What does 9-30V DC supply mean?

I need to install a sensor which requires a "9-30V DC +/-10%" supply. Clearly i need to buy a transformer to step down the mains voltage, but does 9-30V mean the transformer could be, say, 12V or 24V, i.e. anything between 9 and 30V? Or does 9-30V mean something else? FYI, the sensor only has one wire for power - see attached pic.

Yep, anything from 9V to 30V, give or take 10%.

Lurch said:

Yep, anything from 9V to 30V, give or take 10%.

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OK, any advantage to getting a higher-voltage transformer, e.g. 24V, over a basic 12V one? 

Also, how do i tackle the single-cable issue? I have a 12V DC transformer (for LED lights), but that has two (black and red) wires.

europa said:

OK, any advantage to getting a higher-voltage transformer, e.g. 24V, over a basic 12V one? 

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Probably current differential but tbh for the difference it won't make any odds at this end of the scale.

europa said:

Also, how do i tackle the single-cable issue? I have a 12V DC transformer (for LED lights), but that has two (black and red) wires.

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What is the issue? Have you read the instructions? Probably just need to use one or the other pair, or all 4. Don't know without seeing it.

What is this sensor you're installing. What is it's application. 

Don't see any issue with using a single cable? Unless you are using the volt free contacts at a higher voltage? In this case the cable insulation would have to be rated at the highest voltage used. 

Lurch said:

What is the issue? Have you read the instructions? Probably just need to use one or the other pair, or all 4. Don't know without seeing it.

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There aren't any instructions for the transformer, but this is the one:



And now i wonder whether the wattage matters (as this is rated 10W)?

Rob. said:

What is this sensor you're installing. What is it's application. 

Don't see any issue with using a single cable? Unless you are using the volt free contacts at a higher voltage? In this case the cable insulation would have to be rated at the highest voltage used. 

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The sensor is a Fibaro universal (wireless) sensor which will be connected to four tiny (UFH) floor temp. sensors:
http://manuals.fibaro.com/binary-sensor/

europa said:

There aren't any instructions for the transformer, but this is the one:

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I'm lost then, there's only 1 set of wires. More than likely fine just using one pair and making the other one safe.

europa said:

And now i wonder whether the wattage matters (as this is rated 10W)?

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Well yes, the wattage is the output power, so is whatever you are powering less than 10W at 12V?

You need to assess whether the power supply is stable at the low power your sensor is likely to use - it may only be a couple of watts. I'd connect a 100 ohm, 2 watt resistor to the PS and measure the voltage across it (you could get away with a 1/4w resistor for a few seconds for testing purposes).

cheers, Paul

europa said:

I need to install a sensor which requires a "9-30V DC +/-10%" supply. Clearly i need to buy a transformer to step down the mains voltage, but does 9-30V mean the transformer could be, say, 12V or 24V, i.e. anything between 9 and 30V? Or does 9-30V mean something else? FYI, the sensor only has one wire for power - see attached pic.

View attachment 8678

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The +ve (usually red) goes to '+9 - 30V'

The -ve (usually black) goes to the 'GND' next to +ve

Higher voltage travels further if there is any real distance between power supply and sensor. plus the sensor is likely fixed power so higher voltage means less amps drawn for same power. If the power supply is near the sensor, just use 12v. Easy to get hold of.

This is the technical data for the sensor. As you see there is no mention of the power required. However, if the output can only carry max 150mA, am i right in assuming that the power requirement would be max. 150mAx12V=1.8W ?

Your photo doesn't seem to agree with the wiring diagram .   Photo shows    an LED   driver  ...  2 wires   input  90 - 250 V .........output  2 wires  / 12V / 10W /   constant voltage.  

a link to what you have would probably be better

scrap that, you already did...

europa said:

am i right in assuming that the power requirement would be max. 150mAx12V=1.8W ?

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Nope, that's the switchable load and it's unlikely to be related to the power consumed by the device. The manual implies the switching method is volt free via relay - not actually stated as far as I can see - so the power consumption will change when the outputs are "on".

cheers, Paul

europa said:

This is the technical data for the sensor. As you see there is no mention of the power required. However, if the output can only carry max 150mA, am i right in assuming that the power requirement would be max. 150mAx12V=1.8W ?

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No, or maybe a bit. That could be per output so might be 300mA, but then the unit itself will still take some power so even if you had 15mA per output you would still need to account for the device itself.

You're overthinking it anyway, just stick a 12VDC 1A power supply and be done with it (not a random cheap Chinese LED driver).

europa,

Welcome to the forum.

All the info you need is actually in the link you posted earlier in the thread.

Sidewinder said:

europa,

Welcome to the forum.

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They say the memory is the first thing to go!