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kenryan
Joined: 20 Oct 2009
Posts: 426
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 Posted: Wed Dec 23, 2020 6:16 am Post subject: automatic switch |
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This is for a hangar home that is under construction, so it is relevant 
I am planning a small solar/generator powered emergency electrical system. Three solar panels, a 4800 watt-hour lithium battery, charge controller and an inverter/charger.Â
It's function will be to run necessary equipment (boiler, unit heater, well pump, refrigerator/freezer) in the event of a power outage.Â
I have experience with systems like this from having built three campers. But this is different in that I would like to have a switch that automatically detects when the power goes off, and switches things over to the alternate system.
I know such switches exist, but I know nothing about them -- how they operate, how to choose one, how to wire one into the system, etc. I would appreciate any info people might have.
Ken Ryan
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peteruss2(at)hotmail.com
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| Posted: Wed Dec 23, 2020 7:56 am Post subject: automatic switch |
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Try looking at IGBT devices ..maybe checkout DIGAKEY PRODUCTS
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Ceengland
Joined: 11 Oct 2020
Posts: 386
Location: MS
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| Posted: Wed Dec 23, 2020 8:17 am Post subject: automatic switch |
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On 12/23/2020 8:11 AM, Ken Ryan wrote:
| Quote: | This is for a hangar home that is under construction, so it is
relevant
I am planning a small solar/generator powered emergency electrical
system. Three solar panels, a 4800 watt-hour lithium battery, charge
controller and an inverter/charger.
It's function will be to run necessary equipment (boiler, unit heater,
well pump, refrigerator/freezer) in the event of a power outage.
I have experience with systems like this from having built three
campers. But this is different in that I would like to have a switch
that automatically detects when the power goes off, and switches
things over to the alternate system.
I know such switches exist, but I know nothing about them -- how they
operate, how to choose one, how to wire one into the system, etc. I
would appreciate any info people might have.
Ken Ryan
Hi Ken,
|
At their simplest, they are DPDT relays with common to load, normally
closed terminals tied to the backup generator and normally open
terminals tied to the line. Line power activates the coil of the relay.
When line power 'drops', the relay switches to the backup terminals.
I've got a backup generator on my house with the mfgr's purpose-built
switch; more complex in that it manages the generator startup and (IIRC)
waits to apply the load until the generator is up to speed. My setup is
complicated a bit (OK, a lot) because I actually have 3 phase power to
my house, and a standard single phase generator. I have some 220V single
phase loads that have one leg on the 3rd phase, so I have to also switch
one leg of a 3 phase load to one of the single phase legs when the
generator comes on line. For this, I used a relatively inexpensive
automatic switch similar to this:
https://www.ebay.com/itm/373107679744?_trkparms=ispr%3D1&amdata=enc%3AAQAFAAACQBaobrjLl8XobRIiIML1V4Imu%252Fn%252BzU5L90Z278x5ickkd%252F0I%252BERpYfmzqCvv7sUYEiMnF2axAEl9q2lSCIlkYaYVHn3mJ6Wa5wEMvmDn8uxTMxj32yK3bDxTkgR4V9edhGXnRvcQ0vUf%252F93bvTeb%252FXHCtlg3u8RUWERU5%252FH0mqbicjj13f0qSPcudz4EzH3b4BHBQVAkU9eQV8rT4%252FR7c33dX8Cgzc7JCEasmNKLnaYUCCJY52pfjr8K1fz23LQiXAJ%252BE7EZmHwX6M0QKbZLkynKTAgD%252F7pwKwPfudNsCEGUOoaljGVx5x1neFVG2sqOItY0ASop8TY25HVbBo4TnBNr5oGg2l7HLvWwU2h10XBWuGAbZceqPsRMahjxbsAstgc3cy2HKbQSB8u4Qwc20%252F5Bi8J5s7x2BXdBDKjCkEMwhXL2B3MPlNKH15cUioOkGz8A1SKEnDlG4evpmD1a%252BVfw0wRfplwi5%252FsKD4slLo7vluRxfES7mJtX%252BmbuRsd1v5bPV7s8NcEt1QBK3gtbpVluwdyjtscnf1zv9XJossDhZ%252FkTBLrdCOCKM75s0FMz72qZrrTkpg%252F6a5WNP8rQXa6v6jgKNxHgf%252BosKXaSmmKPAOg2XEbJ6TGGHA1ZbfU2Q7%252BPFKoknYYCi04jPR3V8Gi4c%252BFpn2ICvume959kr%252BS9r35h088j%252FPzJA745eko0wRGNxezMNVf55Dc1zSuuvByAknxZz4YyfpMfsIY5LhYgAqBlTio99SI2mPzW8rIUbw%253D%253D%7Ccksum%3A3731076797441dfdcb105a744a9faf66816ba7733d1e%7Campid%3APL_CLK%7Cclp%3A3268220&chn=ps&norover=1&mkevt=1&mkrid=711-117182-37290-0&mkcid=2&itemid=373107679744&targetid=1068323853350&device=c&mktype=pla&googleloc=9013952&poi=&campaignid=10456336033&mkgroupid=106723176427&rlsatarget=aud-622524042478:pla-1068323853350&abcId=2146001&merchantid=6296724&gclid=CjwKCAiA8ov_BRAoEiwAOZogwbEA9XSqJRMLH163QnMuK2YJhtJ-ClTlNXpnOjryz8AOak3lzDW8lBoCpXEQAvD_BwE
Markings are not in English, and sorting out how to connect the device
took some time and effort.
