weressl
Esteemed Member
Sure there is, the DC transformer........:smile:
short circuit amp readings
- Thread starter smramsey
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Sure there is, the DC transformer........:smile:
Originally Posted by iwire
Different situation entirely, there is no transformer here.
Given that this is probably a 100% generating facility, all solar panels will add to the SCA less their respecitve cable impedance. This must be calculated using either IEEE or IEC standards. The utility company probably wants to know how to protect their system given a fault at the generating solar site. As I stated earlier, these computations must be performed by an engineer educated in short circuit studies or using a competent software program of which there are only a few capable of accurately performing SCA values. Site testing is not an option, using the rated SCA of any device is also not an option, and using one's opinion is also not an option.
Sorry to be so frank but the resulting SCA values are very important to not only protect the generator's site but also the utility lines and the workers if exposed to the short via arc flash and arc blast.
Different situation entirely, there is no transformer here.
Given that this is probably a 100% generating facility, all solar panels will add to the SCA less their respecitve cable impedance. This must be calculated using either IEEE or IEC standards. The utility company probably wants to know how to protect their system given a fault at the generating solar site. As I stated earlier, these computations must be performed by an engineer educated in short circuit studies or using a competent software program of which there are only a few capable of accurately performing SCA values. Site testing is not an option, using the rated SCA of any device is also not an option, and using one's opinion is also not an option.
Sorry to be so frank but the resulting SCA values are very important to not only protect the generator's site but also the utility lines and the workers if exposed to the short via arc flash and arc blast.
- Location
- Massachusetts
Have you worked with utility interactive PV systems?
The total Isc of my 50 KW system is under 200 amps, not a drop in the bucket compared to the utility fault current.
I will be frank as well, it is not complicated and it does not take an EE to figure it out.
To iwire...
Have you worked with utility interactive PV systems? - Yes
The total Isc of my 50 KW system is under 200 amps - Good for you. However, does HIS system exactly match yours?
I will be frank as well, it is not complicated and it does not take an EE to figure it out.
That's some statement...I'm afraid to ask how you computed your SCA values.
Have you worked with utility interactive PV systems? - Yes
The total Isc of my 50 KW system is under 200 amps - Good for you. However, does HIS system exactly match yours?
I will be frank as well, it is not complicated and it does not take an EE to figure it out.
That's some statement...I'm afraid to ask how you computed your SCA values.
weressl
Esteemed Member
Well Pilgrim, brain surgery is just the same as taking a bullet out....... You heat up a knife, a bigune, waste some good bourbon where it gone in and just dug in.....we don't need no stinkin' brain surgeons.....
- Location
- Massachusetts
I did not, it was not required and is not required with most of these systems.
- Location
- Massachusetts
Well Pilgrim, brain surgery is just the same as taking a bullet out....... You heat up a knife, a bigune, waste some good bourbon where it gone in and just dug in.....we don't need no stinkin' brain surgeons.....
We are not talking about brain surgery, we are talking about putting a band aid on a boo boo.
Sorry to let you in on this but EEs are not needed for every electrical project.
weressl
Esteemed Member
We are not talking about brain surgery, we are talking about putting a band aid on a boo boo.
Sorry to let you in on this but EEs are not needed for every electrical project.
..and you are qualified by what and according to whom, to determine what needs engineering attention or not?
You tend to comment on issues whose depth you seem to be completely unaware of.
Could you please list for me the short circuit impedance contribution parameters? Could you please explain to me if short circuiting a solar panel is a destructive, a damaging or a harmless test?
gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
090114-1123 EST
Here are two references:
http://howto.altenergystore.com/Lib...aracteristics-of-Solar-Panels-PV-Modules/a87/
This one shows some I-V curves.
http://www1.eere.energy.gov/solar/printable_versions/current_voltage.html
I did not find any plots here, and they have circular references.
Apparently the solar inverters are designed to operate at the maximum power point if needed. The knee of the curve is this point. Thus, if you have DC data from the solar panel while operating, it is operating at the maximum power point, has maximum incident solar energy, is clean of snow or dirt, and you can plot the DC current, then the peak point of this curve is moderately close to the short circuit capability of the collector under the conditions of operation.
iwire's link to the real time and historical data of his 50 KW system should provide a useful measure of the DC short circuit current of the array, but it seems this function is not currently turned on.
DC short circuit current capability of the array does not tell you what is the AC short circuit output of the inverter. This is a function of the inverter design and that information would need to come from the manufacturer.
.
Here are two references:
http://howto.altenergystore.com/Lib...aracteristics-of-Solar-Panels-PV-Modules/a87/
This one shows some I-V curves.
http://www1.eere.energy.gov/solar/printable_versions/current_voltage.html
I did not find any plots here, and they have circular references.
Apparently the solar inverters are designed to operate at the maximum power point if needed. The knee of the curve is this point. Thus, if you have DC data from the solar panel while operating, it is operating at the maximum power point, has maximum incident solar energy, is clean of snow or dirt, and you can plot the DC current, then the peak point of this curve is moderately close to the short circuit capability of the collector under the conditions of operation.
iwire's link to the real time and historical data of his 50 KW system should provide a useful measure of the DC short circuit current of the array, but it seems this function is not currently turned on.
DC short circuit current capability of the array does not tell you what is the AC short circuit output of the inverter. This is a function of the inverter design and that information would need to come from the manufacturer.
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