What to do about surges?

[Bobster.]

I hear talk about appliances being damaged by surges when power is restored after load shedding. Now I don't know how valid this is, and I don't doubt there's some component of trying to get money out of insurers, or trying to sell an appliance when one could be repaired. But I wonder. 

Maybe new appliances are more sensitive? I just bought a new washing machine to replace our old warhorse. Much was made of the special motor it has. That type of motor isn't so special now, but may have been a decade ago, and our warhorse is 20 something years old. 

The backed up circuits in my home have surge protection. This is fitted to the input and output of the inverter. But the washing machine is going to go into the outbuildings, which are not backed up. 

Should I unplug the washing machine when it's not in use? 

[hoohloc]

1 hour ago, Bobster. said:

I hear talk about appliances being damaged by surges when power is restored after load shedding. Now I don't know how valid this is, and I don't doubt there's some component of trying to get money out of insurers, or trying to sell an appliance when one could be repaired. But I wonder. 

Maybe new appliances are more sensitive? I just bought a new washing machine to replace our old warhorse. Much was made of the special motor it has. That type of motor isn't so special now, but may have been a decade ago, and our warhorse is 20 something years old. 

The backed up circuits in my home have surge protection. This is fitted to the input and output of the inverter. But the washing machine is going to go into the outbuildings, which are not backed up. 

Should I unplug the washing machine when it's not in use? 

I think this will be a good investment and will give you peace of mind incase your forget to unplug the washing machine. 

[Scorp007]

1 hour ago, Bobster. said:

I hear talk about appliances being damaged by surges when power is restored after load shedding. Now I don't know how valid this is, and I don't doubt there's some component of trying to get money out of insurers, or trying to sell an appliance when one could be repaired. But I wonder. 

Maybe new appliances are more sensitive? I just bought a new washing machine to replace our old warhorse. Much was made of the special motor it has. That type of motor isn't so special now, but may have been a decade ago, and our warhorse is 20 something years old. 

The backed up circuits in my home have surge protection. This is fitted to the input and output of the inverter. But the washing machine is going to go into the outbuildings, which are not backed up. 

Should I unplug the washing machine when it's not in use? 

Surges are for real. It does however make a big difference to the loads connected on the network close to you. 

If next to an industrial area there can be loads switched on after LS. Some areas suffer under and over voltage. Areas like where I live never have a supply outside of 210-238V that I have seen. The grid voltage on my inverter stats also don't show anything outside the values indicated. This is a far cry from other areas in the same munic or just south and north of us. 

Always a good practise to switch the wall socket of when not in use. Your appliance is a good example that can be off unless it is a wifi unit and you have a need to operate it from remote. 

I know of people that would for instance do the washing so that the cycle is complete when they step into the house. The same with a dishwasher. 

Microwaves with electronic displays are normally left on 24/7. They can get damaged by surges or lightning but those with mechanical turn knobs are less prone as all circuits are disconnected from the grid when off. Not to say they cannot get a surge but a far less likelihood. 

[Modina]

I absolutely agree with @Scorp007.

If there are power surges, then the voltage peaks will not be so high as to jump the contacts of an electro-mechanical switch in the off position.  So as a precaution, one can just switch off the wall-socket.  However, if you stay in Gauteng, or other areas with a high incidence of lighting, then I ABSOLUTELY recommend pulling out the plugs where possible.  I had some mayor electronics damage a few years ago when I was still in Pretoria.  The wall-plug feeding the PC, printer, etc. was switched off, but the lighting induced pulse just jumped right over those contacts and knocked out various power supplies.

I am glad not having to worry about lighting anymore.  If you have bad luck, you will loose your inverter to lighting doesn't matter how much protection or how expensive your inverter is.  Yes you can reduce your chances with protective gear, but you can never eliminate it completely.

BTW, @Bobster.  Your washing machine will have good mains filtering and reasonable surge protection.  The problem is, that we have LS three times a day.  That's about 1000 events per year.  A bit like playing Russian roulette and not knowing when to quit.  No designer would ever dream of having his equipment subjected to so much power cycling.

 

[Bobster.]

On 2023/03/11 at 8:01 PM, Scorp007 said:

If next to an industrial area there can be loads switched on after LS. Some areas suffer under and over voltage. Areas like where I live never have a supply outside of 210-238V that I have seen. The grid voltage on my inverter stats also don't show anything outside the values indicated. This is a far cry from other areas in the same munic or just south and north of us. 

I live in a residential area with no industry nearby. That I know of. Who knows what dark secrets lurk behind one's neighbours walls. 

What I do know is that voltage regularly hits 190 or less on restoration. On Friday it stayed south of 190 for over an hour. 

On 2023/03/11 at 8:01 PM, Scorp007 said:

Always a good practise to switch the wall socket of when not in use. Your appliance is a good example that can be off unless it is a wifi unit and you have a need to operate it from remote. 

The problem is that I can't control this. I have been quite reliable in switching off plugs in the room I use for my office, but here other folks are involved and they are not... as dedicated to the cause. 

There are two appliances in the outbuildings that I worry about. They now both are fitted with the devices that @hoohlocrecommended. It seems the most I can do.

I wonder about the pool pump that is on the same non-backed up DB. But surely that is not such a delicate device. 

I thought of getting a surge protector in that DB, but there isn't space, and I'm not much of... Ahem!.. Not Any kind of an electrician. The plug in devices will have to do for now. 

Just FYI, I have lightning protectors on both PV strings, and surge protectors on input & output of the inverter. At least I think that's the arrangement, there's definitely two of them. 

Thanks all for the answers. It's good to hear from folks who actually knkw what they're talking about. 