Note that I'm so cheap I'll waste a week to save a few dollars, and I
also have a reasonable history around electrical 'stuff' (my father was
an electrician his whole career, and I ran an electronics repair company
before being hired by USPS as an electronics tech). If you have a solid
foundation in electrical/electronic principles and you're willing to put
in the effort, you can probably DIY, but if you're uncomfortable with
the idea, it might be time to call an electrician.
Does that help?
--
This email has been checked for viruses by Avast antivirus software.
https://www.avast.com/antivirus
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nuckolls.bob(at)aeroelect
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| Posted: Wed Dec 23, 2020 8:26 am Post subject: automatic switch |
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| Quote: |
I know such switches exist, but I know nothing about them -- how they operate, how to
choose one, how to wire one into the system, etc. I would appreciate any info people might have.
Ken Ryan |
Lots of products out there but not difficult to build
The 'transfer' device is simply a two-pole, double-throw
contactor that connects loads to EITHER ac mains OR
inverter.
You'll need a control system with some simple logic.
(1) Transfer to INVERTER is asserted when (a)
battery voltage is higher than some minimum
-AND- (b) when AC mains power is not present.
(2) Inverter system is in a 'relaxed maintenance'
mode any time AC mains power is present.
(3) you might need a timer with xx milliseconds
delay from time AC mains fails until transfer
is asserted. Needed only if inverter doesn't gracefully
grunt a load during startup. Not likely but
should be confirmed.
There are dozens of off-the-shelf product that
would accomplish this task. Check out websites
that target off-grid, homepower systems.
Bob . . .
Un impeachable logic: George Carlin asked, "If black boxes
survive crashes, why don't they make the whole airplane
out of that stuff?"
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ashleysc(at)broadstripe.n
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| Posted: Wed Dec 23, 2020 8:29 am Post subject: automatic switch |
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Hi Ken;
They're available and called (appropriately) "automatic transfer switch." They're generally used to transfer from utility current to emergency generator current, but will work equally well in your application. There are also "manual transfer switches," if you want to save some money.
Cheers! Stu.
From: "Ken Ryan" <keninalaska(at)gmail.com>
To: aeroelectric-list(at)matronics.com
Sent: Wednesday, December 23, 2020 6:11:44 AM
Subject: AeroElectric-List: automatic switch
This is for a hangar home that is under construction, so it is relevant
I am planning a small solar/generator powered emergency electrical system. Three solar panels, a 4800 watt-hour lithium battery, charge controller and an inverter/charger.
It's function will be to run necessary equipment (boiler, unit heater, well pump, refrigerator/freezer) in the event of a power outage.
I have experience with systems like this from having built three campers. But this is different in that I would like to have a switch that automatically detects when the power goes off, and switches things over to the alternate system.
I know such switches exist, but I know nothing about them -- how they operate, how to choose one, how to wire one into the system, etc. I would appreciate any info people might have.
Ken Ryan
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kenryan
Joined: 20 Oct 2009
Posts: 426
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| Posted: Wed Dec 23, 2020 9:24 am Post subject: automatic switch |
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Thanks everyone. I think I understand how to do it now. Perhaps those with knowledge of these systems can check my work:
a) battery (3600 watt-hours) lithium
b) connect solar (1100 watts) through solar charge control to battery
c) connect 240v (output) inverter/battery charger to battery
d) install an automatic transfer switch to house electrical system (power all loads)
e) connect the output of the inverter to the transfer switch (where normally a generator would be connected)
f) run a 110 volt outlet to the battery charger that is built into the inverter
g) if battery gets low, connect 3kw 110v Honda generator to the inverter/charger to charge the battery (when solar is insufficient)
h) in the summer, when there is plenty of power, I could cut the power from the grid and run off solar.
