power off

robbymax

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when i switch from solar to grid and from grid to solar there is a delay for a split second and it is enough to switch off a TV or a computer and time clocks go off and it annoys the hell out of my Wife and i have got to do something, or get a lawyer.
now my idea is to put a bank of capacitors on the mains to the house to help bridge the gap will it work
 

OffGridInTheCity

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Some of the all-in-one units have UPS built-in. In my case, I'm individual component off-grid, so this happens twice a day when inverters come on in the morning and go off when the battery runs down. I use APC UPS(s) to take care of this issue - refurbished ones are pretty cheap on eBay.

In my case, I have *a lot* of appliances I wanted UPS'ed - so I bought some APC 3000(s) and ran 'UPS' sockets thru the house so that I could centralize the UPS function. In your case - if you only need 1 or 2 - then separate units at the TV etc would be more practical. For example a 1500 will support up to 1000watts or so - https://www.ebay.com/itm/203559860474?hash=item2f651cf8fa:g:dwYAAOSw2aRhDqdR - and they make them for all sizes, so a smaller one might do it for you.
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OffGridInTheCity

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don't just say YOU SERIOUS, if you have got something to say that can help lets hear it
Yea, re-reading this thread I see what you mean and I'm sorry it sounds harsh.
I think what's being expressed is that using capacitors on home main panel (240v@200a or 240v@100a) is not a workable idea as its more complicated than that and is what leads to UPSs (Uninterruptible Power Supplies). A UPS has capacitors for sure (as you expressed) but also a other stuff needed to make that idea work.

A whole house UPS is expensive when typically its a small % of the overall circuits that need UPS - which is why you don't see UPSs for Main Panels.
 

robbymax

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the power supply is not lost it is just coming from a different direction and they must not meet because you could be putting power into the mains and that is bad i just need it to happen faster so appliances dont see the change over and i see it has to happen on the load side
 

RCinFLA

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Caps on AC output will not do anything to help. It can degrade inverter load power factor that will increase peak AC current increasing losses in inverter and battery cables.

A grid connected hybrid inverter syncronizes to grid. For an all in one unit, even if powering from PV and/or batteries, the inverter will still remain synchronized to grid if it is available and presented to inverter input.

First thing is you must have grid source present for inverter to sync to. If you open AC breaker input to inverter you lose the sync and it can take several seconds for inverter to slowly phase sync again after AC is reconnected.

Beyond that, for a UPS type operation, the gap for switch over depends on time it takes for inverter to recognize AC has dropped and opening of relay to release from grid. This usually takes less then half cycle of AC input but can take up to one full cycle time. For UPS type operation the inverter must be running in parallel with grid continuously. You cannot use power saving mode that pulses on inverter periodically to check for AC loads.

Most devices plugged into AC will ride across a half cycle gap with their power supply DC filter caps. If you have a problem device you could add larger electrolytic filter cap to its DC power supply so it holds up longer.

When AC comes back on, the inverter it will start a slow phase re-alignment to grid before closing relay reconnecting to grid. Inverter will continue to provide power from batteries while the couple of seconds re-alignment to grid is going on.

The inverter must slowly align phase because you don't want a sudden phase shift on devices like AC motors in refrig or air conditioners.

The slow phase alignment correction can be a problem if inverter input is a regular 3600 rpm generator that has an unstable governor rpm control. The wobbling engine speed causes wobbling AC freq/phase at a rate the hybrid inverter cannot keep up with so it will just release connection from generator.
 
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robbymax

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my system is off grid when the battery bank gets low i manually switch to mains so inverter power and grid are not connected the system is near 20 years old so nothing is hybrid and nothing syncronizes the inverter stays on standby untill the battery bank is charged then i switch to inverter best this year was 19 days on solar but since May i have used Grid for about 8 day total. i have had a smart meter fitted so i can monitor my Grid use. i have a E7 charging system that i use over winter but it is not as cost efective as it used to be. I have never registered my system so i do not get FIT payments i want to be free to develop the system as i want and it has been my hobby, I shall beat this problem i may need somebodys help so any ideas would be helpfull but i still think the answer is in capacitors.
 

RCinFLA

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The small computer UPS units synchronize to grid so they can pick up load within half cycle.

