alarm circuit question

[Jon]

I. GENERATOR TRANSFER CIRCUIT

The service wire is 000. I'm not even going to attempt a contactor for
that. I'd have to wire it hot and there's too much risk. All I'm going to
do is make a fail-safe circuit to protect the generator when the power goes
back on. It's only a 10kw generator so I'm using 120vac coil contactor with
contacts rated for 90amps. I'm going to use the spare wire from the house
to the barn to signal when the grid goes back on. That will open the
circuit and shut down the generator.

view in courier

service

120vac 120vac signal
o o o
| | |
o o------------*
\ main \ |
o o |
| | |
| house | |
| | |
| | |
| barn | (COIL)
--- --- | generator ignition
-/- N.C. -/- N.C.. | o
| | | |
o generator o | ---
--- --- N.O.
- |
gnd |
---
-
chassis

II. ALARM CLOCK.

I'm trying to wire a 120vac 150 mA fire alarm horn into the alarm of a
digital clock. I already did one with a fire bell. This clock is
different. It's a radio alarm clock, and the beeper alarm goes through the
speaker. I can't seem to get enough juice out of the speaker into the
transistor base for collecter-emitter flow to activate the 6vdc coil of my
relay with 6amp contacts. I'm using 10vdc from a circuit in the clock to
power the relay coil.

10vdc
o
|
*--------*
| |
R1=1k R2=1k
| |
| |
| |
\ |
T |-------*-----o red 120vac o
/ | |
| speaker 1.5vdc ---
| | --- N.O.
(coil) o black |
| buzzer
| |
--- ---
- -
clock common
gnd

I'm just a heavy sleeper and want something a little more lowder to wake me
up.

 

[Martin Riddle]

"Jon" <jon8338@peoplepc.com> wrote in message
news:Fpidnahd78CpfhTWnZ2dnUVZ_jSdnZ2d@earthlink.com...

I. GENERATOR TRANSFER CIRCUIT

The service wire is 000. I'm not even going to attempt a contactor
for that. I'd have to wire it hot and there's too much risk. All I'm
going to do is make a fail-safe circuit to protect the generator when
the power goes back on. It's only a 10kw generator so I'm using
120vac coil contactor with contacts rated for 90amps. I'm going to
use the spare wire from the house to the barn to signal when the grid
goes back on. That will open the circuit and shut down the generator.

view in courier

service

120vac 120vac signal
o o o
| | |
o o------------*
\ main \ |
o o |
| | |
| house | |
| | |
| | |
| barn | (COIL)
--- --- | generator ignition
-/- N.C. -/- N.C.. | o
| | | |
o generator o | ---
--- --- N.O.
- |
gnd |
---
-
chassis

The relay is relatively slow, 10-15ms response time. Worst case is a
total short with the gen, or a one AC cycle short with the gen. What
you need is a automatic transfer-switch. And you may need to switch L, N
and G if it’s a secondary branch. Spend the extra bucks and do it
right.

Cheers

 

[D Yuniskis]

Jon wrote:

I. GENERATOR TRANSFER CIRCUIT

The service wire is 000. I'm not even going to attempt a contactor for
that. I'd have to wire it hot and there's too much risk. All I'm going
to do is make a fail-safe circuit to protect the generator when the
power goes back on. It's only a 10kw generator so I'm using 120vac coil
contactor with contacts rated for 90amps. I'm going to use the spare
wire from the house to the barn to signal when the grid goes back on.
That will open the circuit and shut down the generator.

A potential candidate for the 2010 Darwin Awards?

 

[PeterD]

On Sat, 27 Feb 2010 22:30:00 -0500, "Jon" <jon8338@peoplepc.com>
wrote:

I. GENERATOR TRANSFER CIRCUIT

The service wire is 000. I'm not even going to attempt a contactor for
that. I'd have to wire it hot and there's too much risk.

No, you get an electrican who can interrupt the power to do the
connection(s).

All I'm going to
do is make a fail-safe circuit to protect the generator when the power goes
back on.

Neat trick, but that's no the issue. You need to prevent backfeeding
the power system even when the power is OFF.

It's only a 10kw generator so I'm using 120vac coil contactor with
contacts rated for 90amps. I'm going to use the spare wire from the house
to the barn to signal when the grid goes back on. That will open the
circuit and shut down the generator.