[WAP]

I got one similar to this installed in the DB. It has proven itself a couple of times already. You set the parameters and it cuts the eskom feed if the incoming voltages are below or above your settings.

 

[BritishRacingGreen]

2 minutes ago, WAP said:

I got one similar to this installed in the DB. It has proven itself a couple of times already. You set the parameters and it cuts the eskom feed if the incoming voltages are below or above your settings.

 

Availability / price and current rating? 

Edited March 13, 2023 by BritishRacingGreen

[Bobster.]

On 2023/03/11 at 8:01 PM, Scorp007 said:

If next to an industrial area there can be loads switched on after LS. Some areas suffer under and over voltage. Areas like where I live never have a supply outside of 210-238V that I have seen. The grid voltage on my inverter stats also don't show anything outside the values indicated. This is a far cry from other areas in the same munic or just south and north of us. 

This is interesting to me. If I am understanding correctly, these surges are local in nature. So maybe they don't originate in a substation.

Though, of course, if the grid supply wasn't being interrupted multiple times a day, surges would not be a very big deal.

Also is a low grid voltage an indicator of the likelihood of surges?

Edited March 13, 2023 by Bobster.

[Modina]

We talk about power surges but what does that mean?  Power surges could lead to under-voltage conditions (brownouts) or short duration transient over-voltage spikes.  Long term over-voltage is unlikely but not impossible to occur.

Most electronics use switch-mode power supplies and can handle large voltage variations without a problem.  In fact, more and more equipment is made with "universal" power supplies that is specified to run from 90VAC to 265VAC or thereabouts.  These supplies are made for world-wide distribution and can work from 110V 60Hz and 220V 50Hz regions out-of-the-box, without needing some form of configuration such as switch selection.

Electronics are mainly prone to transient voltage damage.

Motors are a rough inverse of the above.  They are less likely to get fried by transient voltage spikes, as long as these are not produced by excessively high voltages such as lighting strikes.  If a motor is already running and is subjected to a brownout, it is unlikely to get damaged.  The problem is with startup.  If utility is restored, the pool pump motor or fridge compressor now wants to start-up, the reduced supply voltage is too low for the motor to generate enough torque to get going.  It will now sit there stationary and hum.  There is no way for the motor to self-recover.  It would need a switch off and switch back on event.  The motor's fan will not run and the motor will overheat.  A fridge compressor obviously has no fan but they can suffer from vapor locks.

Note that the above are general comments.    There are many types of motors and not all will be effected.

Lastly, I just want to repeat what I said in a other thread about a week ago, regarding those suppression plugs.  I think they are overpriced and have very little value.  They use a single MOV (metal oxide varistor) and I go into detail as what I dislike about the internal construction of these plugs.  Basically a MOV is not ideal and the internal wiring is inadequate.

[Red Falcon]

Recently we experienced a surge in the area post loadshedding. 

Something wasn't right in the minu sub. All the houses on the street had 470v current coming through the mains. 

Charges and smaller items all blew. 

Some plug points burnt.  

And older fridges and freezers dead as well. 

[Chris Louw]

The CBI Astute smart controller can also be set to switch off when power surges or dips and switch on when power is normal again. Can only be used up 30 Amp. It can also be set for overloads. 

[wolfandy]

Most inverters will disconnect the grid if outside specified parameters

On my Sunsynk I felt that the standard parameter range was a bit too wide, so I manually set tighter limits

2 minutes ago, Chris Louw said:

The CBI Astute smart controller can also be set to switch off when power surges or dips and switch on when power is normal again

Same for the Sonoff POW range

I  actually have a 63A smart breaker right after my incoming mains and am running disconnected from the mains for most of the time. As a result, my inverter does not follow the voltage swings of the mains but rather provides 'clean' 230V to my house. Only when I see that my batteries might not be able to carry me through the night do I reconnect to the grid

[Chris Louw]

15 minutes ago, wolfandy said:

Most inverters will disconnect the grid if outside specified parameters

On my Sunsynk I felt that the standard parameter range was a bit too wide, so I manually set tighter limits

Same for the Sonoff POW range

I  actually have a 63A smart breaker right after my incoming mains and am running disconnected from the mains for most of the time. As a result, my inverter does not follow the voltage swings of the mains but rather provides 'clean' 230V to my house. Only when I see that my batteries might not be able to carry me through the night do I reconnect to the grid

Also use Sonoff Pow it is quite accurate. The CBI ASC also have a time delay that can be set for startup surges. 

[Bobster.]

3 hours ago, wolfandy said:

Most inverters will disconnect the grid if outside specified parameters

And mine does. I'm unconcerned about the backed up circuits. I am concerned about the non-backed up circuits, which really are just connected directly to the municipal supply.

One way to deal with this would be to put the sub-DB for the outbuildings onto the backed up side of the DB. That would mean the entire property would be backed up. Most days I would get away with this, but every now and then the extra load might cause me problems.

3 hours ago, wolfandy said:

On my Sunsynk I felt that the standard parameter range was a bit too wide, so I manually set tighter limits

Same for the Sonoff POW range

I  actually have a 63A smart breaker right after my incoming mains and am running disconnected from the mains for most of the time. As a result, my inverter does not follow the voltage swings of the mains but rather provides 'clean' 230V to my house. Only when I see that my batteries might not be able to carry me through the night do I reconnect to the grid

That's a neat solution. It could still leave me exposed, but not so often.

[WAP]

On 2023/03/13 at 6:39 AM, BritishRacingGreen said:

Availability / price and current rating? 

This is the one I have. Price was around R600 IIRC. Got it from my local Battery Centre, the guy does solar installations as well.

My installer installed the unit. If you google a bit you can find a few variations of the same thing.