Author Topic: How do you test a DC shunt?  (Read 295 times)

Vic

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Re: How do you test a DC shunt?
« Reply #15 on: October 17, 2020, 10:24:25 PM »
Ok,  Thanks,  just was curious.

The old Xantrex SW+ 5548s here weigh about the same  --  143-145Lbs in the box,   and about 138 Lbs,  or so without  the packing.   Could not come close to hefting them onto the wall,  without help,   and that was 15 years ago,   at that.

Shipping is a killer these days.

Good luck,    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: How do you test a DC shunt?
« Reply #16 on: October 17, 2020, 10:25:23 PM »
Here's a bit of FYI

I an old analog guy, and I like to watch analog meters more than a digital display.
So i connected a analog meter to the same sense wires on the Whizbang jr so I could see the current flow on a analog meter. Apparently the load from the meter caused issues with the Whizbang, so I ended up placing a 100 A 75 mV shunt in the high side of the battery lead to the inverter.

Once the meter was removed from the Whizbang's shunt, everyone was happy.
I did add a 200mA fuse in the shunt's sense wires that fed the analog meter, since I was measuring current in the high side.

There was an old dead guy named Kirchoff that said current in and current out of a node had to be the same, so a shunt in the high side will read the same as one in the negative lead like the Whizbang.
It's possible the other equipment doesn't like the shunt the Whizbang is married to. I'd add another shunt to the battery neg lead just for the external equipment and see what happens.

Mike, wb8vge


That is surprising that some analog meter would make a difference at all.  The resistance of a 500A 50mV shunt is 100 micro-Ohms.  I doubt that your meter would be loading anything down unless you put it into current mode.  THAT would be low resistance.   It would have to apply some amount of load  OR maybe some voltage to affect the shunt reading I would think.

What kind of meter was it ?  Was it internal battery powered ?   If externally powered, I might understand some kind of connection from one of the meter probe leads to GND or something that might affect operation.


K7IQ

qrper

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Re: How do you test a DC shunt?
« Reply #17 on: October 18, 2020, 10:44:17 AM »
Here's a bit of FYI

I an old analog guy, and I like to watch analog meters more than a digital display.
So i connected a analog meter to the same sense wires on the Whizbang jr so I could see the current flow on a analog meter. Apparently the load from the meter caused issues with the Whizbang, so I ended up placing a 100 A 75 mV shunt in the high side of the battery lead to the inverter.

Once the meter was removed from the Whizbang's shunt, everyone was happy.
I did add a 200mA fuse in the shunt's sense wires that fed the analog meter, since I was measuring current in the high side.

There was an old dead guy named Kirchoff that said current in and current out of a node had to be the same, so a shunt in the high side will read the same as one in the negative lead like the Whizbang.
It's possible the other equipment doesn't like the shunt the Whizbang is married to. I'd add another shunt to the battery neg lead just for the external equipment and see what happens.

Mike, wb8vge


That is surprising that some analog meter would make a difference at all.  The resistance of a 500A 50mV shunt is 100 micro-Ohms.  I doubt that your meter would be loading anything down unless you put it into current mode.  THAT would be low resistance.   It would have to apply some amount of load  OR maybe some voltage to affect the shunt reading I would think.

What kind of meter was it ?  Was it internal battery powered ?   If externally powered, I might understand some kind of connection from one of the meter probe leads to GND or something that might affect operation.

BoB

It was (is) a 75mV analog meter. That meter required no power to operate.
I too thought it shouldn't have caused any issues, but when I opened another one, I found a resistor between the meter's coil terminal. I don't remember what the value was, and I'm guessing here, the meter may have been 200uA and the resistor was used to scale the movement to the required 75mV input. Of course, there was no documentation supplied with this Chinese meter.

Another issue was the scaling. The 500A shunt with the Whizbang and a 100A meter didn't provide much data. Even at 100A, the Chinese meter would barely move a quarter inch off scale.

The fix was to insert another 100A 75mV shunt in the high side of the inverter cable. Looking back, I don't know why I didn't put the shunt in the negative input to the inverter (the whizbang was in the negative lead) right at the battery.

The photo attached shows the 72mm DIN meters. The bottom right one is not doing anything. The bottom left is the one with the additional shunt added.

mike
System one: 7kWp w/ Trina 250 W panels @90 Vdc. Classic 150 to 16-6 V U.S batteries. Trace 5548 sine wave inverter.
System two: 6kWp grid tie with solaredge inverter.
System three: Midnite Brat, two 120 W Astropower modules, 100 Ah battery. Runs the LED streetlight in the back yard.

qrper

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Re: How do you test a DC shunt?
« Reply #18 on: October 18, 2020, 10:54:38 AM »
Ok,  Thanks,  just was curious.

The old Xantrex SW+ 5548s here weigh about the same  --  143-145Lbs in the box,   and about 138 Lbs,  or so without  the packing.   Could not come close to hefting them onto the wall,  without help,   and that was 15 years ago,   at that.

Shipping is a killer these days.

