Does it make sens to use a 60Hz AC line filter

[Piet de Pad]

Dear Electronic Enthusiast,
I'm working on a protection device against incoming bad electricity like spikes, under and over voltage and noise. Below low is a design I made. I would like to hear your ideas about this house protection device. In particular, my question "does it make sens to use a 60Hz Low pass filter at the entrance of a house" I would like to know more about.

To build this protection, I use four components

1. An Under and Overvoltage protection with time delays.
2. An 40A contactor
3. An AC Surge Protection Device, SPD
4. A 60 Hz low pas filter for 40Amp

The UV and OV protection in combination with the Contactor guarantees a stable AC voltage between two voltage levels. It also provides the time delays returning no normal operation after the occurrence of a UV or OV event.
The SPD shortcuts possible voltage spikes on the AC grid to earth.
The filter is a more complicated part. There are EMI filter for three-phase and single phase system exits, but not for split phase. Furthermore, I'm not convinced if an EMI filter at the main feed of a house is a good idea since most EMI is produced in the house and not coming in from the grid. It does block the EMI from the house into the grid. To block low frequent noise coming in from the grid and going out to the grid from the house a special designed low pass filter is needed and I haven't found them yet.

Let me know what you think and what you know.
Thanks.

 

[Easy peasy]

EMI filters - unless they are Rolls - Royce and oversized to keep the heat down, are not worth the money

Very large MOV's to neutral/earth are the best protection - usually 275Vac rated - get the big ones

as are MOV's from L-L - suitably sized.

good luck

 

[Piet de Pad]

EMI filters - unless they are Rolls - Royce and oversized to keep the heat down, are not worth the money

Very large MOV's to neutral/earth are the best protection - usually 275Vac rated - get the big ones

as are MOV's from L-L - suitably sized.

good luck

Thanks, I take your advice in consideration

 

[cupoftea]

TMOVs are your best bet as they tell you when they are about to die.
How do you know you have a mains transient problem?
Also, protection for lightning strikes is best from Phase to earth....(your local earth, which is where your house neutral connects to hopefully)

If lightning hits overhead wires, it will most likely raise all the phases and the neutral wire together....so they wont have an overvoltage with relation to each other....so phase-phase or phase-neutral movs arent that useful for lightning.

No website will tell you this, they will just laugh as we purchase their overexpensive transient protection offerings which are unsuitable.

The best general mains transient protector of all , for phase - neautral transients, is simply an electrolytic cap bank after a full wave bridge, hanging between phase - neutral....add a discharge resistor ...make it an active discharge resistor if you want to be real flashy. Protect it with a MOV if you want...and for most transients, that MOV wont be called into play.

Nobody has ever caught a mains transient on an oscilloscope yet. (by that i mean a mains transient which was shown to raise the voltage of an input HV electro cap (eg >47uF) bank up by more than a few tens of volts). So remember they are generally unheard of in built up areas, where loads of devices on the phases, quench any transient before it gets at all large in size.
Once worked in a co who released their new product into London with 2000 sales...after 2 years, and no failures, they decided to sell 30000 to west wales......all that 30000 failed. The product had essentially no mains transient protection. It had a 450V LR8 linear regulator after the mains rectifier and no post rectifier cap.(!). I had pleaded with them not to ship any of them...but after the success with 2000 in London, they were all "On the road to Damascus".

 

[D.A.(Tony)Stewart]

Every commercial ACDC power supply over perhaps 100W has a line filter due to the emissions requirements to attenuate the SMPS noise. In high volume the costs are low. Designing a residential filter for devices that do not need it (motors) makes the added cost unnecessary. I know that all electromechanical meters have a 6 kV arcgap built-in to withstand >> 10 kA.

You can define what is needed for protection based on the frequency of lightning transients near your residence, the cost of blown electronic replacements per decade, and the power requirements.

The energy and voltage attenuating LC filter you need is determined by the size of the CM and DM chokes accordingly with the L-L capacitor costs and the cheapest part being the MOV which has a limited lifetime energy absorption.