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230V AC to 12V DC Step Down Converter
#11
(03-03-2020, 09:35 AM)clementhk Wrote: https://uk.rs-online.com/web/p/contactors/8175020/
What does that 3 pole mean?

3 pole means 3 phase. If you look at the front, it shows L1, L2, L3. L = Line.

You can use a 3 pole contactor and not use it for 3 phase. Let's say you have 1 input and 3 output, for example. but you want power to disconnected all at once if any of the one legs has an issue. This would be similar to a mains breaker that pops disconnect a whole panel if a major enough event occurs.
Problem is, you wouldn't be able to individually disconnect lines unless they went through a second contactor/breaker (which could be done w/o issues as well)
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#12
3 pole doesnt necesary have to be 3 phases but actually 3 different isolated contacts.

For instance you buy 2 pole to accomondate full isolation of battery and you get 4 pole for full isolation of 3phase systems Wink
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#13
(03-03-2020, 11:09 AM)Redpacket Wrote: I'm thinking it might make sense to split up your loads eg
- get the low amps items onto one smaller converter & use a low voltage cutout to switch that on/off
- for the high load gear, if you really want to switch it, you need to be looking for an EV (electric vehicle) type contactor with precharge. Note regular automotive & marine ones are usually only rated for max 32VDC, you've got approx 50+ volts from a full "48V" pack. If you're lucky, some gear goes up to 60V.
- low voltage on/off control of the large inverter would be a much better way to do it (if you can find a way to control your inverter this way)
- also note connecting a big inverters input to batteries is an exciting time because of inrush currents, you'll get a massive "splat" spark as you connect,
- also think about a delay so after low volts tripped, it won't reconnect for a bit or you will get a nasty on/off/on/off... oscillation happening.

Thanks, I'll look into splitting up my load.

(03-03-2020, 01:04 PM)Korishan Wrote:
(03-03-2020, 09:35 AM)clementhk Wrote: https://uk.rs-online.com/web/p/contactors/8175020/
What does that 3 pole mean?

3 pole means 3 phase. If you look at the front, it shows L1, L2, L3.  L = Line.

You can use a 3 pole contactor and not use it for 3 phase. Let's say you have 1 input and 3 output, for example. but you want power to disconnected all at once if any of the one legs has an issue. This would be similar to a mains breaker that pops disconnect a whole panel if a major enough event occurs.
Problem is, you wouldn't be able to individually disconnect lines unless they went through a second contactor/breaker (which could be done w/o issues as well)

Thanks, if I only use one of the 3 pole, can the load still go up to 80A on this contactor?
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#14
300VDC @ 80A is the max each of the contacts can handle. so yeah, each contact can do 80A. Also, you can drop voltage and increase amp rating. So halving the voltage to 150VDC won't double the amps to 160A. You are still limited to 80A.
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#15
Use these in parallel :
https://secondlifestorage.com/showthread.php?tid=8065

The idle losses are about 7W each and you can stack up as many as you want in parallel for higher amps because they are fully isolated.

Don't solder to them and try to get the crimp terminal plugs to fit.

The units can be switched on and off with a few mA between two pins... however the supply for each board would need a separate fuse.

Also with a 3 pole breaker you can just use all 3 contacts in parallel, so if you have an 80A breaker, wire all 3 in paralle and you get 240A. BUT...... beware that the contacts need to be good as you can end up with one pole thermally tripping the device early. For example if you end up with 60A, 60A, 90A flowing. the third pole at 90A will try to trip the device.

I have used some cheap 4 pole DC breakers in paralle with copper busbars (consumer / fuse unit bars) to cross connect the poles. Using lower amp rated poles in parallel eases contact isseus, like using a 4 pole 20A breaker in paralell for a 80A supply.
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