[NTYNUT (OP)]

Hello
I have electricity meter digital with LCD what is inside it how it record data in it like energy date time what else please tell

[evan_au]

The electronic electricity meter contains a small computer that controls the LCD display, a memory that can store the computer program and records about your electricity consumption. There is a clock circuit which keeps time, even if the street power is turned off.

There is an electrical circuit which measures the electrical current drawn by your house, and also the AC voltage applied to your house. By multiplying together the instantaneous current and voltage, and adding it up ("integrating" is the mathematical term), it can measure how many kiloWatt-hours of electricity you have consumed.

There will also be a communication channel so the meter can be read and reprogrammed - this may be by plugging into the front of the meter, or wirelessly to a car driving down the street, or via a cellular network to the electricity company.

When a computer can read how much electricity you have consumed, and knows the time, it can do things like:
- Record how much electricity you have consumed in every 15 minute period for the past year
- Separately record electricity consumption during different periods of the day and weekends, so they can be charged at different rates
- Detect instances where household consumption has exceeded the maximum rating of the supply
- Measure how much electricity your solar panels are putting back into the network
- Any many other functions that would confuse the average homeowner, but are sometimes useful for businesses

I was involved in field trials of electronic meter reading in the USA & Australia, around 1990. The tiny computers, measurement electronics and communications systems have advanced considerably since then!

See: https://en.wikipedia.org/wiki/Electricity_meter#Electronic

[NTYNUT (OP)]

hello
how 3 phase electricity meter work

[evan_au]

how do 3 phase electricity meters work?

Pretty much the same as 3 single-phase meters:
- Single-Phase meters (common in Australia/UK) integrate Current x Voltage in 1 wire
- Two-Phase meters (very common in USA/Canada) integrate Current x Voltage in 2 wires
- Three-Phase meters (common in business and larger residences) integrate Current x Voltage in 3 wires

In the "old days", the measurement of Current x Voltage was done by magnetic fields rotating an aluminium disk (like a low-power electric motor); the arrangement and alignment of these magnetic fields became quite complex for a 3-phase meter.
- Today, this measurement is done by electronic circuits that measure voltage and current in each phase separately, and turn it into a digital value. This also allows measurement of the power balance between each phase, which is important for efficiency in delivering the power (especially to industry).
- This is part of a general trend to turn many types of signal from "analog"/"analogue" into "digital" for processing (even our nervous system does that, to some extent).

[NTYNUT (OP)]

Hello
Which processor do this calculation in it can we do it by simple 8051 processor

[evan_au]

Which processor do this calculation in it can we do it by simple 8051 processor

The meter I designed around 1990 did use an 8051-family microprocessor, with onboard A/D converter and 8-input analog input multiplexer. This was enough to measure 1 or 2 phase power (and could probably have managed 3 phase).

The processing power and memory of an 8051 microprocessor far exceeded the capabilities of the electromechanical meters that were in common use before then.

However:
- You ideally want to measure the current and voltage simultaneously, but you can't do this with a single A/D converter
- You ideally want to measure the current to at least 14 bits precision, but in those days you could not get integrated A/D converters of that accuracy
- You ideally want to measure the voltage and current at multiple points on every 50Hz/60Hz cycle, but the A/D converter was too slow
-  I was awarded some patents for overcoming these limitations...

But today, fast, multi-channel A/D converters with 16 bit accuracy (or more) are readily available; this article surveys a few of them:
https://www.digikey.com.au/en/articles/techzone/2012/jul/choosing-an-mcu-for-smart-energy-meters

Some reasons you would not use an 8051 chip today might include:
- It is very poor at doing 16-bit and 32-bit arithmetic. You really need a Digital Signal Processor.
- Hacking is more common today. You need secure encryption, and the 8051 is not suited for this task.
- A mass-produced special-purpose chipset will be the cheapest solution (which may incorporate an 8051 for some functions that are not very processor-intensive)
See: https://en.wikipedia.org/wiki/Digital_signal_processor

Less-obvious challenges to building an electronic meter might be:
- Plastic seems to be an obvious choice for a box, but lightning, electrical arcing, and sun exposure restrict the choice of plastics
- Extremes of temperature
- Different electrical and mechanical practices in different countries
- Communications technologies go obsolete in 10-20 years.
- Hacker capabilities grow rapidly
- Established vendors already in mass production.

One surprising discussion that took place with a US power company:
- Power Company: Can you turn off the little light at night?
- Me: Yes, it's controlled in software - but why?
- Power company: In some neighbourhoods, if someone sees a light at night, they keep shooting until the light goes out...

[NTYNUT (OP)]

Hello
I have seen meter in CT and PT at substation to measure power factor,reactive power etc