This absolutely, positively won't work the way you think it will. It
also will violate both safety and probably legal rules.

view in courier

service

120vac 120vac signal
o o o
| | |
o o------------*
\ main \ |
o o |
| | |
| house | |
| | |
| | |
| barn | (COIL)
--- --- | generator ignition
-/- N.C. -/- N.C.. | o
| | | |
o generator o | ---
--- --- N.O.
- |
gnd |
---
-
chassis

II. ALARM CLOCK.

I'm trying to wire a 120vac 150 mA fire alarm horn into the alarm of a
digital clock. I already did one with a fire bell. This clock is
different. It's a radio alarm clock, and the beeper alarm goes through the
speaker. I can't seem to get enough juice out of the speaker into the
transistor base for collecter-emitter flow to activate the 6vdc coil of my
relay with 6amp contacts. I'm using 10vdc from a circuit in the clock to
power the relay coil.

10vdc
o
|
*--------*
| |
R1=1k R2=1k
| |
| |
| |
\ |
T |-------*-----o red 120vac o
/ | |
| speaker 1.5vdc ---
| | --- N.O.
(coil) o black |
| buzzer
| |
--- ---
- -
clock common
gnd

I'm just a heavy sleeper and want something a little more lowder to wake me
up.

 

[PeterD]

On Sun, 28 Feb 2010 02:25:46 -0700, D Yuniskis
<not.going.to.be@seen.com> wrote:

Jon wrote:
I. GENERATOR TRANSFER CIRCUIT

The service wire is 000. I'm not even going to attempt a contactor for
that. I'd have to wire it hot and there's too much risk. All I'm going
to do is make a fail-safe circuit to protect the generator when the
power goes back on. It's only a 10kw generator so I'm using 120vac coil
contactor with contacts rated for 90amps. I'm going to use the spare
wire from the house to the barn to signal when the grid goes back on.
That will open the circuit and shut down the generator.

A potential candidate for the 2010 Darwin Awards?

Oh, no... Worse, a potential candidate for a manslaughter charge, and
10 years in jail for killing an electric lineman... And worse...

 

[Tim Watts]

Jon <jon8338@peoplepc.com>
wibbled on Sunday 28 February 2010 03:30

I. GENERATOR TRANSFER CIRCUIT

The service wire is 000. I'm not even going to attempt a contactor for
that. I'd have to wire it hot and there's too much risk.

Can you not get the supply made dead by requesting the supplier remove the
main fuse to your drop? I assume you have a main fuse (well, fuses)?

OK, I'm in England, but I went one better - I needed my line made dead for a
day to install a new breaker panel, so I tool the chance to add one of
these:

https://photos.dionic.net/v/public/bungalow/electrical/20090423180550.jpg.html

(Isolator switch, top right). It is actually the one that *some* electricity
suppliers fit, but not mine alas. Technically I'm not supposed to put it in
that box (belonging to the supplier) but I reached an friendly agreement
with the supply fitter.

At least now, I don't have to call them if I need to make my cables dead,
and lose power for the whole day (they pull the fuse in the morning, and
come back in the afternoon when they feel like). And they charge each
time...

All I'm going
to do is make a fail-safe circuit to protect the generator when the power
goes
back on. It's only a 10kw generator so I'm using 120vac coil contactor
with
contacts rated for 90amps. I'm going to use the spare wire from the house
to the barn to signal when the grid goes back on. That will open the
circuit and shut down the generator.

view in courier

service

120vac 120vac signal
o o o
| | |
o o------------*
\ main \ |
o o |
| | |
| house | |
| | |
| | |
| barn | (COIL)
--- --- | generator ignition
-/- N.C. -/- N.C.. | o
| | | |
o generator o | ---
--- --- N.O.
- |
gnd |
---
-
chassis

Is there a neutral there? I though you lot were 120-0-120 or does that vary?
Because you would want to isolate the neutral too. Also the use of the
utility earth (ground) is in question in the event of a power failure.

With all due respect, your proposal is *wrong* on many levels and I can't
believe I'm seeing this on an engineering forum. I don't know your codes,
though I'm fairly up on mine, but the basic tenants of good design are
pretty universal.

You need a break before make changeover device which will switch all lives
and the neutral at least, mechanically interlinked and with guaranteed
isolation (contact separation) of all conductors (probably including ground,
check the NEC). Note, other ways of achieving this could be to present key
circuits (eg heating supply to oil burner, lights) on a plug which is either
plugged into a suitably fused utility side socket, or unplugged and
replugged into another totally isolated socket fed by the generator. Indeed
this is an approach occasionally used in the UK where someone may which to
power the gas/oil heating system and maybe a lighting circuit from a small
genny. This would be the recognised poor mans method, though it is sound and
not automatic.

Anything else is a disaster waiting to happen. It is also not just about you
- you have obligations not to back feed your generated supply into an
otherwise dead utility supply and possibly kill an innocent third party
engineer.

