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Hi,
I want to consult:
which SPD from Citel to use for mppt 250/100 and input voltage 240V from PV (DC) ???
Is it suitable to use DS240S-220DC? Am I understanding correctly that if this SPD has value a Uc of 275V and if an overvoltage occurs, the SPD will leav flowing 275V into the MPPT?
Or should I rearrange the wiring of the PV field, to reduce the voltage up to 160V and use the SPD from Citel DS240S-130DC, which has a Uc of 180V?
Thanks for the guidance and help ;)
It is more about understanding why you want it used in your system.
By overvoltage in what scenario? This should not happen during normal production if array is sized correctly even with cloud edge effect. So the SPD is not meant to be sized for ''saving" equipment from that.
If now you have lightning and that is what you are aiming at protecting wiring fires and dangerous voltages to humans in the system. Then even the one that start clamping voltage at 275v will be fine.
You can use the lower one, but then you are consuming it during normal use if you size your PV VOC higher than the 180v and it will need to be replaced more often if during normal use it is being triggered.
Hi,
I want to use it as a protection against inductive overvoltage during storms, not as overvoltage protection oversized PV :) (that no sense, to do that).
I am not sure about that Uc=275V in this case can voltage damage the mppt, thats the point of my question.
I understan it good, that the voltage reachedd over 275V (Uc) will be grounded, or voltage over (Un=220V)
What I want to do: cables are 20m long from PV to MPPT.
After 10m I want to insert SPD (Un=500V, Up=4kV) and before MPPT (next 10m) SPD (Un220 Uc275 Up0.9kV or Un130,Uc180,Up0.5kV)
Slightly above is fine.
See this article here, its about the simplest explanation i have found.
The mppt can possibly be damaged by overvoltage that much is stated in the manuals. But it is transient. And that being said from experience, we live in a high strike area and have not had an issue to date and have a much higher than max voltage rated SPD.
Thanks for advice. Basically, I'll summarize it both according to the link and according to what I write, so it is ideal to use an SPD that has a Uc voltage as close as possible to the max. voltage PV input for MPPT.
Ideal = not higher :)
Thanks.
The key is operating voltages.
So your VOC is the key since the PV does not operate above that. Even if the equipment can do 250v max you are not likely to be running the VOC there.
But sometimes supplies are what they are the 275v will have to do at the end of the day.
Remember that while we don't want our equipment to be killed, it is people/life (and to some extent this includes the wiring) we need to protect above all else.