When the power goes out, the transfer switch cuts connection to the grid and makes connection to the inverter. When generator is connected to inverter/charger, generator runs loads and recharges battery. When power from grid returns, the transfer switch cuts the connection to the inverter and makes the connection to the grid.
So I guess any generic automatic transfer switch should work, right?
On Wed, Dec 23, 2020 at 7:34 AM Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
| Quote: | | Quote: |
I know such switches exist, but I know nothing about them -- how they operate, how to
choose one, how to wire one into the system, etc. I would appreciate any info people might have.
Ken Ryan |
 Lots of products out there but not difficult to build
 The 'transfer' device is simply a two-pole, double-throw
 contactor that connects loads to EITHER ac mains OR
 inverter.
 You'll need a control system with some simple logic.
 (1) Transfer to INVERTER is asserted when (a)
     battery voltage is higher than some minimum
     -AND- (b) when AC mains power is not present.
 (2) Inverter system is in a 'relaxed maintenance'
     mode any time AC mains power is present.
 (3) you might need a timer with xx milliseconds
     delay from time AC mains fails until transfer
     is asserted. Needed only if inverter doesn't gracefully
     grunt a load during startup. Not likely but
     should be confirmed.
 There are dozens of off-the-shelf product that
 would accomplish this task. Check out websites
 that target off-grid, homepower systems.
Â
 Bob . . .
 Un impeachable logic: George Carlin asked, "If black boxes
 survive crashes, why don't they make the whole airplane
 out of that stuff?"
|
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Ceengland
Joined: 11 Oct 2020
Posts: 386
Location: MS
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| Posted: Wed Dec 23, 2020 11:17 am Post subject: automatic switch |
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Your problem will be that you're not talking about enough 'grunt' from the solar/battery/inverter system, to support the whole house. I had similar issues with my 12KW 'whole house' generator; it won't support both AC units, electric oven, etc while lighting the house. If you do some googling of how smaller generating systems are set up, there will be a main panel which feeds the majority of loads. One breaker in the main panel will feed the transfer switch, which will then feed a sub-panel. That sub-panel then feeds the essential circuits. The 'off the shelf' switches made for whole house backup generators often incorporate the sub-panel in the same box with the transfer switch. This one (1st random link I hit) is very similar to the one used with my 12KW system:
https://www.zoro.com/generac-automatic-transfer-switch-100a-gray-rxg16eza1/i/G5258373/
Charlie
On 12/23/2020 11:18 AM, Ken Ryan wrote:
| Quote: | Thanks everyone. I think I understand how to do it now. Perhaps those with knowledge of these systems can check my work:
a) battery (3600 watt-hours) lithium
b) connect solar (1100 watts) through solar charge control to battery
c) connect 240v (output) inverter/battery charger to battery
d) install an automatic transfer switch to house electrical system (power all loads)
e) connect the output of the inverter to the transfer switch (where normally a generator would be connected)
f) run a 110 volt outlet to the battery charger that is built into the inverter
g) if battery gets low, connect 3kw 110v Honda generator to the inverter/charger to charge the battery (when solar is insufficient)
h) in the summer, when there is plenty of power, I could cut the power from the grid and run off solar.
When the power goes out, the transfer switch cuts connection to the grid and makes connection to the inverter. When generator is connected to inverter/charger, generator runs loads and recharges battery. When power from grid returns, the transfer switch cuts the connection to the inverter and makes the connection to the grid.
So I guess any generic automatic transfer switch should work, right?
On Wed, Dec 23, 2020 at 7:34 AM Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
| Quote: | | Quote: |
I know such switches exist, but I know nothing about them -- how they operate, how to
choose one, how to wire one into the system, etc. I would appreciate any info people might have.
Ken Ryan |
 Lots of products out there but not difficult to build
 The 'transfer' device is simply a two-pole, double-throw
 contactor that connects loads to EITHER ac mains OR
 inverter.
 You'll need a control system with some simple logic.
 (1) Transfer to INVERTER is asserted when (a)
     battery voltage is higher than some minimum
     -AND- (b) when AC mains power is not present.
 (2) Inverter system is in a 'relaxed maintenance'
     mode any time AC mains power is present.
