Power metering

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SumnerBoy

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#1295937 2-May-2015 23:21

Using CT clamps and a voltage measurement I am getting within 1-2% of my Meridian bill over a full month. So accuracy is pretty good.

gzt

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#1295951 3-May-2015 00:09

There are many wireless/battery models available. Perhaps even most are.

RUKI

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#1299120 6-May-2015 14:31

Why to have so much trouble?
Why do you need to continuously monitor your power consumption?
Test it once for every tool/device/charger/appliance you have in the household and you are sorted. Took me less than 1/2 day to test everything and make a list.
Simple Belkin power meter which you plug in and plug device in question in it and it gives you all you need to know, even monthly, yearly estimations and if you put $/kw - you can even have it in dollars. Cost me $5 on special. RRP is about $60.

timmmay

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#1299126 6-May-2015 14:40

RUKI: Why to have so much trouble?
Why do you need to continuously monitor your power consumption?
Test it once for every tool/device/charger/appliance you have in the household and you are sorted. Took me less than 1/2 day to test everything and make a list.
Simple Belkin power meter which you plug in and plug device in question in it and it gives you all you need to know, even monthly, yearly estimations and if you put $/kw - you can even have it in dollars. Cost me $5 on special. RRP is about $60.

My motivation would be to discover the source of large bills. For example hot water costs more in winter for three reasons:
- Increased shower length
- Lower water temperature means more power required to heat water
- Lower water temperature also means less cold mixed in, using more hot water

Hot water can't be measured with a plug in meter. Under floor heating probably costs more in winter, but I really have no idea how much it costs as it's difficult to measure.

richms

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#1299132 6-May-2015 14:47

gzt: There are many wireless/battery models available. Perhaps even most are.

The wireless ones are only transmitting a periodic average current value and then relying on a fixed multiplier for voltage and assuming a 0.8 power factor. Way to be inaccurate.

10% shift in mains voltage will have more than 10% change in readings. Power factor of 0.8 is probably far too optimistic for most houses now other than resistive heating.

Richard rich.ms

gzt

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#1299143 6-May-2015 14:59

Even so, still useful as an indicator.

Aredwood

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#1299449 6-May-2015 21:00

timmmay:
RUKI: Why to have so much trouble?
Why do you need to continuously monitor your power consumption?
Test it once for every tool/device/charger/appliance you have in the household and you are sorted. Took me less than 1/2 day to test everything and make a list.
Simple Belkin power meter which you plug in and plug device in question in it and it gives you all you need to know, even monthly, yearly estimations and if you put $/kw - you can even have it in dollars. Cost me $5 on special. RRP is about $60.

My motivation would be to discover the source of large bills. For example hot water costs more in winter for three reasons:
- Increased shower length
- Lower water temperature means more power required to heat water
- Lower water temperature also means less cold mixed in, using more hot water

Hot water can't be measured with a plug in meter. Under floor heating probably costs more in winter, but I really have no idea how much it costs as it's difficult to measure.

Now that we know that you just want to measure usage of restive loads. A current clamp only device will be fine. And you could always remove the terminal cover on your hot water cylinder. And put a current clamp there.

Also do you know if the underfloor heating is on load managed or night rate power? If so you could put a current clamp in the meter box on the output of the load management relay. So you could get combined hot water and floor heating usage.

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gzt

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#1299533 6-May-2015 22:39

I sometimes think there is a market for very simple load monitor nodes just on/off logging provides a lot of diagnostic data for things like hwc and ufh and anything else on a thermostat or pressure control.

By gosh those ubiquiti current sensors are good value if you have the system. Wonder if they are standards based and if anyone has RE'ed them for open source monitoring.

Mantis

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#1305211 14-May-2015 15:25

Have 2 of the Ubiquiti current sensors at home. Using the Mfi software, it doesn't actually give much info, just the immediate current reading and a history graph. Doesn't give any stats like daily usage or anything as no voltage or power factor measurement.

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