A Forum run by Enthusiasts of MidNite Solar

General Category => System Design and Layout => Topic started by: Beyla on April 07, 2019, 11:32:52 AM

Title: Spare fuses for the MNPV6HV 4X
Post by: Beyla on April 07, 2019, 11:32:52 AM
The documentation states that I have 6 x 600v 15Amp fuses in the fuse holders. Which replacement fuses should I get? Apparently this fuse does not exist anymore at 600volts, there is the 1000V 15 amp fuse MNFUSE1000-15. The most a 600V fuse will provide is 7 amps from what I can see. I plan on running 2X 260watt panels per string. Many thanks for any response. Apparently my provided fuses are discontinued?
Title: Re: Spare fuses for the MNPV6HV 4X
Post by: ClassicCrazy on April 07, 2019, 02:49:57 PM
I don't think that using a 1000v rated fuse instead of 600v rated fuse should  be any issue as long as they are the same physical size to fit the fuse holder.

Larry
Title: Re: Spare fuses for the MNPV6HV 4X
Post by: Beyla on April 07, 2019, 06:35:31 PM
Hehe, a little bit worried about the ”should” part of the answer, lol thanks anyway.

Can anyone point me to the official replacement fuse for the aforementioned Disco-Combiner?
Thanks again.
Title: Re: Spare fuses for the MNPV6HV 4X
Post by: ClassicCrazy on April 07, 2019, 07:25:51 PM
" The proper application of an over current protective device according to its voltage rating requires that the voltage rating of the device be equal to or greater than the system voltage.  It can be higher but never lower.  "

http://www.cooperindustries.com/content/dam/public/bussmann/Electrical/Resources/solution-center/technical_library/BUS_Ele_Tech_Lib_Voltage_Rating.pdf

Take a look at above link

I am sure any solar supplier like Northern Arizona Wind Sun can get you the correct fuses - or send  question to support at Midnite.

Larry
Title: Re: Spare fuses for the MNPV6HV 4X
Post by: Beyla on April 08, 2019, 08:23:51 AM
Thank you ClassicCrazy, much appreciated. I understand that it’s the amperage that counts but I was worried that a fuse meant to run at 1000 volts and break at 15 amps might not break at 15 amps under 600 volts, no disrespect intended in my initial response, I am just a perfectionist (my bad) and this bad habit drives me nuts at times, I can imagine what it does to most people and I apologize if it came out sounding dismissive, it was not my intent. I appreciate your input and I’m sure you are competent in the matter, much appreciated and thanks again.
Regards,
Title: Re: Spare fuses for the MNPV6HV 4X
Post by: tecnodave on April 08, 2019, 09:09:47 AM
Belya,

With a Classic 150 you should not be using a grid tie combiner with fuses. The correct combiner would be the MNPV6 equipped with MNEPV Breakers......in grid tie applications only 600 volts is allowed in U.S.A. But in Europe 1000 volt is the standard.  So MidNite has their boxes rated for the euro standard as well as the NEC standard used here. The combiners are equipped for fuses or breakers. Breakers are almost allways used for off grid as the voltages are not high enough for the need of high voltages. You cannot turn off a fuse, you must power down the system to remove the fuse! This makes trouble shooting very difficult as you cannot turn off one string of panels for trouble shooting.
David
Title: Re: Spare fuses for the MNPV6HV 4X
Post by: FNG on April 08, 2019, 12:19:39 PM
As stated, the 1000v fuses are a direct replacement for the 600v fuse, They are the same cost so it made no sense for us to stock and sell 600v and 1000v fuses.
Title: Re: Spare fuses for the MNPV6HV 4X
Post by: Beyla on April 09, 2019, 04:37:08 PM
Thanks David,

This is an off-grid installation that will only draw power from the utility when absolutely required to charge the batteries. I already have an AC sub-panel in my shed (big shed). I want to run my backyard pond and lights as well as my gazebo power from solar energy. Also in case of emergencies. The system will never output energy to the grid but simply to the backyard and “shed”  as separate identified electrical outlets. I already have an MNPV6 and I can’t use it because it does not have a RSS interface in it and I require a RSS system. RSS is required because the “shed” is basically a building in my backyard and the firefighters want to push a button instead of pulling on some breakers in the MNPV6, even if it was on the exterior wall accessible and reachable. They want a Battery Disconnnect as well.

I suppose I could put the MNPV6 on the roof, remove the connecting bar and run my wires down the pipe to the DicoCombiner with all wires and that would prevent my fuses from blowing. I have 6 MN 15@mp breakers inside it. Does that make sense ?

I know it’s kinda wasteful, but I already have those parts. I live in Canada, we have the Electrical Solar Safety Authority inspection required and city permit for solar system exceeding 5m square feet , which is 3 feet by 15 feet of solar panel roughly. I have more than this area, therefore unfortunately fall in that category.
Title: Re: Spare fuses for the MNPV6HV 4X
Post by: Westbranch on April 09, 2019, 06:31:54 PM
I would ask the simple question of,..... "Please tell me which BRAND's of RSS  I can use that will be certified"...
Title: Re: Spare fuses for the MNPV6HV 4X
Post by: tecnodave on April 10, 2019, 11:50:29 AM
Beyla,
Here in the US , building inspectors require shutdown on a "dwelling" meant to be occupied the shutdown is required, I have never heard of that requirement in a "non-occupied structure" as a shed is properly termed. You have some over zealous inspectors misreading the NEC.
How to deal with over zealous building authorities is difficult at best. I have my solar systems on non buildings so I do not have to answer to them. My power house is a R.V. "workshop"  that has been gutted due to extreme rotting, it's leak free mostly and contains electronics, batteries are in a small container next to RV and a 40 foot shipping container serves as the platform for the array's. The container is not considered a building here so no codes apply, my array goes side to side , end to end. The building inspectors were not too happy with that but the motorhome came with a "power plant" and built in California  so is state certified as a power producing unit for that purpose. I invited the fire chief to inspect the installation and provided some education for his firefighters as to off grid systems that they do not get in their normal training. Chief was happy with that and he squelched the building requirements. He did state that the only reason that roof setback was required was so that firefighters could access the roof. They typically do not access the roof of non dwellings and have no reason to ventilate those structures. I do not have a shutdown system as specified in the code but do have shutoff boxes on the array outputs and an AC shutdown at the RV and at the dwelling. These are common two pole fused switch boxes used for AC but are painted bright red with clear labeling as what to do in case of fire. The fuses have been replaced with copper tubing so they are only "switches" and are rated AC-DC (Square D boxes). I am not sure about the codes there and how they are interperated, but I think that they are overstepping. 

If you decide to use the shutdown and the MNPV-6 combiner , I would suggest using the MNEPV breakers to limit the current for each string and use only one fuse in the shutdown rated to switch off the total output of the array rated for the total current of the array. 
Title: Re: Spare fuses for the MNPV6HV 4X
Post by: Beyla on April 20, 2019, 03:43:26 PM
Thank you very much Dave. I’ll be using 5 strings of 2 panels @ 15 amps per string. If I use one fuse only to shutdown the Disco-Combiner that fuse should be rated at 75 amps, is this correct?

Currently I have 15 amps fuses in my Dusco-Combiner.

Regards,