 (3) you might need a timer with xx milliseconds
     delay from time AC mains fails until transfer
     is asserted. Needed only if inverter doesn't gracefully
     grunt a load during startup. Not likely but
     should be confirmed.
 There are dozens of off-the-shelf product that
 would accomplish this task. Check out websites
 that target off-grid, homepower systems.
Â
 Bob . . .
 Un impeachable logic: George Carlin asked, "If black boxes
 survive crashes, why don't they make the whole airplane
 out of that stuff?"
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kenryan
Joined: 20 Oct 2009
Posts: 426
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| Posted: Wed Dec 23, 2020 11:43 am Post subject: automatic switch |
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I would manage this by limiting my usage during a power outage. Everything is available, but everything is not used.
On Wed, Dec 23, 2020 at 10:23 AM Charlie England <ceengland7(at)gmail.com (ceengland7(at)gmail.com)> wrote:
| Quote: | Your problem will be that you're not talking about enough 'grunt' from the solar/battery/inverter system, to support the whole house. I had similar issues with my 12KW 'whole house' generator; it won't support both AC units, electric oven, etc while lighting the house. If you do some googling of how smaller generating systems are set up, there will be a main panel which feeds the majority of loads. One breaker in the main panel will feed the transfer switch, which will then feed a sub-panel. That sub-panel then feeds the essential circuits. The 'off the shelf' switches made for whole house backup generators often incorporate the sub-panel in the same box with the transfer switch. This one (1st random link I hit) is very similar to the one used with my 12KW system:
https://www.zoro.com/generac-automatic-transfer-switch-100a-gray-rxg16eza1/i/G5258373/
Charlie
On 12/23/2020 11:18 AM, Ken Ryan wrote:
| Quote: | Thanks everyone. I think I understand how to do it now. Perhaps those with knowledge of these systems can check my work:
a) battery (3600 watt-hours) lithium
b) connect solar (1100 watts) through solar charge control to battery
c) connect 240v (output) inverter/battery charger to battery
d) install an automatic transfer switch to house electrical system (power all loads)
e) connect the output of the inverter to the transfer switch (where normally a generator would be connected)
f) run a 110 volt outlet to the battery charger that is built into the inverter
g) if battery gets low, connect 3kw 110v Honda generator to the inverter/charger to charge the battery (when solar is insufficient)
h) in the summer, when there is plenty of power, I could cut the power from the grid and run off solar.
When the power goes out, the transfer switch cuts connection to the grid and makes connection to the inverter. When generator is connected to inverter/charger, generator runs loads and recharges battery. When power from grid returns, the transfer switch cuts the connection to the inverter and makes the connection to the grid.
So I guess any generic automatic transfer switch should work, right?
On Wed, Dec 23, 2020 at 7:34 AM Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
| Quote: | | Quote: |
I know such switches exist, but I know nothing about them -- how they operate, how to
choose one, how to wire one into the system, etc. I would appreciate any info people might have.
Ken Ryan |
 Lots of products out there but not difficult to build
 The 'transfer' device is simply a two-pole, double-throw
 contactor that connects loads to EITHER ac mains OR
 inverter.
 You'll need a control system with some simple logic.
 (1) Transfer to INVERTER is asserted when (a)
     battery voltage is higher than some minimum
     -AND- (b) when AC mains power is not present.
 (2) Inverter system is in a 'relaxed maintenance'
     mode any time AC mains power is present.
 (3) you might need a timer with xx milliseconds
     delay from time AC mains fails until transfer
     is asserted. Needed only if inverter doesn't gracefully
     grunt a load during startup. Not likely but
     should be confirmed.
 There are dozens of off-the-shelf product that
 would accomplish this task. Check out websites
 that target off-grid, homepower systems.
Â
 Bob . . .
 Un impeachable logic: George Carlin asked, "If black boxes
 survive crashes, why don't they make the whole airplane
 out of that stuff?"
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nuckolls.bob(at)aeroelect
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| Posted: Wed Dec 23, 2020 12:07 pm Post subject: automatic switch |
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At 01:38 PM 12/23/2020, you wrote:
| Quote: | | I would manage this by limiting my usage during a power outage. Everything is available, but everything is not used. |
I have a manual system where I use the
feeder to the a/c compressor as a means
for getting power into the house from
and outside generator.
I manually transfer the a/c feeder over
to the generator. I also have to open
the a/c mains breaker out on my meter box.
I open breakers to all 240v appliances
to avoid inadvertent overloads.
