Sequence of protections in AC switchgear in a photovoltaic installation?

Question

Hello! When assembling a photovoltaic installation, I encountered two versions of protection connections in the AC switchgear (I omit the DC switchgear). Below I have shown both versions for AC, in the first one, the circuit goes to the circuit breaker and surge arrester, first from the inverter...

toolpusher · Answer

Read here: Link Also remember, if you already give a differential, type A min 100mA.

Jan_Werbinski · Answer

No difference. It's the SPD that is the fire risk. Do not buy. Pay more for Dehn or Phoenix Contact. Pay even more for a T1 spark gap.

toolpusher · Answer

I live in a city with earth lines and no overhead line close by. I have an old TN-C installation where the earth electrode is taken from steel pipes of the sewage system.
I also have an old box with old screwed fuses.
With such an installation, as I understand it, every impulse from the network burns electronics in the house, which has not happened so far, and I live for 30 years.
As I understand it, the requirement to install the OSD on the AC side is dictated by the standard or the art?
If it is to be of what class and what kind? Varistor or varistor + spark gap.
From what I have watched on the web, the vast majority of installations are based on VCX security. As I understand it, this is crap.
I used Dehn on the DC side in my installation, but such a VCX T1 + T2 (varistor) on the AC side due to the above.
This is a mistake?

Jan_Werbinski · Answer

You have a PV installation and probably expensive electronics at home. If you had carried out the risk analysis fairly, it would have been necessary to install LPS. If there is LPS, then you need a separation that is often difficult to achieve. Hence the T1. For T2, a varistor is enough, but T1 is just a spark gap.

Matuesz_99 · Answer

This RCD (SPD too) was only illustrative, usually it is 300mA And I have another question whether the use of RCDs is a standard requirement or common sense? Because I know a company that does not install RCDs in PV installations at all.

Cytro12 · Answer

Too much faith in security is also not healthy, the risk is always there, you just need to evaluate it and this is a subjective matter.

czesiu · Answer

In fact, it should be a type B RCD, because A will not turn off the direct current, and it is a protection to protect against a short circuit of the AC network with the DC installation in the event of damage to the transformerless inverter. RCD transformer inverters do not need, just like some transformerless inverters, equipped with a DC earth fault test system (something like an insulation control system in an IT network). Another matter where to install this RCD, in my opinion, it is better at the main switchboard than at the inverter. Installation in the switchgear would enable detection of damage (current leakage) of the power cable and disconnection of the faulty circuit (both during production and its absence), installation at the inverter, even when the RCD is triggered, does not disconnect the cable from the voltage.

toolpusher · Answer

Fronius recommends type A: Link

Jan_Werbinski · Answer

Lack of faith in security is dozens of times more unreasonable. Any single mother will prove it.

Cytro12 · Answer

Do you sell insurance because I hear this text every year? Do you think the more you spend it will be safer? This is not how it works, any mother will confirm it.

Jan_Werbinski · Answer

Each security measure works to some degree. For example, about 10 years ago, I bought a varistor SPD and they certainly paid off, despite the fact that they were not spark gap. I know how often I have had devices damaged before and after they were installed. This

Cytro12 · Answer

I spent many times less, no device was damaged, so in my opinion I am much ahead and I do not feel particularly threatened. As I wrote, the issue of risk valuation, since you set your risk high and adjusted the security, in your opinion it paid off, for me, despite the many times lower expenditure, it also paid off because I assessed the risk as accurately lower in the supplement. Hence the conclusion that there is no point in generalizing and unnecessarily costing in advance only according to the needs.

Jan_Werbinski · Answer

I have an overhead line, OLED TV servers, and a lot of electronics. The SPD cost less than 5%. I prefer to save on insurance. PZU is not a provider of insurance services, but a company that pays me dividends.

Sequence of protections in AC switchgear in a photovoltaic installation?

Post #1

Post #2

Post #3

Post #4

Post #5

Post #6

Post #7

Post #8

Post #9

Post #10

Post #11

Post #12

Post #13

Post #14

Topic summary