Sorry to be harsh, but as you seem to persist in this dangerous, unnecessary
and cheapskate approach without any regard for even the most basic levels of
good design that would be obvious to a half clued up trainee electrician,
you need telling.

Don't be a cheap sod. Either don't do it, pay someone to do it or buy the
appropriate equipment and stop trying to use the crap in your garage spares
box.

And FFS go and read your bloody regulations man:

http://www.nfpa.org/aboutthecodes/AboutTheCodes.asp?DocNum=70&EditionID=238&cookie_test=1

Tim

--
Tim Watts

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

 

[Lil Red Riding In The Hoo]

On Sat, 27 Feb 2010 22:30:00 -0500, "Jon" <jon8338@peoplepc.com> wrote:

I. GENERATOR TRANSFER CIRCUIT

The service wire is 000. I'm not even going to attempt a contactor for
that. I'd have to wire it hot and there's too much risk. All I'm going to
do is make a fail-safe circuit to protect the generator when the power goes
back on. It's only a 10kw generator so I'm using 120vac coil contactor with
contacts rated for 90amps. I'm going to use the spare wire from the house
to the barn to signal when the grid goes back on. That will open the
circuit and shut down the generator.

view in courier

service

120vac 120vac signal
o o o
| | |
o o------------*
\ main \ |
o o |
| | |
| house | |
| | |
| | |
| barn | (COIL)
--- --- | generator ignition
-/- N.C. -/- N.C.. | o
| | | |
o generator o | ---
--- --- N.O.
- |
gnd |
---
-
chassis

II. ALARM CLOCK.

I'm trying to wire a 120vac 150 mA fire alarm horn into the alarm of a
digital clock. I already did one with a fire bell. This clock is
different. It's a radio alarm clock, and the beeper alarm goes through the
speaker. I can't seem to get enough juice out of the speaker into the
transistor base for collecter-emitter flow to activate the 6vdc coil of my
relay with 6amp contacts. I'm using 10vdc from a circuit in the clock to
power the relay coil.

10vdc
o
|
*--------*
| |
R1=1k R2=1k
| |
| |
| |
\ |
T |-------*-----o red 120vac o
/ | |
| speaker 1.5vdc ---
| | --- N.O.
(coil) o black |
| buzzer
| |
--- ---
- -
clock common
gnd

I'm just a heavy sleeper and want something a little more lowder to wake me
up.

Hook up a harmless shock box to the alarm circuit. Guaranteed efficacy.

 

[John Fields]

On Sat, 27 Feb 2010 22:30:00 -0500, "Jon" <jon8338@peoplepc.com> wrote:

I. GENERATOR TRANSFER CIRCUIT

The service wire is 000. I'm not even going to attempt a contactor for
that. I'd have to wire it hot and there's too much risk. All I'm going to
do is make a fail-safe circuit to protect the generator when the power goes
back on. It's only a 10kw generator so I'm using 120vac coil contactor with
contacts rated for 90amps. I'm going to use the spare wire from the house
to the barn to signal when the grid goes back on. That will open the
circuit and shut down the generator.

view in courier

service

120vac 120vac signal
o o o
| | |
o o------------*
\ main \ |
o o |
| | |
| house | |
| | |
| | |
| barn | (COIL)
--- --- | generator ignition
-/- N.C. -/- N.C.. | o
| | | |
o generator o | ---
--- --- N.O.
- |
gnd |
---
-
chassis

---
That circuit isn't fail-safe, it's fail-deadly.

Here:

Assume that mains power has failed, that the contactor's coil is no
longer energized, and as a consequence the contactor's contacts have
gone to their normally closed state.

Now assume that the generator starts and, once it has come up to speed,
is connected to your house wiring.

So far so good, but what happens when the service goes hot?

1. Until the contactor's contacts open, which takes time, the service
and the generator will be connected together (shorted) with no regard
to phase and there will very likely be some very nasty things happen.
2. And what about when someone's up on a pole fixing whatever it is that
caused the service to go down in the first place? Since you've
provided no isolation between the mains and your generator, whatever
the generator puts out will appear on the lines coming into your
house, which means all the other houses connected to the secondary of
the transformer you're connected to.

And worse, the service person won't know that the transformer
secondary isn't hot and... "Involuntary manslaughter" I think it's
called.

3. Your insurance company's going to have a big grin on their face when
the fire inspector finds your circuit.


Get yourself a licensed electrician, tell him what you want to do, and
pay the big bucks so you can sleep at night without having to worry
about burning up the kiddies.