This arrangement with a 5500W generator
will allow us to run more than adequate
lights, freezer, refrigeration, furnaces,
etc. I've got a natural gas conversion kit
yet to install on on the generator so as
to do away with storing large amounts of
gasoline and then having to periodically
top off the tank.
This whole system was crafted from
off-the-shelf materials from Harbor
Freight and the N.G. Conversion kit
for under $700. Best yet, the generator
remains portable for the occasional off-site
power needs.
Bob . . .
Un impeachable logic: George Carlin asked, "If black boxes
survive crashes, why don't they make the whole airplane
out of that stuff?"
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Ceengland
Joined: 11 Oct 2020
Posts: 386
Location: MS
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| Posted: Wed Dec 23, 2020 12:11 pm Post subject: automatic switch |
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|
That's fine, but if it's 'automatic', that implies that it can switch over and begin consuming power off the backup(s) whether you're there to 'load shed' or not. Just something to think about.
On Wed, Dec 23, 2020 at 1:52 PM Ken Ryan <keninalaska(at)gmail.com (keninalaska(at)gmail.com)> wrote:
| Quote: | I would manage this by limiting my usage during a power outage. Everything is available, but everything is not used.
On Wed, Dec 23, 2020 at 10:23 AM Charlie England <ceengland7(at)gmail.com (ceengland7(at)gmail.com)> wrote:
| Quote: | Your problem will be that you're not talking about enough 'grunt' from the solar/battery/inverter system, to support the whole house. I had similar issues with my 12KW 'whole house' generator; it won't support both AC units, electric oven, etc while lighting the house. If you do some googling of how smaller generating systems are set up, there will be a main panel which feeds the majority of loads. One breaker in the main panel will feed the transfer switch, which will then feed a sub-panel. That sub-panel then feeds the essential circuits. The 'off the shelf' switches made for whole house backup generators often incorporate the sub-panel in the same box with the transfer switch. This one (1st random link I hit) is very similar to the one used with my 12KW system:
https://www.zoro.com/generac-automatic-transfer-switch-100a-gray-rxg16eza1/i/G5258373/
Charlie
On 12/23/2020 11:18 AM, Ken Ryan wrote:
| Quote: | Thanks everyone. I think I understand how to do it now. Perhaps those with knowledge of these systems can check my work:
a) battery (3600 watt-hours) lithium
b) connect solar (1100 watts) through solar charge control to battery
c) connect 240v (output) inverter/battery charger to battery
d) install an automatic transfer switch to house electrical system (power all loads)
e) connect the output of the inverter to the transfer switch (where normally a generator would be connected)
f) run a 110 volt outlet to the battery charger that is built into the inverter
g) if battery gets low, connect 3kw 110v Honda generator to the inverter/charger to charge the battery (when solar is insufficient)
h) in the summer, when there is plenty of power, I could cut the power from the grid and run off solar.
When the power goes out, the transfer switch cuts connection to the grid and makes connection to the inverter. When generator is connected to inverter/charger, generator runs loads and recharges battery. When power from grid returns, the transfer switch cuts the connection to the inverter and makes the connection to the grid.
So I guess any generic automatic transfer switch should work, right?
On Wed, Dec 23, 2020 at 7:34 AM Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
| Quote: | | Quote: |
I know such switches exist, but I know nothing about them -- how they operate, how to
choose one, how to wire one into the system, etc. I would appreciate any info people might have.
Ken Ryan |
 Lots of products out there but not difficult to build
 The 'transfer' device is simply a two-pole, double-throw
 contactor that connects loads to EITHER ac mains OR
 inverter.
 You'll need a control system with some simple logic.
 (1) Transfer to INVERTER is asserted when (a)
     battery voltage is higher than some minimum
     -AND- (b) when AC mains power is not present.
 (2) Inverter system is in a 'relaxed maintenance'
     mode any time AC mains power is present.
 (3) you might need a timer with xx milliseconds
     delay from time AC mains fails until transfer
     is asserted. Needed only if inverter doesn't gracefully
     grunt a load during startup. Not likely but
     should be confirmed.
 There are dozens of off-the-shelf product that
 would accomplish this task. Check out websites
 that target off-grid, homepower systems.
Â
 Bob . . .
 Un impeachable logic: George Carlin asked, "If black boxes
 survive crashes, why don't they make the whole airplane
 out of that stuff?"
