capacitor bank for my home.

[KG4MXV]

I got my hands on 4 banks of 7 300uf 350V AC mylar capacitors and would like to use them for power factor correct on my home/shop.

When ever my HVAC start up or when I use my arc welder in the shop it makes the lights flicker in the house.
And it also affects my neighbor that is on the same tap of the transformer.

My question is how to connect them to my service.
SInce I do not want to use bleeder resistors (waists energy) I am going to use a contactor to separate them from the mains in the event of power failure using a under voltage relay to open the contactor if any of the phases drops below 90V.

Now the real question is to connect the neutral of the cap bank to ground or to leave it isolated?

 

[Grossel]

Hi.

A capacitor bank will probably not help for the flicker. Caps will help only if you have a problem with reactive currents and want to compensate for that.

What you need is is a rotating net stabilizer. An syncron motor with high inertia (or whatever you call huge rotation mass) on it's shaft. That way, the syncron motor can provide just enough power to prevent flash. Or at least minimize the flash effect.

That said, if you and your neighbour's houses is connected to the same transformer outpur I'd say it must be a poor transformer. So I think a better idea would be to talk about the issue to your local electrical provider.

Just for beinc curious, How many caps did you use to get that capacity?

 

[tronitech]

I don't know were you are based but home and small businesses are rarely penalised for poor power factor which is totally unrelated to your problem.

The HVAC and arc welder are pulling very high currents at switch on and I'm not sure your capacitor banks will help that much?

 

[Reloadron]

You do not use a bleeder resistor normally with AC mains power and capacitors used for power factor correction.

You do not mention the mains voltage? However, I suggest you

I have never seen power factor correction capacitor banks used for a residence. Generally for a residence, even a residence using the inductive loads you mention, it isn't all that practical. Also, I assume that the wire runs to the loads are adequate gauge wire? Meaning for example if you are in the US the wire gauge is in compliance with NEC code.

The link shows how it would be done for 240 VAC 60 Hz. power in the US. It also covers the formulas used.

Ron

 

[KG4MXV]

Actually each bank has 6 300uf and 1 100uF for a total of 1900uF
View attachment 64077
I plan on paralleling two banks per phase for 3800uf on each phase.
View attachment 64078

Hi.

A capacitor bank will probably not help for the flicker. Caps will help only if you have a problem with reactive currents and want to compensate for that.

What you need is is a rotating net stabilizer. An syncron motor with high inertia (or whatever you call huge rotation mass) on it's shaft. That way, the syncron motor can provide just enough power to prevent flash. Or at least minimize the flash effect.

That said, if you and your neighbour's houses is connected to the same transformer outpur I'd say it must be a poor transformer. So I think a better idea would be to talk about the issue to your local electrical provider.

Just for beinc curious, How many caps did you use to get that capacity?

 

[KG4MXV]

110V phase to N and 220 phase to phase.

 

[KG4MXV]

100A service to my shop a 60 foot run 0awg for each phase, ground and neutral.
I have called my utility provider to check the transformer and they said all was ok.
I know it was over kill but I rather be safe than sorry.
Plus the wire was free. ( left over from another job.)

 

[Reloadron]

If you want to place capacitors across the power coming in it is 240 VAC single phase or commonly called split phase in the US. It is actually single phase so there is no phase to phase. Anyway, if you want to place caps across it I see nothing wrong with doing it. For loads like AC or compressors running on 240 VAC the neutral is not used as a return. Not on my home system anyway. So yeah, place caps across the 240 VAC mains and between each leg of the split phase and neutral. The latter will only cover the 120 volt loads. While I do not see a gain it can't hurt I guess.

Ron

 

[ccurtis]

When ever my HVAC start up or when I use my arc welder in the shop it makes the lights flicker in the house.

I had this problem after my home A/C compressor was installed. It turned out that the connections where the wires from the pole transformer meet the lead-ins to the house were deteriorated. After repairing them, no flicker. That doesn't explain the issue with the neighbor though.

 

[KG4MXV]

Well My trans former is a ground unit and not on a pole. so I can't see the connections.
I do have a infra red imager but I can't open the transformer can to shoot the connections.

