electricalforum.nz

Hi,

Just a question about Array Switch Disconnector adjacent to the PCE.

I can't find the answer in either 5033:2012 or 5033:2021 (yet).

When connecting 2 arrays at the PCE (Each array will be connected to a separate MPPT input) is it acceptable to use 1x 4 pole Switch Disconnector, or do you have to use 2x 2pole switch disconnectors? Each array will be at a different voltage - ie. Array 1 @ 300VDC & Array 2 @ 200VDC - Im guessing 2 seperate SD reduces the risk of internal arcing between switch contacts.

I think it comes down to if the contacts of the DC Switch Disconnect can handle the current (rated operational current v rated operational voltage ) of each array using only two poles, the data sheet for the disconnect will confirm this.
Generally I see 4 poles used in series for each array, so two disconnects but if the inverter as a built in DC Switch Disconnect (as most do) and meets the requirements of 5033 clause 4.4.1.2 that's only one switch.
For the cost of the switches I cant see why installers wouldn't use a separate switch for each array as well as the inbuilt switch, if there is an issue with one array at least you can isolate that and keep the system going.

Agree separate devices for each array is preferable.
Just good design.

Also a question I've wondered.
Know that each MPPT connection is deemed a separate array and that each array requires one.

Question is is one device for two arrays suitable as you're asking and I don't have a definitive answer.

I advise clients for one for each array as I'd rather be on the safe side but it can be difficult to argue or not pass an RoI without a definite reference.

Hi Jamie, if you refer to the figures at the start of 5033, it clearly shows configuration for switch disconnects, that should help

What about 2.1.4.2?

"Each PV array shall have a switch-disconnector to provide isolation of the inverter. The provisions of multiple switch-disconnectors in
Clause 4.4.1.3 applies and a warning sign as required in Clause 5.5.2 shall be provided."

Or does having a shared one still consitute each array having one?

Sorry Jamie I am away at present so don’t have any references with me, but just off my head sharing is not the same as individual switches obviously
I still think as I mentioned above individual switches give the option of isolating an array if required, greater switching capabilities with the number of poles if they are limited eg can use 4 poles per array instead of 2

If it doesn't say "individual" or 'separate" then those concepts are not mandated.
Equally "shall have a" doesn't mean a common device can't be used.