One has to calculate the real "environmental cost" (which is more & will be paid dearly by our future generations) as compared to just utility bills.
Back to the topic- I've seen cheaply built traffos having thermal runaway problems leading to burnt windings when not loaded or only secondary disconnected by switch as reported by Andrew T.
Also back in our college days during electrical eng. labs we used to draw eta curve (efficiency curve) for traffos using various dummy loads. The results were (if my memory serves me right) 50% to 95% efficiency under various load conditions.
Back to the topic- I've seen cheaply built traffos having thermal runaway problems leading to burnt windings when not loaded or only secondary disconnected by switch as reported by Andrew T.
Also back in our college days during electrical eng. labs we used to draw eta curve (efficiency curve) for traffos using various dummy loads. The results were (if my memory serves me right) 50% to 95% efficiency under various load conditions.
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The printer also has a switch. So does the monitor. Both are soft touch and therefore leave the supplies running. So does the computer. And the TV, and. . .
We're probably not going to run all over the house unplugging everything.
Therefore I recommend upgrading the room wiring to switch off all outlets, except for the fridge.
P.S.
Here in the USA, the big green colored dual channel switch at Lowes is probably strong enough for this approach. It has survived my hot water heater. So far, with some of the ZuniDigital smart sticks and increasing the number of rooms that switch off completely, the average bill has decreased $43 monthly, despite the electric company raising the rates. The sturdy switches and smarts sticks paid off in 2 months.
Disconnecting is highly effective! Not much else is.
Found out that ceiling level insulation is ineffective, but roof level insulation is highly effective. Currently working on adapting climate controls to a zone system because the garage doesn't need air-conditioned while I'm asleep or out. Also investigating the windows, both the frame and panes to non-thermally-conductive materials instead of the aluminum and glass that are easily identifiable as errors.
When it comes right down to it, there's a LOT of easily identifiable errors that run up our bills.
They are individually small and very numerous. So, catching all those many little errors isn't easy.
We're probably not going to run all over the house unplugging everything.
Therefore I recommend upgrading the room wiring to switch off all outlets, except for the fridge.
P.S.
Here in the USA, the big green colored dual channel switch at Lowes is probably strong enough for this approach. It has survived my hot water heater. So far, with some of the ZuniDigital smart sticks and increasing the number of rooms that switch off completely, the average bill has decreased $43 monthly, despite the electric company raising the rates. The sturdy switches and smarts sticks paid off in 2 months.
Disconnecting is highly effective! Not much else is.
Found out that ceiling level insulation is ineffective, but roof level insulation is highly effective. Currently working on adapting climate controls to a zone system because the garage doesn't need air-conditioned while I'm asleep or out. Also investigating the windows, both the frame and panes to non-thermally-conductive materials instead of the aluminum and glass that are easily identifiable as errors.
When it comes right down to it, there's a LOT of easily identifiable errors that run up our bills.
They are individually small and very numerous. So, catching all those many little errors isn't easy.
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But at least in the UK domestic users pay for real power not apparent power, so the question then is how much of that 34VA is real and how much of that is purely reactive?
Most of that 34VA is **NOT** dissipation!
My betting is that only about 10% or so of that is real power, with the rest being reactive.
Regards, Dan.
Most of that 34VA is **NOT** dissipation!
My betting is that only about 10% or so of that is real power, with the rest being reactive.
Regards, Dan.
These values are crazy, Andrew, that little tranny must be severly underwound.
FWIW a scope pic of a 230V/100VA type, China as well, from a consumer hifi. Test voltage was 250Vac, open secondaries. The transformer was humming audibly at this levels. While basically the idle current is inductive, once the core saturates inductivity decreases, making the current dissipating some real watts in the coil winding resistance while total power is some 10VA. The current peaks are not symmetric to the voltage zero crossings spaced 2 divs apart around the trigger.
Attachments
The transformer is stamped as 230V.
It appears that DAN have selected a 230V transformer that is possibly not a universal 220/240Vac unit to save costs.
When used on UK's 240Vac which can vary from 226Vac to 254Vac, that the transformer has gone into saturation at the upper end of the working voltage range.
It appears that DAN have selected a 230V transformer that is possibly not a universal 220/240Vac unit to save costs.
When used on UK's 240Vac which can vary from 226Vac to 254Vac, that the transformer has gone into saturation at the upper end of the working voltage range.
Many times a 115VAC/230VAC, (or 120/240 for that matter) are exactly the same.
Its very common practice.
UK voltage is unlikely to be quoted as 230 VAC anymore, unless in error. 240-250VAC is the case nowadays.
Our voltage was only ever quoted as 230VAC to align with European AC, since we buy so much of it....