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fly4grins(at)gmail.com
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| Posted: Thu Dec 24, 2020 4:07 am Post subject: automatic switch |
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| Quote: | That's fine, but if it's 'automatic', that implies that it can switch over
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| Quote: | and begin consuming power off the backup(s) whether you're there to 'load
shed' or not. Just something to think about. Â
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I have been contemplating some of these issues off and on for a while. One option would be to put all essential loads on one phase of the main panel. Have adequate wiring to a heavy duty 120v receptacle on a dedicated breaker on that phase. When the power fails, trip the main breaker and plug a portable generator into the dedicated receptacle. No load shedding required, just about as simple as can be, and probably not more than $20 in parts.
FWIW-
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yellowduckduo(at)gmail.co
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| Posted: Thu Dec 24, 2020 4:31 am Post subject: automatic switch |
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While these manual schemes work well somebody should mention that they
are illegal almost everywhere due to the risk of back feeding power to
the utility and electrocuting a lineman by mis handling the main
breaker. It happens which is why a double throw main breaker
arrangement is mandated.
Ken
On 24/12/2020 7:01 AM, GLEN MATEJCEK wrote:
| Quote: | >That's fine, but if it's 'automatic', that implies that it can switch
over
>and begin consuming power off the backup(s) whether you're there to 'load
>shed' or not. Just something to think about.
I have been contemplating some of these issues off and on for a
while. One option would be to put all essential loads on one phase of
the main panel. Have adequate wiring to a heavy duty 120v receptacle
on a dedicated breaker on that phase. When the power fails, trip the
main breaker and plug a portable generator into the dedicated
receptacle. No load shedding required, just about as simple as can
be, and probably not more than $20 in parts.
FWIW-
|
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nuckolls.bob(at)aeroelect
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| Posted: Thu Dec 24, 2020 5:36 am Post subject: automatic switch |
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At 06:27 AM 12/24/2020, you wrote:
| Quote: | --> AeroElectric-List message posted by: C&K <yellowduckduo(at)gmail.com>
While these manual schemes work well somebody should mention that they are illegal almost everywhere due to the risk of back feeding power to the utility and electrocuting a lineman by mis handling the main breaker. It happens which is why a double throw main breaker arrangement is mandated. |
Yup, that's why there is a check-list for
transitions between mains and generator . . .
but failure to disconnect ac mains would
result in immediate operation of the generator's
breakers.
Bob . . .
Un impeachable logic: George Carlin asked, "If black boxes
survive crashes, why don't they make the whole airplane
out of that stuff?"
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kenryan
Joined: 20 Oct 2009
Posts: 426
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| Posted: Thu Dec 24, 2020 6:06 am Post subject: automatic switch |
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The essential loads that I need to run are boiler, unit heater, well pump and refrigerator/freezer and hangar door. Given that this is at least 90% of the total amperage and a good percentage of the circuits, I believe powering the whole building is what makes sense. And I definitely agree that the system must not allow for feedback to the grid through operator error.Â
Ken
On Thu, Dec 24, 2020 at 4:41 AM Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
| Quote: | At 06:27 AM 12/24/2020, you wrote:
| Quote: | --> AeroElectric-List message posted by: C&K <yellowduckduo(at)gmail.com (yellowduckduo(at)gmail.com)>
While these manual schemes work well somebody should mention that they are illegal almost everywhere due to the risk of back feeding power to the utility and electrocuting a lineman by mis handling the main breaker. It happens which is why a double throw main breaker arrangement is mandated. |
 Yup, that's why there is a check-list for
 transitions between mains and generator . . .
 but failure to disconnect ac mains would
 result in immediate operation of the generator's
 breakers.
 Bob . . .
 Un impeachable logic: George Carlin asked, "If black boxes
 survive crashes, why don't they make the whole airplane
 out of that stuff?"
|
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finn.usa(at)gmail.com
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| Posted: Fri Dec 25, 2020 9:10 am Post subject: automatic switch |
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Once I made a relatively low cost manual transfer switch using a 100 amp panel.
In the two top places I mounted two 2-pole 100A breakers side by side with a small alum bar and two screws connecting the two breaker handles.
One of the holes on the alum bar was actually slotted so you could turn off both breakers if wanted. But the bar made it impossible to turn on both breakers at the same time. One of the breakers was connected to the 12 KWh generator, the other to a breaker (strictly speaking not needed if lugs available after main breaker) in the main panel. That 100 amp panel became the sub panel for essential stuff: lights, one A/C and computers.
Sure was a lot cheaper than the $500 to $1,000 manual transfer switches available at the time. I think the cost of the two 100A breakers and panel was less than $100.
