconnect from your breker
panel? If not you'll have to add noe between the meter & panel if you
want the xfer swittch to feed th whole house

4th- how understanding is the carrier for your fire insurance?
Jerry-rigged transfer switches using non-approved parts aside if
there's any problems at all with *any* of your wiring (whether you
were the last one to touch that particular part or not) that causes a
fire you can probably kiss your coverage goodbye

Personally I'd go with a type approved manual transfer switch, with a
seperate feed coming to it from the generator, feeding a "essential
services" sub panel .

I second that. Not sure about the paranoia re: insurance, but what *is* very
important, is that the OP does not under any circumstances back feed into
the utility supply. Otherwise, in a power outage, some poor linesman up a
pole gets a live line he thought was dead.

The IEE Wiring regs in the UK have something to say about local sources (be
it generator, UPS) - does the USA NEC code have regulations on this too?
IIRC, the NEC is available for free online (we have to pay for a copy of the
IEE Regs) so there's no excuse for not reading them.

I personally would go for a "proper" transfer switch. It's not just about
switching over - it's about maintaining required levels of mutual isolation
(eg contact separation distances etc) too.

Don't forget issues of earthing too - in the UK, we cannot count on the
utility earth (ground) in such a case, we must provision a local earth rod
for local generation with all that entails (eg correct use of RCD/GFCI).

Cheers

Tim

--
Tim Watts

Managers, politicians and environmentalists: Nature's carbon buffer.

 

[Jon]

"Michael A. Terrell" <mike.terrell@earthlink.net> wrote in message
news:4B85F8E8.6B645ED4@earthlink.net...

Jon wrote:

"Tim Wescott" <tim@seemywebsite.now> wrote in message
news:tYmdnQq2qvI67xjWnZ2dnUVZ_omdnZ2d@web-ster.com...
Jon wrote:
I'm trying to wire a transfer circuit for a generator.

The generator will be located in the barn. The electrical service is
at
the house. Two 120vac wires and a ground go to the barn. There is
*one*
unused wire from the house to the barn I can use for a signal circuit.

When the power goes off at the house, I need to disconnect the service
to
prevent backfeed and activate for generator power to both the house
and
the barn. When the service power goes on I need to disconnect the
generator to avoid damaging it and restore normal service to the house
and the barn.

I have,

*one 240vac 60 amp dpdt mercury relay
*two 120vac 60 amp 3pdt relays.

Any ideas?

Jon Giffen

1: Dig a trench, lay some cable, do it 'right'.

2: Do an enormous science project, and plan on buying more relays.

One way I can think of to do this is to have the generator in the barn
set
up to disconnect the _barn_ on power loss, then start itself up. Power
the
one wire (against the 120V neutral reference) with what the generator
produces. Then up in the house, use the absence of street power and
the
presence of generator power to switch off the street and onto the
generator.

You could complicate this further to automatically switch the generator
off, but you're already looking at a mad scientists dream; were I to do
this (I'd dig the @$%# trench) I'd just plan on _walking_ out to the
barn
after the street lights come on and shutting things down manually.

If you're smart you'll check your local codes very carefully before
proceeding -- home generator setups that inadvertently apply power back
to
the street can create very hazardous situations for line maintenance
folks, and power companies generally take a dim view of people winging
this sort of design. At the very least you'll need to use some
power-company-approved switchover device that locks out the generator
when
you're on street power.

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com

Here's what I came up with:

120vac service lines 120vac
| |
| |
| | signal line
*------(coil A)------*--------------*
| | |
| | |
--- --- |
--- --- |
| A | A |
| | |
| | |
o--- house/barn -----o |
| | |
| | |
--- --- |
-/- -/- (coil B)
| B | B |
| | |
| | |
o-----generator------o ---
-
gnd

coil A 240vac contacts 200 amps N.O.
coil B 120vac contacts 100 amps N.C.