For what its worth, my mains voltage here dips to its lowest at 6am, at 240VAC. Mostly I get 245-255VAC.
Now IF the trafo is 60hz rated then perhaps......
And not forgetting power quality. Lots of harmonics in the mains doesn't help either. Maybe the trafo is rated at pure sine VAs (a joke here) or the core lams are naff steel, or badly insulated. I.e. Daft amounts of coreloss, even before copperloss is factored in.
Since you're measuring a high idle current with the secondary winding OC then it indicates significant iron loss, and NOT copperloss, and an inefficient core, bad lams etc.
Regards,
A trafo abuser in my 9-5
Its very common practice.
UK voltage is unlikely to be quoted as 230 VAC anymore, unless in error. 240-250VAC is the case nowadays.
Our voltage was only ever quoted as 230VAC to align with European AC, since we buy so much of it....
For what its worth, my mains voltage here dips to its lowest at 6am, at 240VAC. Mostly I get 245-255VAC.
Now IF the trafo is 60hz rated then perhaps......
And not forgetting power quality. Lots of harmonics in the mains doesn't help either. Maybe the trafo is rated at pure sine VAs (a joke here) or the core lams are naff steel, or badly insulated. I.e. Daft amounts of coreloss, even before copperloss is factored in.
Since you're measuring a high idle current with the secondary winding OC then it indicates significant iron loss, and NOT copperloss, and an inefficient core, bad lams etc.
Regards,
A trafo abuser in my 9-5
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The "environmentalist cost" is much higher than that, and is mostly fraudulent waste, with a lot of waste heat dissipated orally, resulting in the only actual cause of any anthropomorphic global warming.
if you are seeing (real) supply voltages this high then you can ask the supplier to check your voltage and if correct demand that they take steps to bring your supply within the tolerance range that they MUST adhere to.
I am typically on 244Vac to 246Vac. I have never (yet) seen 250Vac or more.
254vac sounds reasonable, my bounds of voltage ate from memory....from what o know the regulation of frequency is by far the priority, as far as generating is concerned.
With the large increase in power management, converters and the like, i wouldn't like to guess what the harmonic content is like, but i imagine it has changed somewhat. With PWM carriers of several hundred Hz, I would think harmonics are quite bad, however i do know from experience that targeted filters are used to attenuate the worst harmonics. What's left? Haven't a clue. Must try to get the Voltec on one the next time one comes in for load tests.
With the large increase in power management, converters and the like, i wouldn't like to guess what the harmonic content is like, but i imagine it has changed somewhat. With PWM carriers of several hundred Hz, I would think harmonics are quite bad, however i do know from experience that targeted filters are used to attenuate the worst harmonics. What's left? Haven't a clue. Must try to get the Voltec on one the next time one comes in for load tests.
Is, perhaps a "made for 60hz" transformer running on 50hz instead? That could get hot.
Mooly, not quite sure what that tells me tbh. If there was a harmonic analysis i missed it lol. Though, as usual I'm probably just missing the point entirely lol.
I work in energy generation lol. Last year i finished a case study of UPFC, UTLC, B - B VSCs and grid load management. In particular the use if pumped hydro to load balance and correct for freq droop at peak load periods. Still would love to visit Denorwig (sp?) and see the systems in action.
So I'm still have much to learn, but have been privileged to see many things in this area.
I work in energy generation lol. Last year i finished a case study of UPFC, UTLC, B - B VSCs and grid load management. In particular the use if pumped hydro to load balance and correct for freq droop at peak load periods. Still would love to visit Denorwig (sp?) and see the systems in action.
So I'm still have much to learn, but have been privileged to see many things in this area.
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No mention of harmonics 
I just posted it with you mentioning frequency as being a priority.
Probably its a way of inferring how close the grid is to either collapsing under demand (or overvolting due to to much generation and not enough demand) by indirect means.
My guess would be that as the demand increases, and so to the loading on the generators, then they tend to slow. So you could infer from that, that if say the frequency had fallen to (say) 49 Hz, then the loading required to do that would have indirectly pulled the voltage down to (say) 180 or whatever and so lights go out. And the opposite when they are spinning to fast. That's just my take on it.
I just posted it with you mentioning frequency as being a priority.Probably its a way of inferring how close the grid is to either collapsing under demand (or overvolting due to to much generation and not enough demand) by indirect means.
My guess would be that as the demand increases, and so to the loading on the generators, then they tend to slow. So you could infer from that, that if say the frequency had fallen to (say) 49 Hz, then the loading required to do that would have indirectly pulled the voltage down to (say) 180 or whatever and so lights go out. And the opposite when they are spinning to fast. That's just my take on it.
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