Finn
On 12/24/2020 9:01 AM, Ken Ryan wrote:
| Quote: | The essential loads that I need to run are boiler, unit heater, well pump and refrigerator/freezer and hangar door. Given that this is at least 90% of the total amperage and a good percentage of the circuits, I believe powering the whole building is what makes sense. And I definitely agree that the system must not allow for feedback to the grid through operator error.Â
Ken
On Thu, Dec 24, 2020 at 4:41 AM Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
| Quote: | At 06:27 AM 12/24/2020, you wrote:
| Quote: | --> AeroElectric-List message posted by: C&K <yellowduckduo(at)gmail.com (yellowduckduo(at)gmail.com)>
While these manual schemes work well somebody should mention that they are illegal almost everywhere due to the risk of back feeding power to the utility and electrocuting a lineman by mis handling the main breaker. It happens which is why a double throw main breaker arrangement is mandated. |
 Yup, that's why there is a check-list for
 transitions between mains and generator . . .
 but failure to disconnect ac mains would
 result in immediate operation of the generator's
 breakers.
 Bob . . .
 Un impeachable logic: George Carlin asked, "If black boxes
 survive crashes, why don't they make the whole airplane
 out of that stuff?"
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Ceengland
Joined: 11 Oct 2020
Posts: 386
Location: MS
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| Posted: Fri Dec 25, 2020 12:03 pm Post subject: automatic switch |
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Yep; some breaker panel mfgrs make optional slides to do exactly that. In our area, about 10Â miles out of the biggest town in the state, we tend to lose power if it rains anywhere in the county. I went 'full auto' because the spousal unit wasn't going to learn how to the multi-step switching required to keep our air conditioner functional on the generator; also wanted the switch to happen if we were out of town for a few days. Didn't want to lose freezer/fridge stuff.
I also spent a long time waiting for craigslist deals on the generator & automatic transfer switch/subpanel (as mentioned, I'm way too cheap to buy new).
Charlie
On 12/25/2020 10:58 AM, Finn Lassen wrote:
| Quote: | Once I made a relatively low cost manual transfer switch using a 100 amp panel.
In the two top places I mounted two 2-pole 100A breakers side by side with a small alum bar and two screws connecting the two breaker handles.
One of the holes on the alum bar was actually slotted so you could turn off both breakers if wanted. But the bar made it impossible to turn on both breakers at the same time. One of the breakers was connected to the 12 KWh generator, the other to a breaker (strictly speaking not needed if lugs available after main breaker) in the main panel. That 100 amp panel became the sub panel for essential stuff: lights, one A/C and computers.
Sure was a lot cheaper than the $500 to $1,000 manual transfer switches available at the time. I think the cost of the two 100A breakers and panel was less than $100.
Finn
On 12/24/2020 9:01 AM, Ken Ryan wrote:
| Quote: | The essential loads that I need to run are boiler, unit heater, well pump and refrigerator/freezer and hangar door. Given that this is at least 90% of the total amperage and a good percentage of the circuits, I believe powering the whole building is what makes sense. And I definitely agree that the system must not allow for feedback to the grid through operator error.Â
Ken
On Thu, Dec 24, 2020 at 4:41 AM Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
| Quote: | At 06:27 AM 12/24/2020, you wrote:
| Quote: | --> AeroElectric-List message posted by: C&K <yellowduckduo(at)gmail.com (yellowduckduo(at)gmail.com)>
While these manual schemes work well somebody should mention that they are illegal almost everywhere due to the risk of back feeding power to the utility and electrocuting a lineman by mis handling the main breaker. It happens which is why a double throw main breaker arrangement is mandated. |
 Yup, that's why there is a check-list for
 transitions between mains and generator . . .
 but failure to disconnect ac mains would
 result in immediate operation of the generator's
 breakers.
 Bob . . .
 Un impeachable logic: George Carlin asked, "If black boxes
 survive crashes, why don't they make the whole airplane
 out of that stuff?"
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n233ee(at)gmail.com
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| Posted: Fri Dec 25, 2020 2:15 pm Post subject: automatic switch |
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Our utility in S Indiana ‘grounds’ all wiring before any work is done. Although our solar system has the required disconnects etc they really are not needed. It does increase the down time since all the grounds need to be removed before applying power, it will save lives. This method probably is growing and will be used everywhere soon. [I am a retired electrician]
| Quote: | On Dec 25, 2020, at 2:13 PM, Charlie England <ceengland7(at)gmail.com> wrote:
 Yep; some breaker panel mfgrs make optional slides to do exactly that. In our area, about 10 miles out of the biggest town in the state, we tend to lose power if it rains anywhere in the county. I went 'full auto' because the spousal unit wasn't going to learn how to the multi-step switching required to keep our air conditioner functional on the generator; also wanted the switch to happen if we were out of town for a few days. Didn't want to lose freezer/fridge stuff.
