the right shunt trip?


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Wolf

Active member
Joined
Sep 25, 2018
Messages
1,760
Hi guys

ABB shunt trip breakers come with 2 types of shut trips.
110V and 24V

When ordering from whomever be sure that they know what they have. I ordered a "24V shunt trip ABB breaker" and put 24V to the trip wires and nothing. Looked at the side and ha 110V promptly requested a return not cheap for the seller but hey know what you are selling as it was advertised as a 24V shunt trip breaker.

If you are shopping for a Shunt trip breaker ABB seems to be the breaker of choice. They can be found relatively cheaply and abundant.

Pictures of the shunt trip Voltage tags. Know what you are getting.

image_tallrg.jpg

image_tktyex.jpg



Wolf
 

Crimp Daddy

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Feb 21, 2018
Messages
974
Yep, regardless of what the breaker is rated for and capable of doing, the shunt trip coil unit has it's own operating voltage. On the plus side, it's an accessory and replaceable. Even if you were stuck with it, you could one to swap it out with.
 

rolfbartels

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Jan 16, 2020
Messages
52
Quick question, the breaker and shunt trip, are you also using the breaker for overload protection, should I be sizing the breaker to the size of my inverter ?, or are we only concerned for the purpose of a shunt trip, my banks will also be protected with HRC fuses.
 

Wolf

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Sep 25, 2018
Messages
1,760
rolfbartels said:
.......................... are you also using the breaker for overload protection, should I be sizing the breaker to the size of my inverter ?,..............................
Absolutely size the breaker to the max Aof your pack.
The shunt trip is there for a panic in whatever BMS you are using.
Overheat, to cold to charge, low V, high V or some other parameter programed in when a threshold is broken to trip the breaker.
Wolf
 

rolfbartels

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Joined
Jan 16, 2020
Messages
52
thanks Wolf,

so i understand a 40A breaker will trip if my inverter load is 80A which is why the MCB needs to at least match the inverter, but for clarity,
should the current tripping function of the MCB be sized to the inverter, so my inverter can do 100A, So do I install a 100A MCB or a 125A MCB, if my inverter short circuits and I start drawing say 150A +, are we expecting the MCB to trip for protection ?.

In my setup, I will eventually have 4 x 7S80P packs, and I will be fusing each pack with a 40A NH000 Fuse, this means theoretically if my inverter decides to draw 150A, the banks are ok with this, but the breaker I would expect to trip right ?,
Lastly if my inverter decides to die, I would be upgrading it to a 5KVa or 5000W 48V unit which is 104A this would mean the same MCB could still be used.
 

Wolf

Active member
Joined
Sep 25, 2018
Messages
1,760
rolfbartels said:
thanks Wolf,

so i understand a 40A breaker will trip if my inverter load is 80A which is why the MCB needs to at least match the inverter, but for clarity,
should the current tripping function of the MCB be sized to the inverter, so my inverter can do 100A, So do I install a 100A MCB or a 125A MCB, if my inverter short circuits and I start drawing say 150A +, are we expecting the MCB to trip for protection ?.

In my setup, I will eventually have 4 x 7S80P packs, and I will be fusing each pack with a 40A NH000 Fuse, this means theoretically if my inverter decides to draw 150A, the banks are ok with this, but the breaker I would expect to trip right ?,
Lastly if my inverter decides to die, I would be upgrading it to a 5KVa or 5000W 48V unit which is 104A this would mean the same MCB could still be used.
OK I think I understand what you are doing.

Each of your packs are going to be protected by a 40A DC NH000 sacrificial fuse (one use)
You will have 4 packs with a potential of 160A.
Your new Inverter will draw max 104A
A regular 125A MCB (no shunt trip) breaker at the inverter would be ok. The only reason for a shunt trip breaker is for a panic not for an overload as the "breaker" part of the breaker is responsible for that.
My only concern is that the NH000 fuses are not smart, as in how do I turn the whole pack off in case of a panic.
Ifall 4 packs are going to a busbar,Iwould then put a 200A shunt trip breaker from the batterybusbar to the distribution busbar.
This is in case you need to isolate all the batteries in a panic. Not necessarily protect from overcurrent.

Wolf
 

rolfbartels

Member
Joined
Jan 16, 2020
Messages
52
Wolf said:
rolfbartels said:
thanks Wolf,

so i understand a 40A breaker will trip if my inverter load is 80A which is why the MCB needs to at least match the inverter, but for clarity,
should the current tripping function of the MCB be sized to the inverter, so my inverter can do 100A, So do I install a 100A MCB or a 125A MCB, if my inverter short circuits and I start drawing say 150A +, are we expecting the MCB to trip for protection ?.

In my setup, I will eventually have 4 x 7S80P packs, and I will be fusing each pack with a 40A NH000 Fuse, this means theoretically if my inverter decides to draw 150A, the banks are ok with this, but the breaker I would expect to trip right ?,
Lastly if my inverter decides to die, I would be upgrading it to a 5KVa or 5000W 48V unit which is 104A this would mean the same MCB could still be used.
OK I think I understand what you are doing.

Each of your packs are going to be protected by a 40A DC NH000 sacrificial fuse (one use)
You will have 4 packs with a potential of 160A.
Your new Inverter will draw max 104A
A regular 125A MCB (no shunt trip) breaker at the inverter would be ok. The only reason for a shunt trip breaker is for a panic not for an overload as the "breaker" part of the breaker is responsible for that.
My only concern is that the NH000 fuses are not smart, as in how do I turn the whole pack off in case of a panic.
Ifall 4 packs are going to a busbar,Iwould then put a 200A shunt trip breaker from the batterybusbar to the distribution busbar.
This is in case you need to isolate all the batteries in a panic. Not necessarily protect from overcurrent.

Wolf

Yeah so the breaker will have a shunt trip attached for panic, like cell over or under voltage or temperature issue ect and this will isolate all the battery banks from the inverter. TheNH-00fuses are 1 use only and are there in the even the bank does something stupid and short out and instead of pulling massive currentfrom the other 3 banks and potentially causing a fire or something, this would blow isolating the faulty bank from the rest, these fuses are houses in a battery disconnect switch which then also allow me the option of isolating a bank for maintenance. I am doing 18650 cell level fusing with 35AWG tinned wire, so I have multiple points of protection.

I have opted for the NH-00 blade fuses only because the interrupt capacity is 120ka where as a 40a dc breaker is only around 10ka. these fuses are like $3 so not a huge expense and it's not like I'll be burning through them.

I did get an answer for my original question in another thread about using just a standard isolator or a isolator with 125A current overload protection, overload protection it is
I unfortunately live in South Africa and those ABB MCCB's breaker are not available here which is why I have to use a MCB instead.
 
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