Measuring Power Consumption Of 230VAC circuit?

[radios1]

My electric meter has digital readout too, but it is in Watt-hours consumed. It does not indicate the power being currently used.

it does. P=E*I which is the power = the voltage*the current. you get billed for kilowatt hours, not power anyway it's related, but not the same.. it's easy to measure the voltage and the current separately..

 

[npalen]

There seems to be a lot of confusion between watts and kilowatt hours.

 

[Smokeydog]

Which model of mini split?

It would be fun see what every appliance consumes. Limitations of metering equipment vs cost, power factor considerations make measured data messy.

My Mitsubishi is 240v but fan motors and compressor are dc for variable efficient control to meet the conditions. Cycles on/off in heating mode, never blows cold (room temperature) air. Easily produces 3x the heating power than electricity consumed. Marvel of engineering. Extracting solar power more efficiently than PV. Essentially heat my home with solar via a heat pump.

My power company bill has graphs and numbers of the past year by months of power consumed. Three meters on the farm, separate bills, gives some indication of equipment usage.

Being able to see my power meter reading real time and over time in an app doable? Anyone doing this?

Interesting discussion. We all should be cognizant of what we use and how to conserve energy.

 

[Chewwy]

it does. P=E*I which is the power = the voltage*the current. you get billed for kilowatt hours, not power anyway it's related, but not the same.. it's easy to measure the voltage and the current separately..

??? Not clear what your message is intending to convey.

 

[npalen]

Ours is a Lennox MLA one ton with MWMA inside wall mount unit. It is 240V and inverter technology which I assume to be AC motors. There is a parameter controlling whether the inside fan motor that circulates when the compressor is not running and have considered setting that to "off". The idea, from my understanding, is to give a more uniform air temperature to the sensor which is internal to the air handler.

The irony of that is I've been having an issue with the internal sensor picking up hot air recirculating right back up into the unit and shutting off the compressor (short cycling). That is what instigated checking amperage with a recording amp clamp to see how often the cycling was occurring.

The short cycling can be prevented by using the hand held remote as the temp sensor and placing it at distance where its not susceptible to false readings. Its like a TV infrared remote so has to be aimed and then left in that position to communicate with the air handler which talks to the outside (compressor) unit.

The MLA model number identifies it as "Low Ambient" and is supposed to extract heat from the atmosphere as low as -20F degrees.

https://www.lennox.com/products/heating-cooling/mini-split-systems/mla

 

[Carl_NH]

Which model of mini split?

It would be fun see what every appliance consumes. Limitations of metering equipment vs cost, power factor considerations make measured data messy.

My Mitsubishi is 240v but fan motors and compressor are dc for variable efficient control to meet the conditions. Cycles on/off in heating mode, never blows cold (room temperature) air. Easily produces 3x the heating power than electricity consumed. Marvel of engineering. Extracting solar power more efficiently than PV. Essentially heat my home with solar via a heat pump.

My power company bill has graphs and numbers of the past year by months of power consumed. Three meters on the farm, separate bills, gives some indication of equipment usage.

Being able to see my power meter reading real time and over time in an app doable? Anyone doing this?

Interesting discussion. We all should be cognizant of what we use and how to conserve energy.

We have three Mitsubishi Hyper Heat Mini Splits 2 - 9K and one 12K (1 Ton) installed powered by the separate garage service and meter with installed 7.2KW Solar and the 9K units are 30 SEER and the 12K is 26 Seer they are very efficient units.

We have the solar edge optimizers/inverter which provides output by day/month and I use this to compare against the electric bill. It's pretty easy to determine month to month KW usage of the Mini Splits as i know the historical base line energy KW for the garage is 130KW/month without the mini splits - the balance goes to the mini split heat/ac in summer/winter.

As far as Npalen and your Lennox MLA unit - it appears your indoor head is mounted close to a window/door in the corner of the room which could lead to uneven distribution causing the cycling. Generally speaking you want it on a wall close to the middle of the room for even air distribution. Does the Lennox MLA have a air directional flow capability to send more air to the right/left?

The Mitsu units you can set up the directional air flow to left/right etc. in case of a comer mount location, so if they have this capability try this to minimize short cycling.

 

[npalen]

Yes, the Lennox has directional flow which is now set to direct airflow to the center of the room. It also has the louver on the front of the unit which can be auto cycled to oscillate full down to straight out or manually set with the remote to any position.

I'm a bit concerned that the one ton unit might be a bit oversized for summer cooling. The room is only 168 square feet but it does have double pane glass all the way around the 10'x14'. The glass is certainly nice with the south sun this time of year and/but the southern exposure won't see any sun during the hot months.

The inverter technology might alleviate the oversize concerns hopefully. My contractor recommended a 1.5 ton unit but that would seem to be way overkill for the small room.

 

[Carl_NH]

Wow - that's a big unit for that small of a space - our 9K units heat/ac 700 SF on average, and the 12K unit is on 1000 SF area.

That might be the reason for cycling.

 

[Mendonsy]

+/- 10% of what. Full scale?

Percent of full scale is typical for a lot of instrumentation.
+/- 10% is not that great.

That's the point!!
They might not be quite as bad as 10%, but you can't simply plug one in and expect real accuracy. About the only way to solve that issue is to measure the reading against a precision meter at low, mid, and high readings to develop an accurate scale. I have had similar experience with analog pressure and temperature sensors connected to a PLC. Those require the actual reading to be multiplied by a gain factor with an offset factor added in to get a correct reading.

 

[npalen]

Wow - that's a big unit for that small of a space - our 9K units heat/ac 700 SF on average, and the 12K unit is on 1000 SF area.

That might be the reason for cycling.

We can leave the patio door open so the mini split will actually help cool the house which, with it's 3 ton unit for 1600 sqft, can be a little short on the hottest summer days. Air movement will be key, I'm guessing.