Good luck,    Vic

Vic,

You got that one right!

Once, way, way back, I had to send my 5548 back to trace. It wouldn't turn on. They replaced a fuse, charged me an amazing amount of money to replace said fuse, and then I had to pay shipping back to Ohio. I can't imagine shipping that bad boy again, let alone getting it off the wall.
That being said, and I don't want to take over this thread, but do you know of anyone that repairs these old Trace inverters? The one I have has been on 24/7 since January 2020. It's 18 years old. I'd like to get a backup on line, and I think i'll see Jesus before the Midnite Solar inverters get on the market.

mike

The
System one: 7kWp w/ Trina 250 W panels @90 Vdc. Classic 150 to 16-6 V U.S batteries. Trace 5548 sine wave inverter.
System two: 6kWp grid tie with solaredge inverter.
System three: Midnite Brat, two 120 W Astropower modules, 100 Ah battery. Runs the LED streetlight in the back yard.

ClassicCrazy

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Re: How do you test a DC shunt?
« Reply #19 on: October 18, 2020, 12:58:39 PM »
Ok,  Thanks,  just was curious.

The old Xantrex SW+ 5548s here weigh about the same  --  143-145Lbs in the box,   and about 138 Lbs,  or so without  the packing.   Could not come close to hefting them onto the wall,  without help,   and that was 15 years ago,   at that.

Shipping is a killer these days.

Good luck,    Vic

Jim Kerbel used to repair Trace stuff . You might check with him.
http://www.pv-systems.org/page/about-us

Larry

Vic,

You got that one right!

Once, way, way back, I had to send my 5548 back to trace. It wouldn't turn on. They replaced a fuse, charged me an amazing amount of money to replace said fuse, and then I had to pay shipping back to Ohio. I can't imagine shipping that bad boy again, let alone getting it off the wall.
That being said, and I don't want to take over this thread, but do you know of anyone that repairs these old Trace inverters? The one I have has been on 24/7 since January 2020. It's 18 years old. I'd like to get a backup on line, and I think i'll see Jesus before the Midnite Solar inverters get on the market.

mike

The
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

Trukinbear

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Re: How do you test a DC shunt?
« Reply #20 on: October 18, 2020, 01:07:17 PM »
Yeah, way heavier than the Heart, and the Trace units it replaced. Since this heavy sucker went on the backplate before the E-panel I'm not sure it will even come off without uninstalling the E-panel. Does anyone have experience like that with the MNSMA-short backplate, and MNSMA-OG E-panel - will I have to take it all down to replace my inverter?
SMA Solar Sunny Island SI6048
JA Solar 330W 72 cell panels (18)
Classic 250 (2)
MODBUS/Canbus comm adaptor for Sunny Island
SMA-OG E-panel
WhizBang Jr
MNSPD300V (3)
Atkinson GSCM mini-i
Onan Quiet Diesel QD-8000
Monterey 986Ah 'Big Sur' 24-125-11 48V battery
Off the grid on the PNW coast

Trukinbear

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Re: How do you test a DC shunt?
« Reply #21 on: October 20, 2020, 06:07:23 PM »
SMA support says the Sunny Island should not be hooked to the DC shunt when the MODBUS/Canbus communications adaptor is used. While not in the documentation from MidNite that came with this adaptor, nor mentioned anywhere in SMA's difficult to read manual to get this to work right during initial setup I should have:
a) #225.01 BatCurSnsTyp - set to NONE
b) #250.28 ChrgCtlOp - set to SMA
SMA Solar Sunny Island SI6048
JA Solar 330W 72 cell panels (18)
Classic 250 (2)
MODBUS/Canbus comm adaptor for Sunny Island
SMA-OG E-panel
WhizBang Jr
MNSPD300V (3)
Atkinson GSCM mini-i
Onan Quiet Diesel QD-8000
Monterey 986Ah 'Big Sur' 24-125-11 48V battery
Off the grid on the PNW coast

ClassicCrazy

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Re: How do you test a DC shunt?
« Reply #22 on: October 20, 2020, 07:06:51 PM »
SMA support says the Sunny Island should not be hooked to the DC shunt when the MODBUS/Canbus communications adaptor is used. While not in the documentation from MidNite that came with this adaptor, nor mentioned anywhere in SMA's difficult to read manual to get this to work right during initial setup I should have:
a) #225.01 BatCurSnsTyp - set to NONE
b) #250.28 ChrgCtlOp - set to SMA

Good to hear that you dug into it with SMA and got to the root of the problem.

