Gareth J
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RF Solutions MAINSLINK Remote Control System,869.5MHz | RS
uk.rs-online.com
This would be perfect. With longer range.
RF Solutions MAINSLINK Remote Control System,869.5MHz | RS
uk.rs-online.com
This would be perfect. With longer range.
Sounds like you want make explode somethingAnyone know anything about sending a signal down a wire a fair distance? In the region of 500m but say 1km for safety.
I basically want to operate a relay at one end from a signal at the other. All a bit hypothetical at this point but if anyone has any experience with such things be great to hear.
My knowledge is near zero. Likely I'd need to transform the signal to something that likes going a long way through cables and get a cable that keeps the signal intact. Can it be done analogue? Reliably?
I did a similar job year's ago, switching a bore pump from a float switch in a tank , it was around 800 meters I just used 1.5mm swa in the trench with the pipe.
Nah, needs to be a bit more repeatable than that!Sounds like you want make explode something
Yes, we've done similar with, albeit not quite so far, pumps in holes with swa. Trying to keep costs down as it's probably only a marginal improvement though and, as the pipework exists already, just not the communication, seems to make sense to me to see if there's a less expensive route. Moleing in SWA or just a whole new bit of pipe (and use the water pressure as the communication medium) would be the right thing to do but not worth it.I did a similar job year's ago, switching a bore pump from a float switch in a tank , it was around 800 meters I just used 1.5mm swa in the trench with the pipe.
If the pipework is there cannot you use a pressure switch?Nah, needs to be a bit more repeatable than that!
Yes, we've done similar with, albeit not quite so far, pumps in holes with swa. Trying to keep costs down as it's probably only a marginal improvement though and, as the pipework exists already, just not the communication, seems to make sense to me to see if there's a less expensive route. Moleing in SWA or just a whole new bit of pipe (and use the water pressure as the communication medium) would be the right thing to do but not worth it.
Not necessarily true.Leave it as AC as AC transmits further and the higher the voltage the further it will go
Is it?Not necessarily true.
Note I'm not saying it's not the better solution in this context but the blanket statement AC transmits further is not true. There's a reason why DC is used for high voltage long distance power transmission.
It is in certain scenarios where they have a free reign.Is it?
It is in certain scenarios where they have a free reign.
AC is easy to change voltage due to transformers, equally its easier to switch off because of the zero crossings.
DC however doesn't suffer skin effects because of its very nature so you simply eliminate those losses that are associated with AC. For a given cable there is a maximum voltage and maximum current that can be conducted. In order to maximise power transmission you need to maximise both and for a fixed voltage the maximum current you can transfer is the RMS (root mean square) current. For DC this is simply the current, for AC it is 1/sqrt(3) (for 3 phase, might have got that wrong - too early in the morning but the point is it's less). That's due mainly because of the heating losses in the wire.
Net result is you can for a given cable transmit more power more efficiently using DC when you're talking losses. Conversely you use less cable as well for the same power transmission. The flip side is that converting DC voltages is more difficult and therefore more costly so its a balancing / weighing act of what's more important - the energy saving due to more efficient power transfer vs. the added cost of the electronics to interface to other equipment.
It makes more sense if you're doing long distance high power links between power stations for example, or especially if you have to change frequency.
@sako243 , Ed what was that fibre optic option you came up. That cable is cheap and available in any length, that's switching gate automation at over a mile away. They ripped out all the radio/sim signal stuff because it was too hit and miss. Works very well now on fibre.
Bob
We did some stuff with fibre optic at school.
This was basically a closed box with a bulb in and the fibre optic cable pushed through a gland into the box.
The other end of the cable went into a box with a light sensor fitted.
They were only runs of a meter or so but showed the practical side of switching something on/off.
No idea what sort of distance that would work over but if a roll of the cable was cheap enough you could bench test it easily.
Not sure if an installation of fibre optic will be any easier than copper though?
You can't bang the stuff onto fence posts with staples...
You can get it in SWA in any length you want, cant remember the name of the company but one supplier will put the ends on for you.
SWA Loose Tube Fibre Cable
Steel Wire Armoured Loose Tube Fibre Cable, Available from 4 - 24 Corewww.fibrefox.co.uk
Yes not disagreeing with the theory rather the fact that probably over 95% of hv dist is ac.It is in certain scenarios where they have a free reign.
AC is easy to change voltage due to transformers, equally its easier to switch off because of the zero crossings.
DC however doesn't suffer skin effects because of its very nature so you simply eliminate those losses that are associated with AC. For a given cable there is a maximum voltage and maximum current that can be conducted. In order to maximise power transmission you need to maximise both and for a fixed voltage the maximum current you can transfer is the RMS (root mean square) current. For DC this is simply the current, for AC it is 1/sqrt(3) (for 3 phase, might have got that wrong - too early in the morning but the point is it's less). That's due mainly because of the heating losses in the wire.
Net result is you can for a given cable transmit more power more efficiently using DC when you're talking losses. Conversely you use less cable as well for the same power transmission. The flip side is that converting DC voltages is more difficult and therefore more costly so its a balancing / weighing act of what's more important - the energy saving due to more efficient power transfer vs. the added cost of the electronics to interface to other equipment.
It makes more sense if you're doing long distance high power links between power stations for example, or especially if you have to change frequency.