Last nights DIY SOS

[stef]

afternoon chaps,

has anyone seen last night's DIY SOS, the episode with the eco house? They used a mains step down unit
to lower the power consumption (by lowering the supply voltage) to 220 V. This unit seemed to me very light
weight so it can't be a step down transformer so I assume it must be a MOS FET stack which is triggered
by a sine signal. A switch mode PSU would be inappropriate for a mains supply.
Has anyone any experience with such a unit? (efficiency, price, noise, heat)

TA

 

[Knobhead]

There’s always two sides to an argument, this is from the Carbon Trust about a company I used to deal with Buxton Press - case study

 

[rocker]

Ah now it makes sense to me! I thought you were saying that you can drop the volatge, keep the same wattage output and save, which just doesn't add up!

Just seems like a surefire way of knackering equipment to me. The only thing you're really going to save on is lightbulbs, which will be dimmer, so why not save a lot of time and effort and buy lower wattage bulbs!?

 

[davelerave]

There’s always two sides to an argument, this is from the Carbon Trust about a company I used to deal with Buxton Press - case study

ya that's more like it 230v -if you're up about 240v or more

more power-more savings

 

[DurhamSparky]

wonder how much the 220 v gadget costs vs the savings!! lol

 

[Knobhead]

220 Vs 230V
How about 220 / 440 / 550DC 100 / 115 / 220 / 230 / 240 / 250 / 3KV / 11KVAC

Spare a thought for our predecessors, I came across this while looking at the history of Mansfield. It starts with the first installation in 1899 East Midlands Electricity and Mansfield Corporation Electricity Department : History of Electricity

People complaining when the picture on their steam tele kept getting smaller and then vanishing due to volt drop.

 

[fozzy]

a 12v downlighter and a 230v downlighter each with a 50w lamp. no difference

 

[eggyboy]

afternoon chaps,

has anyone seen last night's DIY SOS, the episode with the eco house? They used a mains step down unit
to lower the power consumption (by lowering the supply voltage) to 220 V. This unit seemed to me very light
weight so it can't be a step down transformer so I assume it must be a MOS FET stack which is triggered
by a sine signal. A switch mode PSU would be inappropriate for a mains supply.
Has anyone any experience with such a unit? (efficiency, price, noise, heat)

TA

hope billy reched his cable calcs

 

[chrisreid186]

the idea seems pointless why not just buy a dimmer switch for the lights

 

[thewetspark]

Thing I've noticed, guys on site go through a lot of switches on their 110v power tools (heavy wattage ones), especially those who never worry about how many extension leads they're on so get excessive voltage drop. I put it down to Ohms Law, voltage goes down so amps go up to compensate to get the power, hence burn't switches. I've even done some practical tests with a voltmeter and clamp ammeter, which seemed to prove my thoughts.

 

[matty-tattie]

this was on diy sos tonight as well, i wasn't sure about it because i thought a 50w lamp was a 50w lamp. hence- a 50watt lamp at 230v ac would draw a current of 0.217 amps, so would a 50w lamp at 220v ac not just draw a higher current of 0.227v to compensate for the lower voltage?

 

[Marvo]

Standard nominal supply voltage here is 220volts. I've logged our power and it drops at peak load times to 202volts and rises during low load time to a max of 222volts. All our appliances and lighting is rated at 220-240v. The only time I had a problem with the low voltage was with a gigabit ethernet switch that would reboot intermittently. I bought a stabilized power supply for it and it was okay after that. In general I would say that most devices are okay to run on anything above 200volts.

 

[Adam W]

I think the idea is that the resistance of an appliance is the same and it will work perfectly well on a voltage lower than the supply voltage, therefore the current is lower. Multiply that by the voltage and you're using less power.

Permit me to demonstrate:

I = V/R
I = 250/200
I = 1.25A

P = VxI
P = 250x1.25
P = 312.5W

Reduce the voltage...

I = 225/200
I = 1.125A

P = 225x1.125
P = 253.1W

 

[matty-tattie]

so in that case appliances wont work at their rated power output? there is a fair difference there with only a 25v change

 

[ratpig]

What can anyone tell me about "inductive voltages"? I remember something about Halogen spots pulling more current than standard lamps of the same power output from college. Also the same for transformers. Anyone offer any information on this?

 

[Des 56]

Those v phase things only have small befits when used with resistive loads
For that benefit to be of any use the distribution board would have to have the circuits segregated to supply only the resistive loads
At 300 or so a shot,it would take an eternity to recoup the outlay.but sales and marketing can do wonderful things for such drivel