II. ALARM CLOCK.

I'm trying to wire a 120vac 150 mA fire alarm horn into the alarm of a
digital clock. I already did one with a fire bell. This clock is
different. It's a radio alarm clock, and the beeper alarm goes through the
speaker. I can't seem to get enough juice out of the speaker into the
transistor base for collecter-emitter flow to activate the 6vdc coil of my
relay with 6amp contacts. I'm using 10vdc from a circuit in the clock to
power the relay coil.

10vdc
o
|
*--------*
| |
R1=1k R2=1k
| |
| |
| |
\ |
T |-------*-----o red 120vac o
/ | |
| speaker 1.5vdc ---
| | --- N.O.
(coil) o black |
| buzzer
| |
--- ---
- -
clock common
gnd

---
That doesn't look like it'll work but, even if it did, what's to keep
normal audio on the speaker from turning on the alarm?

JF

 

[Artemus]

"Jon" <jon8338@peoplepc.com> wrote in message
news:Fpidnahd78CpfhTWnZ2dnUVZ_jSdnZ2d@earthlink.com...
<snip>

I'm just a heavy sleeper and want something a little more lowder to wake me
up.

After your conviction for manslaughter due to your generator wiring scheme
you will have no problem waking up in prison.
Art

 

[ehsjr]

Jon wrote:

I. GENERATOR TRANSFER CIRCUIT

The service wire is 000. I'm not even going to attempt a contactor for
that. I'd have to wire it hot and there's too much risk. All I'm going
to do is make a fail-safe circuit to protect the generator when the
power goes back on. It's only a 10kw generator so I'm using 120vac coil
contactor with contacts rated for 90amps. I'm going to use the spare
wire from the house to the barn to signal when the grid goes back on.
That will open the circuit and shut down the generator.

<snip>

I'm just a heavy sleeper and want something a little more lowder to wake
me up.

Ok. Here is your wake up call.

The code requires that the transfer equipment make it
physically impossible for the generator to be connected
to the utility power lines UNDER ANY CONDITIONS.

Common sense requires that the transfer equipment make it
physically impossible for the generator to be connected
to the utility power lines UNDER ANY CONDITIONS.

Safety for personnel requires that the transfer equipment make it
physically impossible for the generator to be connected
to the utility power lines UNDER ANY CONDITIONS.

Safety for equipment requires that the transfer equipment make it
physically impossible for the generator to be connected
to the utility power lines UNDER ANY CONDITIONS.

USE PROPER TRANSFER EQUIPMENT. HAVE IT PROPERLY INSTALLED BY
A LICENSED ELECTRICIAN.

Ed

 

[RFI-EMI-GUY]

On 2/27/2010 10:30 PM, Jon wrote:

I. GENERATOR TRANSFER CIRCUIT

The service wire is 000. I'm not even going to attempt a contactor for
that. I'd have to wire it hot and there's too much risk. All I'm going
to do is make a fail-safe circuit to protect the generator when the
power goes back on. It's only a 10kw generator so I'm using 120vac coil
contactor with contacts rated for 90amps. I'm going to use the spare
wire from the house to the barn to signal when the grid goes back on.
That will open the circuit and shut down the generator.

view in courier

service

120vac 120vac signal
o o o
| | |
o o------------*
\ main \ |
o o |
| | |
| house | |
| | |
| | |
| barn | (COIL)
--- --- | generator ignition
-/- N.C. -/- N.C.. | o
| | | |
o generator o | ---
--- --- N.O.
- |
gnd |
---
-
chassis

II. ALARM CLOCK.

I'm trying to wire a 120vac 150 mA fire alarm horn into the alarm of a
digital clock. I already did one with a fire bell. This clock is
different. It's a radio alarm clock, and the beeper alarm goes through
the speaker. I can't seem to get enough juice out of the speaker into
the transistor base for collecter-emitter flow to activate the 6vdc coil
of my relay with 6amp contacts. I'm using 10vdc from a circuit in the
clock to power the relay coil.

10vdc
o
|
*--------*
| |
R1=1k R2=1k
| |
| |
| |
\ |
T |-------*-----o red 120vac o
/ | |
| speaker 1.5vdc ---
| | --- N.O.
(coil) o black |
| buzzer
| |
--- ---
- -
clock common
gnd

I'm just a heavy sleeper and want something a little more lowder to wake
me up.

If you have no contactor on the service feed, what are you doing to

prevent back feeding the generator onto the utility lines? Backfeeding
is dangerous to lineman working on what they believe to be de-energized
lines and is illegal.

--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"Š

"Use only Genuine Interocitor Parts" Tom Servo ;-P