Author Topic: MNSPD 115 DC  (Read 177 times)

ralova_24

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MNSPD 115 DC
« on: April 25, 2020, 02:34:03 PM »
Hello Gentlemen!

Can I use MNSPD 115 DC in 150Vdc? Is it safe?

Thank you
Rick

ClassicCrazy

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Re: MNSPD 115 DC
« Reply #1 on: April 25, 2020, 09:27:16 PM »
The spec sheet for SPD says  to use the next size up SPD for voltage you asked about.
I don't know about your safe question . My guess is it won't be unsafe just won't be effective for the job it is supposed to do.
But that is just a guess about safety as I am not expert on it.
Take a look here
http://www.midnitesolar.com/pdfs/SPD_Installation_Manual.pdf

Larry


system one
Classic 150 , 5s4p  Kyocera 135watt , 12s Soneil 2v 540amp lead crystal for 24v pack , Outback 3524 inverter
system two
Classic 150 ,5s 135 watt Kyocero , 16s Calb 100AH LiFePO4 , Outback VFX 3648 inverter
system three
Midnite KID MPPT 24 DC in to  12 volt AGM batterie

ralova_24

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Re: MNSPD 115 DC
« Reply #2 on: April 30, 2020, 01:30:48 PM »
I guess MNSPD115 DC can be used in 150Vdc circuit/system voltage since the Maximum Continuous Operating Voltage (MCOV) stated in spec sheet is 180Vdc...///thanks Larry

Rick

Vic

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Re: MNSPD 115 DC
« Reply #3 on: April 30, 2020, 03:01:02 PM »
Have resisted commenting on this,   as  believe that operating at this high a voltage is not recommended by MidNite.

There is tolerance on the MCOV:  (MCOV  VRMS @1mA 180V 162-198).

Often when one speaks of 150 VDC,  in these circles,   one might be thinking about PV string voltages,  which,  of course,  vary considerably.   And might be thought of as an uncontrolled voltage source.

Just IMO,  Vic
Off Grid - Two systems -- 4 SW+ 5548s, Surrette 4KS25 1280 AH X2@48V, 11.1 KW STC PV, 3X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  Thanks MN for Great Products/Service/Support!

boB

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Re: MNSPD 115 DC
« Reply #4 on: April 30, 2020, 03:53:17 PM »

Our SPDs (lightning protectors) are normally used to keep the insulation system in the Classic from breaking down.

We hipot each Classic by tying the 4 input and output connections together (PV+, BATT+, PV-, BATT-) and then
applying 2100 volts DC across that combination of 4 connections and chassis ground.
BTW, when we do this, we have to remove a ground-strap inside the Classic that connects ground fault circuitry and capacitors used for connecting battery minus to chassis ground.

Anyway, the SPD just has to conduct during a lightning strike to keep that high voltage from arcing across that insulation barrier.

An SPD115 is probably fine for a Classic 150 but might conduct if you are to make use of its HyperVoc rating of adding 150V to 48V for battery.  The SPD115 may (or may not) conduct in that case.

I would probably try the SPD300 because of this but if you already have SPD115s, then you can give those a try.

Remember that lightning strikes are typically a "common mode" event where BOTH  PV+ and PV- are raised in voltage at the exact same time.  This raised voltage is relative to ground and so that is why the center SPD line goes to GROUND.

The SPD600 would also work because it clamps the voltage below around 1000V but I think an SPD300 would be better because it is more like a mid-voltage clamp well above your Classic 150 PV input voltages but lower than the 800V to 1000V claming of the SPD600




K7IQ

ralova_24

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Re: MNSPD 115 DC
« Reply #5 on: May 15, 2020, 04:54:11 PM »
Thank you boB for your very clear response. I will give MNSPD115 a try to my Classic 150. My PV (Voc) output is around 123Vdc and my country is hot, HyperVoc is not applicable.

BR All,
Rick