I will have the utility do another inspection since the last one was over a year ago

 

[tcmtech]

I plan on paralleling two banks per phase for 3800uf on each phase.

I want to be there when you hook that up!

3800 uf at 60 Hz will approximately equivalent to a .7 ohm short circuit per leg!

If light flicker from current draw is an issue this definitely wont help the situation! Odds are that high of pure capacitance load will put your main utility transformer way past its designed KVA capacity limits and burn it up in short order!

You need to do some serious reading and learning about AC power systems and how inductance and capacitance work before going any further.

 

[JimB]

If my quick calculations are correct, 380 μF across a 120volt 60hz supply will result in a current of 170amps flowing.

Why would you want to do this?
Do you have 170amps of inductive current to balance out? Probably not.

The only result that I can see is that there will be extra load on the line and transformer giving more volt drop due to the resistive losses of the line and transformer.

I hope that you are not thinking that this capacitor bank will act in the same way as the reservoir capacitor on a DC power supply?
It will not.
There is no way that a capacitor on an AC power line will provide any buffer against varying loads.

JimB

On edit:
It look like TCM and I are in agreement here.

 

[KG4MXV]

really?

 

[KG4MXV]

Ok, I will conduct a small scale experiment tomorrow.
I will connect only one capacitor @ 300uF with a 10A breaker.
And use a 100A contactor to close the circuit. safely from a distance.

if you are correct it will pop the breaker and no harm done.
and I will abandon the project.

I will admit my lack of knowledge of AC power circuits and will
take the above advice.

 

[tcmtech]

300 uf at 60 hz will be equivalent to about 8.8 ohms. At 120 volts it should pull about 13.6 amps.

If you have no real uses for them I would interested in buying them or trading for other things if the price is right.

Need any multi hundred amp 600 volt dual transistor blocks or 2400 - 3300 uf 350 VDC electrolytic capacitors?

 

[KG4MXV]

Then the question is what are you going to use them for.
I have 6 of the above banks but one of the capacitors has a large dent.
I have several IGBT's
But I Would love to get my hands an a decent sized UPS 10kva or larger minus the batteries (I have lots of batteries) To do this hack https://imgur.com/a/FJ3X9
Or a ATS switch.
Or a good weather station.
Name a price and I will see.
I will include the hardware. each post has a flat washer, split washer and 17mm nut.
The flat washer and nut are chrome plated brass.

Shipping is going to be kind of expensive.
I am in Raleigh NC.
Each bank weighs about 15 libs each.
I would have to put them on a pallet and freight it.



The above caps are from a retrofit kit for a 500KVA UPS that had shipping damage. (where the dent came from)_

 

[KG4MXV]

-----

 

[tcmtech]

I build rotary phase converters with them.

https://www.electro-tech-online.com/threads/3-phase-converter-schematic-miller-system.100563/

I did some checking and I think they are worth $6 a piece plus shipping to me and I dont need all the big base frameworks. Just the capacitors plus connection hardware.

One or two big boxs UPS or FedEx would be good enough for me.

Sorry I dont have any big UPS units. I do have a bunch of non functioning Trace and Heart Freedom inverters though. The boards are bad in them and not worth my time to repair.

https://www.electro-tech-online.com/threads/tcmtech-is-cleaning-out-the-shop.94134/

Just a thought.

 

[KG4MXV]

I don't know where you got that quote.
but I did a search on the part number and this is the link,
https://www.findchips.com/avail?part=b32362-a3307-J030

at the quantity pricing of 25 they are $208.39 ea

Given that I am not greedy and I offer no warranty even though these are new and unused.
I will offer $20.00 each. that is less than 10% of the retail.
If you only want to buy a few that is ok.

I will take paypal.
at the moment I am willing to let go of 5 300uF and 1 100uF I will sell for $80.00 including shipping.
as a good will gesture.

 

[KG4MXV]

tcmtech you are 100% correct.

When I applied 110Vac to the 300uF cap it was drawing 12amps .
Therefore this project is canned.
and will give you first dibs on the lot or how ever many you want to buy.

If you are going to buy over 7 of them I will have to add shipping.

I will wait to hear from you before posting them on the for sale area.
make an offer. ($6.00 a unit is too low sorry.)