I don't need to turn the generator on right away. I just want to take
the
guesswork out of turning the main breaker on and off every time the
electric
goes out. Then I don't want to have to test if the power goes back on
and I
can't tell. With this arrangement I can save trips back and forth to the
house and barn. If this works when the power goes off all we need to do
is
go to the barn and fire up the generator.

I guess I could also add a generator kill switch off of coil B.

Let me know what you think.

Where do I find the relays?


Do you really thinK that the building inspector will let you connect
a home brew transfer switch to the grid?

The grid is home brew. Otherwise we wouldn't need a generator for power

outages. The question is if I'm going to let their incompetence ruin my own
grid... and they're not getting any of my electricity, either.

--
Greed is the root of all eBay.

 

[Michael A. Terrell]

Jon wrote:

"Michael A. Terrell" <mike.terrell@earthlink.net> wrote in message
news:4B85F8E8.6B645ED4@earthlink.net...

Jon wrote:

"Tim Wescott" <tim@seemywebsite.now> wrote in message
news:tYmdnQq2qvI67xjWnZ2dnUVZ_omdnZ2d@web-ster.com...
Jon wrote:
I'm trying to wire a transfer circuit for a generator.

The generator will be located in the barn. The electrical service is
at
the house. Two 120vac wires and a ground go to the barn. There is
*one*
unused wire from the house to the barn I can use for a signal circuit.

When the power goes off at the house, I need to disconnect the service
to
prevent backfeed and activate for generator power to both the house
and
the barn. When the service power goes on I need to disconnect the
generator to avoid damaging it and restore normal service to the house
and the barn.

I have,

*one 240vac 60 amp dpdt mercury relay
*two 120vac 60 amp 3pdt relays.

Any ideas?

Jon Giffen

1: Dig a trench, lay some cable, do it 'right'.

2: Do an enormous science project, and plan on buying more relays.

One way I can think of to do this is to have the generator in the barn
set
up to disconnect the _barn_ on power loss, then start itself up. Power
the
one wire (against the 120V neutral reference) with what the generator
produces. Then up in the house, use the absence of street power and
the
presence of generator power to switch off the street and onto the
generator.

You could complicate this further to automatically switch the generator
off, but you're already looking at a mad scientists dream; were I to do
this (I'd dig the @$%# trench) I'd just plan on _walking_ out to the
barn
after the street lights come on and shutting things down manually.

If you're smart you'll check your local codes very carefully before
proceeding -- home generator setups that inadvertently apply power back
to
the street can create very hazardous situations for line maintenance
folks, and power companies generally take a dim view of people winging
this sort of design. At the very least you'll need to use some
power-company-approved switchover device that locks out the generator
when
you're on street power.

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com

Here's what I came up with:

120vac service lines 120vac
| |
| |
| | signal line
*------(coil A)------*--------------*
| | |
| | |
--- --- |
--- --- |
| A | A |
| | |
| | |
o--- house/barn -----o |
| | |
| | |
--- --- |
-/- -/- (coil B)
| B | B |
| | |
| | |
o-----generator------o ---
-
gnd

coil A 240vac contacts 200 amps N.O.
coil B 120vac contacts 100 amps N.C.

I don't need to turn the generator on right away. I just want to take
the
guesswork out of turning the main breaker on and off every time the
electric
goes out. Then I don't want to have to test if the power goes back on
and I
can't tell. With this arrangement I can save trips back and forth to the
house and barn. If this works when the power goes off all we need to do
is
go to the barn and fire up the generator.

I guess I could also add a generator kill switch off of coil B.

Let me know what you think.

Where do I find the relays?


Do you really thinK that the building inspector will let you connect
a home brew transfer switch to the grid?

The grid is home brew. Otherwise we wouldn't need a generator for power
outages. The question is if I'm going to let their incompetence ruin my own
grid... and they're not getting any of my electricity, either.

THEIR incompetence?


--
Greed is the root of all eBay.