Low voltage to 230v over 100 meters?!

Forums › Gadgets, robotics, home automation, electronics (including wearables) › Low voltage to 230v over 100 meters?!

stuffed

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#196466 1-Jun-2016 11:24

Ok you sparkies - can/how this be done?! (for CCTV).
Need 230volt at 10 amps but only draw about .3 of an amp.
About 100 meters from a 230v supply.
Currently 2 unused Cat 5 cables in the duct to where we need this 230v supply.
Can we send low voltage that distance and convert to 230v?!
Thanks from a non sparkie.

Why work on Wednesday and stuff up 2 good long weekends

Mattmannz

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#1563579 1-Jun-2016 11:44

Ethernet cable isn't designed for 200+v. Can you use one of the leads as a draw wire to pull through some flex?

gregmcc

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#1563600 1-Jun-2016 12:23

Smallest size cable over that distance will be 10mm2 (buried in duct).

that will give you a standard 10A 230V circuit

You could put in a permanent connection and a 6 A circuit breaker, that will get you down to a 4mm2 cable

richms

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#1563601 1-Jun-2016 12:28

What CCTV needs 230v? Everything I have seen is all extra low voltage so a simple power over ethernet converter would have dealt with it.

70 watts is within the realm of PoE, assuming the 0.3A is actual and not just the rating on a powersupply that is actually going to be much less.

Richard rich.ms

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#1563610 1-Jun-2016 12:41

You might get away with something like this if you go to an intermediate voltage. For example, you could convert down to 24 or 48 volts. This might be doable using existing maritime components. 24 volts is fairly standard, not sure about 48 volts but you could get that with two 24-volt transformers in series. At 24 volts the cables would need to carry roughly 3 amps. I don't know how much loss you would encounter over 100 metres.

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chimera

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#1563612 1-Jun-2016 12:44

richms:

What CCTV needs 230v? Everything I have seen is all extra low voltage so a simple power over ethernet converter would have dealt with it.

70 watts is within the realm of PoE, assuming the 0.3A is actual and not just the rating on a powersupply that is actually going to be much less.

Exactly what I was thinking!

He did mention 100m though, so pretty much on the limits of an Ethernet run without being repeated, let alone running PoE over it.

richms

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#1563614 1-Jun-2016 12:58

chimera:

Exactly what I was thinking!

He did mention 100m though, so pretty much on the limits of an Ethernet run without being repeated, let alone running PoE over it.

POE is specced to work out to 100m. 2 runs so worst case put a POE to 12v or whatever the device really takes adapter on both runs and parallel them up.

Although in saying that I have only seen 50-60w POE used to power devices with their own internal converters, not seen a seperate standalone 12v output adapter for the higher power POE standards.

Since the 802.3at standard only allows you to use 2 pairs, you could always get 4 converters and break the pairs out if it came to it.

Richard rich.ms

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stuffed

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#1563754 1-Jun-2016 16:23

Thanks everyone for your input and will pass it on.
I too was surprised at the 230v requirement but it may be for the connection into the fibre.
Just that we have quite a number of retailers that supply a power source for the CCTV in our small CBD and one has gone sour! It is costing them about $2 per month.

Why work on Wednesday and stuff up 2 good long weekends

richms

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#1563758 1-Jun-2016 16:35

If you can identify the gear on the end then perhaps some other suggestions can be made?

Richard rich.ms

Aredwood

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#1563908 1-Jun-2016 22:58

Since you said that the 2 cat5 cables are unused, this makes it easy. Just strip back both cables. Twist all of the conductors in each cable together. So you would then be using each cat5 as if it was only a single strand cable. Assuming each strand is 26AWG, you will have just over 1mm2 in total cable size. If you then run 48VDC over it, 1.5A will then give you 70W. And you will have about 5.5V of volt drop. I haven't allowed for possible temp rise of the cable increasing the volt drop though.

Also the definition of "extra low voltage" is less than 120V ripple free DC. Or 50V AC. Of course it doesn't say if that is in reference to ground, or max line to line voltage. So you might be able to connect one of the conductors to +120VDC. And the other to -120VDC. So you will have a total of 240VDC at the far end. And if you have switchmode stepdown adaptors at the far end, that can handle anything between 100-240VAC. Virtually all of them simple rectify the mains to DC anyway. Before stepping it down. So you would be able to wire the +-120VDC into the existing power supplies. Main difficulty would be finding an off the shelf power supply that outputs +-120VDC.

But the easiest way is to simply to offer to pay that retailer $3 per month for the power used. Im guessing that you are a landlord or working on behalf of the landlord. So you / they would be able to account for that $3/month at the next rent review.

Any idea if that retailer tries to bill their ISP for the power used by the default supplied modem/router? Or bill their cellphone network for the power used to charge their cellphone? Chorus has a term in their standard UFB contract that they are not responsible for paying for the power used by their fibre ONT. Kind of scary that they had to include that clause.

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#1563917 1-Jun-2016 23:39

Any idea if that retailer tries to bill their ISP for the power used by the default supplied modem/router? Or bill their cellphone network for the power used to charge their cellphone? Chorus has a term in their standard UFB contract that they are not responsible for paying for the power used by their fibre ONT. Kind of scary that they had to include that clause.

That's because the ONT is actually part of the Chorus Network, not the customer's.

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stuffed

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#1564131 2-Jun-2016 11:49

Will toss these ideas to the contractor.
Appreciate the detail you have given.
Thanks

Why work on Wednesday and stuff up 2 good long weekends