PV VDC Exceeding 600v insulation rating?

[rezonatefreq907]

Is this a potential issue. The open voltage of the PV array exceeding the conductor insulation rating. Potential 1247 vdc with 600v conductor insulation rating. There are 6 PV arrays. Unknown as of yet what the max open circuit of each PV array is. Presume 1247 VDC? Could not acess the combiner. The conductor insulation is 600v printed right on it. Seems like an issue. Thoughts?

https://imgur.com/a/zmT1iST

 

[Jraef]

The utilization voltage rating of conductors is not the same as the voltage RESISTANCE of the conductor. The Voc of a PV only occurs at zero current, so that might relate to the VR rating of the conductor, but not the utilization voltage. It's RECOMMENDED that on PV arrays, when you do a megger test on the conductors (which is testing the VR), you do it at 2x the system voltage, so 1200V in this case.

UL 4703 for solar PV system conductors allows 600V PV systems to use 600V rated conductors. You can CHOOSE to use higher, and many people do, but it's not required.

 

[rezonatefreq907]

Makes sense 600V PV systems can use 600V rated conductors. PV max voltage of this system is 1267V as shown in pic 8 of 9. I believe this is the unloaded PV voltage. The system is online and working. Does not seem correct to have over 1200V on 600V conductors.

 

[ggunn]

Makes sense 600V PV systems can use 600V rated conductors. PV max voltage of this system is 1267V as shown in pic 8 of 9. I believe this is the unloaded PV voltage. The system is online and working. Does not seem correct to have over 1200V on 600V conductors.

It isn't, but where did you get the 1267V number?

 

[jaggedben]

The utilization voltage rating of conductors is not the same as the voltage RESISTANCE of the conductor. The Voc of a PV only occurs at zero current, so that might relate to the VR rating of the conductor, but not the utilization voltage. It's RECOMMENDED that on PV arrays, when you do a megger test on the conductors (which is testing the VR), you do it at 2x the system voltage, so 1200V in this case.

UL 4703 for solar PV system conductors allows 600V PV systems to use 600V rated conductors. You can CHOOSE to use higher, and many people do, but it's not required.

This is not helpful. Code requires the max voltage to be used to rate conductors. (690.7)

It isn't, but where did you get the 1267V number?

It's on a placard in one of the photos.

 

[jaggedben]

... Seems like an issue. Thoughts?

Definitely an issue assuming that marked DC voltage is at all close to correct.

Is this a potential issue. ...

No pun intended.

 

[Carultch]

Makes sense 600V PV systems can use 600V rated conductors. PV max voltage of this system is 1267V as shown in pic 8 of 9. I believe this is the unloaded PV voltage. The system is online and working. Does not seem correct to have over 1200V on 600V conductors.

You need 1500V of insulation in this case, which would in practice be 1kV/2kV PV wire. 2kV automatically includes compatibility with all systems less than 2kV, so it's redundant for 1kV to appear on the datasheet, but it's what you commonly see anyway. You don't get to add up the two voltages of both polarities, taking credit for them being in series. Instead, each wire independently, requires a rating for the maximum voltage across any pair of conductors, or any conductor and ground.

600V PV wire is meant for systems with a maximum (frigid open circuit) voltage of 600V or less. Usually, you see this when the corresponding AC voltage is 240V and less, e.g. residential.

 

[Eddie702]

From the pictures I saw the 600v rating but there also is a "2KV" on the wire.

What does that mean?

I don't claim to know anything about PV but does the voltage spike with no load connected to it?

 

[rezonatefreq907]

From the pictures I saw the 600v rating but there also is a "2KV" on the wire.

What does that mean?

I don't claim to know anything about PV but does the voltage spike with no load connected to it?

Good catch! I missed that since I quit looking after the 600V. Looks like they did use the correct wire then, presuming it is PV 2kV rated as indicated on picture 3 of 9. Below I attached a drawing schedule for the project that specifies 2kV PV wire. Thanks again, for the good eye. I am a newbie on this scale of a PV system @ 207kW PV, 250kW-480/277 VAC, 289kWh storage. This is a great group to learn from!

 

[Carultch]

From the pictures I saw the 600v rating but there also is a "2KV" on the wire.

What does that mean?

I don't claim to know anything about PV but does the voltage spike with no load connected to it?

Once you see the 2kV rating, you're good to go. The lower ratings on the wire are redundant, and likely just there to confirm backwards-compatiblity with previous standards.

Likely what happens, is that in order to pass the UL tests to label it as USE-2 wire, they can only test it for the USE-2 tests at 600V, because of a lack of UL testing procedures for higher voltages for that designation. That designation doesn't concern us anyway, since the PV wire rating governs. Historically, USE-2 was the wire type for what we currently use PV wire for today, which is likely why it has a backwards-compatible designation.

 

[Carultch]

I don't claim to know anything about PV but does the voltage spike with no load connected to it?

I wouldn't use the word spike to describe it, but yes, it does increase from what it is when there is a load. It's only a slight gain, rather than spiking to over twice as much voltage. It's typically about a 10% gain in voltage, from where they operate when feeding an inverter. Vmp under load, turns into Voc, at open circuit.