Most new computer power supplies use a power factor correcting boost switcher stage between AC input rectifier and HV DC filter capacitor. These PF correction circuits do not like a sudden AC source phase shift. It can cause a high surge current in their power MOSFET and overvoltage the filter capacitor.
 

solar8484

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when i switch from solar to grid and from grid to solar there is a delay for a split second and it is enough to switch off a TV or a computer and time clocks go off and it annoys the hell out of my Wife and i have got to do something, or get a lawyer.
now my idea is to put a bank of capacitors on the mains to the house to help bridge the gap will it work

That's expected behavior for all line-interactive systems like yours. If you want guaranteed no reset then you need to put the devices on online double conversion UPS.
 

brewmatic

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I shall beat this problem i may need somebodys help so any ideas would be helpfull but i still think the answer is in capacitors.
Replace your transfer switch by a faster one. Capacitors can help only on DC circuits switching.
 

robbymax

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ok i am interested in the idea of a faster transfer switch any suggestions, i am useing a rotary switch and i try and switch it over as fast as possible to reduce the change over time but what else is available.
 

robbymax

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what about using a pair of contactors with DC coils and putting small capacitors on them to create a slight delay in de-energizeing the contactors, the capacitors could be very small and adjust them untill there is just enough delay
 
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robbymax

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south lincs UK
That's expected behavior for all line-interactive systems like yours. If you want guaranteed no reset then you need to put the devices on online double conversion UPS.
its the whole house we are talking about tv, radio, time clocks, computer, all drop out because of a split second in switch over
 

solar8484

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its the whole house we are talking about tv, radio, time clocks, computer, all drop out because of a split second in switch over

Yes, the whole house can drop out for a split second depending on where the AC voltage is when the switching happens. It's an inherent limitation. This is why datacenters use online double-conversion UPS in addition to line-interactive backup power systems to avoid reset of critical computers.
 

solar8484

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is it the transfer switch or the contactors i suspect both

Yes, it's both. Typical transfer switch/relays/contactors switching time can take 10ms+. Even fast ones take 3-5ms to switch and that's just not fast enough to guarantee no reset.
 

brewmatic

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Typical transfer switch/relays/contactors switching time can take 10ms+. Even fast ones take 3-5ms to switch and that's just not fast enough to guarantee no reset.

60Hz - > 16.6 ms period time. So 3-5ms switching time will not noticed by 99.99% of home equipment. But do not mix relay/contactor switching time with system transfer time (time between power failure and switching complete). Some system may be slow on power failure detection. Actually most of home electronic/electric devices will work without interruption if complete switching time is below 200-300ms.
 

OffGridInTheCity

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60Hz - > 16.6 ms period time. So 3-5ms switching time will not noticed by 99.99% of home equipment. But do not mix relay/contactor switching time with system transfer time (time between power failure and switching complete). Some system may be slow on power failure detection. Actually most of home electronic/electric devices will work without interruption if complete switching time is below 200-300ms.
I have several Go-Power and Progressive ATSs around my home for my off-grid solar system. None are fast-enough for continuous operation by computers, TVs/Tivo, K-Cup, iComfort (heat-pump thermostat) etc. UPS is needed based on my experience for electronic equipment that you want to maintain. I put the K-Cup on my UPS circuit to maintain the clock / auto-wake :). The microwave will just 'stop' - but its not very often we hit the ATS switch-overs in the middle of microwaving. Some things are OK (remember their settings / continue) such as my Reheems Hot-water heat-pump, refrigerators, and a Class-A UV controller for the rain-harvest system, and portable AC/heat-pump units.
 
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robbymax

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south lincs UK
I have several Go-Power and Progressive ATSs around my home for my off-grid solar system. None are fast-enough for continuous operation by computers, TVs/Tivo, K-Cup, iComfort (heat-pump thermostat) etc. UPS is needed based on my experience for electronic equipment that you want to maintain. I put the K-Cup on my UPS circuit to maintain the clock / auto-wake :). The microwave will just 'stop' - but its not very often we hit the ATS switch-overs in the middle of microwaving. Some things are OK (remember their settings / continue) such as my Reheems Hot-water heat-pump, refrigerators, and a Class-A UV controller for the rain-harvest system, and portable AC/heat-pump units.
do solid state relays operate faster than contactors brewmatic has stated that 3/5 ms is fast enough to work most things in the house i would settle for that
 
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