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

Trukinbear

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Re: How do you test a DC shunt?
« Reply #23 on: October 21, 2020, 01:41:55 PM »
They are also replacing the SI6048 under warranty due to the damage from operating it like this for 14 months. I'm very lucky, though I'm not sure how lucky I'll feel trying to swap these out after it gets here.
SMA Solar Sunny Island SI6048
JA Solar 330W 72 cell panels (18)
Classic 250 (2)
MODBUS/Canbus comm adaptor for Sunny Island
SMA-OG E-panel
WhizBang Jr
MNSPD300V (3)
Atkinson GSCM mini-i
Onan Quiet Diesel QD-8000
Monterey 986Ah 'Big Sur' 24-125-11 48V battery
Off the grid on the PNW coast

boB

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Re: How do you test a DC shunt?
« Reply #24 on: October 21, 2020, 04:54:10 PM »
SMA support says the Sunny Island should not be hooked to the DC shunt when the MODBUS/Canbus communications adaptor is used. While not in the documentation from MidNite that came with this adaptor, nor mentioned anywhere in SMA's difficult to read manual to get this to work right during initial setup I should have:
a) #225.01 BatCurSnsTyp - set to NONE
b) #250.28 ChrgCtlOp - set to SMA

Doesn't make sense to me that the SI would be running without a shunt, since it is in "charge" of the whole system and tells the Classics what to do.

The Classics would need to be on the SI side of the shunt (not the battery negative) but I do not understand why SMA would say no shunt.

There are all sorts of adjustments in the SMA menus as far as I remember.
K7IQ

Trukinbear

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Re: How do you test a DC shunt?
« Reply #25 on: October 21, 2020, 05:56:44 PM »
The shunt is still physically there with the WhizBang Jr attached, and all power still flows through the shunt as it always has - BUT the sensor wires from the Sunny Island to the shunt are eliminated, and the Sunny Island is told there is no shunt (or it would shut off actually) and that it has SMA chargers connected instead of selecting DC coupled (even if it IS DC coupled) it needs to think the two Classic 250's are the non UL certified SMA DC-coupled chargers they don't sell in the States. It has acted screwy for 14 months, it seems to be behaving correctly now, just before they replace it. Any idea if the SI can be R&R with the E-panel in situ?
SMA Solar Sunny Island SI6048
JA Solar 330W 72 cell panels (18)
Classic 250 (2)
MODBUS/Canbus comm adaptor for Sunny Island
SMA-OG E-panel
WhizBang Jr
MNSPD300V (3)
Atkinson GSCM mini-i
Onan Quiet Diesel QD-8000
Monterey 986Ah 'Big Sur' 24-125-11 48V battery
Off the grid on the PNW coast

Trukinbear

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Re: How do you test a DC shunt?
« Reply #26 on: October 21, 2020, 06:01:32 PM »
Funny thing, in the SMA manual it warned me that severe battery damage would occur if I failed to install, and properly calibrate the DC shunt, so I did... and shouldn't have it seems now. Nowhere does it mention any of this. I'm curious to know if you just haven't put very many of these in the field, or if everyone else found out this same thing from SMA support and didn't bother to tell anyone. Anyway, I hope this info is useful to someone other than just me.
SMA Solar Sunny Island SI6048
JA Solar 330W 72 cell panels (18)
Classic 250 (2)
MODBUS/Canbus comm adaptor for Sunny Island
SMA-OG E-panel
WhizBang Jr
MNSPD300V (3)
Atkinson GSCM mini-i
Onan Quiet Diesel QD-8000
Monterey 986Ah 'Big Sur' 24-125-11 48V battery
Off the grid on the PNW coast

boB

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Re: How do you test a DC shunt?
« Reply #27 on: October 21, 2020, 06:26:36 PM »

We have shipped several of these systems now.   I am not familiar with anyone else being told to disconnect the shunts from the SI probably because I'm not in the support department.   I mentioned this (your situation) to the others and nobody has claimed this to be the case, yet.

I wish I could hear more about it and hopefully will.

Also not sure about the R&R part.   Yet.

K7IQ

Trukinbear

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Re: How do you test a DC shunt?
« Reply #28 on: October 21, 2020, 06:55:12 PM »
It could be one of those 'common knowledge' things where they were purchased by people who already knew what they were doing, or it could be that none of these systems are operating properly, and rather than appearing to just fail they just act erratically which people probably attribute to those German engineers at SMA. Their manual reads like the key-book for the Enigma machine. Yes, there are a ton of options, they just don't tell you much more than a cryptic abbreviation often with no verbiage about what the selections actually do, or more importantly why/what you need to change them for/to. Explanations of warning messages and failure codes are even worse. I did end up going to the SI6.0 manual for some slightly better-explained codes... I just have to trust they are the same codes carried over from the SI6048.
SMA Solar Sunny Island SI6048
JA Solar 330W 72 cell panels (18)
Classic 250 (2)
MODBUS/Canbus comm adaptor for Sunny Island
SMA-OG E-panel
WhizBang Jr
MNSPD300V (3)
Atkinson GSCM mini-i
Onan Quiet Diesel QD-8000
Monterey 986Ah 'Big Sur' 24-125-11 48V battery
Off the grid on the PNW coast

boB

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Re: How do you test a DC shunt?
« Reply #29 on: October 21, 2020, 07:53:45 PM »

So, did the E-Panel with SMA SI and Classics come with with the shunts wired to the Sunny Island inverter ?

K7IQ