I also spent a long time waiting for craigslist deals on the generator & automatic transfer switch/subpanel (as mentioned, I'm way too cheap to buy new).
Charlie
On 12/25/2020 10:58 AM, Finn Lassen wrote:
| Quote: | Once I made a relatively low cost manual transfer switch using a 100 amp panel.
In the two top places I mounted two 2-pole 100A breakers side by side with a small alum bar and two screws connecting the two breaker handles.
One of the holes on the alum bar was actually slotted so you could turn off both breakers if wanted. But the bar made it impossible to turn on both breakers at the same time. One of the breakers was connected to the 12 KWh generator, the other to a breaker (strictly speaking not needed if lugs available after main breaker) in the main panel. That 100 amp panel became the sub panel for essential stuff: lights, one A/C and computers.
Sure was a lot cheaper than the $500 to $1,000 manual transfer switches available at the time. I think the cost of the two 100A breakers and panel was less than $100.
Finn
On 12/24/2020 9:01 AM, Ken Ryan wrote:
| Quote: | The essential loads that I need to run are boiler, unit heater, well pump and refrigerator/freezer and hangar door. Given that this is at least 90% of the total amperage and a good percentage of the circuits, I believe powering the whole building is what makes sense. And I definitely agree that the system must not allow for feedback to the grid through operator error.
Ken
On Thu, Dec 24, 2020 at 4:41 AM Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
| Quote: | At 06:27 AM 12/24/2020, you wrote:
| Quote: | --> AeroElectric-List message posted by: C&K <yellowduckduo(at)gmail.com (yellowduckduo(at)gmail.com)>
While these manual schemes work well somebody should mention that they are illegal almost everywhere due to the risk of back feeding power to the utility and electrocuting a lineman by mis handling the main breaker. It happens which is why a double throw main breaker arrangement is mandated. |
Yup, that's why there is a check-list for
transitions between mains and generator . . .
but failure to disconnect ac mains would
result in immediate operation of the generator's
breakers.
Bob . . .
Un impeachable logic: George Carlin asked, "If black boxes
survive crashes, why don't they make the whole airplane
out of that stuff?"
|
|
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kenryan
Joined: 20 Oct 2009
Posts: 426
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| Posted: Sat Dec 26, 2020 6:19 am Post subject: automatic switch |
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Thanks Stu. I've been studying these switches. One thing I have not been able to discover is how much current an automatic utility disconnect transfer switch uses. I would like to know the answer to that question both for the grid connection and for the "generator" connection. I have found some spec sheets, but none of them have this information. I have learned that my application is probably what is referred to as utility-utility (rather than utility-generator) Another question I have not been able to answer is whether an automatic switch that is designed for a generator (which includes provisions for starting and stopping a generator) can be used in a utility-utility application, without a lot of hassle.
On Sat, Dec 26, 2020 at 1:12 AM <ashleysc(at)broadstripe.net (ashleysc(at)broadstripe.net)> wrote:
| Quote: | Hi Ken;
They're available and called (appropriately) "automatic transfer switch." They're generally used to transfer from utility current to emergency generator current, but will work equally well in your application. There are also "manual transfer switches," if you want to save some money.
Cheers!  Stu.
From: "Ken Ryan" <keninalaska(at)gmail.com (keninalaska(at)gmail.com)>
To: aeroelectric-list(at)matronics.com (aeroelectric-list(at)matronics.com)
Sent: Wednesday, December 23, 2020 6:11:44 AM
Subject: automatic switch
This is for a hangar home that is under construction, so it is relevant
I am planning a small solar/generator powered emergency electrical system. Three solar panels, a 4800 watt-hour lithium battery, charge controller and an inverter/charger.Â
It's function will be to run necessary equipment (boiler, unit heater, well pump, refrigerator/freezer) in the event of a power outage.Â
I have experience with systems like this from having built three campers. But this is different in that I would like to have a switch that automatically detects when the power goes off, and switches things over to the alternate system.
I know such switches exist, but I know nothing about them -- how they operate, how to choose one, how to wire one into the system, etc. I would appreciate any info people might have.
Ken Ryan
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