Single Phase Watt Meter

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In this topic, you study Single Phase Energy Meter – Working, Construction & Diagram.

A single phase energy meter is used for measuring the power consumption in kilowatt-hours (kWh) of a domestic or industrial electrical installation.

A single phase energy meter is a sort of induction type watt-hour meter. It consists of two electromagnets.

One magnet is called the shunt magnet Ml which is mounted with a pressure coil. The pressure coil is a long coil made of fine copper wire which is connected across the supply line.

Another magnet is called the series magnet M2 which is mounted with current coil.

The current coil is a short coil made of thick copper wire which is connected in series with the load.

There is a round aluminium disc which is placed between two magnets and it is mounted on a spindle.

The spindle rests on two pivots. A horse-shoe magnet is placed on one side of the disc to provide damping, as shown in Fig.

19: Single Phase Energy Meter. When the meter is connected to the supply line and the load, then both the coils produce their magnetic fields.

The field produced by the current coil is directly proportional to the magnitude of current flowing through it (or through the load, since it is connected in series with the load).

The field produced by the pressure coil depends on the voltage across it. Both the fluxes produce eddy currents in the disc.

Thus, we have two fluxes and two eddy currents and therefore two driving torques resultant produced on the disc.

Working of Single Phase Energy Meter


The damping torque is produced by the permanent magnet. Shading rings are mounted on the shunt magnet for the correction in power factor of the meter. The rotational speed of the disc is counted by a counting mechanism which may be of any one of the following types:.

Cyclo Dial : This system consists of many round discs each marked with 0 to 9 digits on its periphery.

All the discs are connected with gears to each other, as shown in Fig. The collective reading of all the discs shows kWh. 20 : Cyclo Dial System. Clock System : This system is identical to a clock. It consists of 6 dials each marked with 0 to 9 digits on its periphery.

The dials show thousand, hundred, ten, unit, 1/10th and 1/100th of a unit (kWh).
  • The last two dials are of red color, as shown in Fig. 21 : Clock Dial System.
  • Number Dial : This system consists of seven geared rings each marked with O to 9 digits on its rim.
  • All the rings together show the reading in kWh.
  • 22 : Number Dial System. I am using this to measure how much electricity is going to my electric vehicle charger.The Good: It works for what I need ( 1 week ) so far and is very inexpensive.

Related Topics


Accepts 240V ( 2 Hot Wires ) w/o neutral or ground even thought the diagram on it looks more like 120V setup. The lugs are large enough and tighten up enough for it to conduct the amperage it is rated for. I used #6 wire because I am only running 40A through it max. It fits inside a cheap metal enclosure ( Halex HNF60R ) with a cutout for the display.The Bad: This is not UL listed so I am not confident that it will not melt and catch fire.

I originally purchased a plastic electrical box with clear cover for this but decided a metal enclosure would be a little safer.

Instructions are not great but if you understand electrical and have the confidence to ignore the diagram and put one Hot to L-IN side and the other Hot to N-IN ( to make a 240V circuit ) then you will be fine.
  • The front clearly states 230V rating so that is what I am trusting here.
  • This is a 7+1 digits meter that shows the total power consumption.
  • Good brand reputation.

Construction of Single Phase Energy Meter


The Astibym Single Phase Electric Meter‘s high-end materials make sure that it ages well with use. The astibym single phase electricmeter is 7+1 digits meter shows the total power consumption. Make sure this fits by entering your model number. In addition, the meter has good anti electromagnetic interference, low power consumption, high precision, high overload, high stability, anti electricity stolen and a long life.

The meter has a lcd display and it is lightweight. Above all, the astibym singlephase electric meter is suitable for the measurement of rated frequency of 50 hz single phase ac active electricity, etc.

Why We Like This:
  • The meter can directly and accurately measure active energy of the energy consumption.
  • It features high reliability, small volume, light weight, beautiful appearance, advanced technology, etc.
  • Lot of satisfied buyers.

Best For Beautiful Appearance: Nannigr Single Phase Electric Meter


Why We Like This:
  • This is rated current and it has a lcd display.
  • The Lcd display is 5+1 meters and shows the total power consumption.
  • Good investment for the long term.

Best For Small Volume: Jeankak Single Phase Electric Meter


The Jeankak Single Phase Electric Meter is capable of outshining several other meters featured in this list in overall features for the price point. The jeankak single phaseelectric meter can directly and accurately measure active energy of the energy consumption. Make sure this fits by entering your model number. And, it has good anti-electromagnetic interference, low power consumption, high precision, high overload, high stability, anti electricity-stolen and a long life.

The meter is 7+1 digits meter shows the total power consumption. Lastly, the jeankak singlephase electricmeter is suitable for the measurement of rated frequency of 50 hz single-phase ac active electricity, etc.

  • It features high reliability, small volume, light weight, beautiful appearance, advanced technology, etc.
  • It has an LCD display and it is lightweight.
  • Good brand reputation.

Best For Power Supply: Cetpmc Single Phase Electric Meter


We would, of course, be remiss if we didn’t mention Cetpmc Single Phase Electric Meter for daily purpose. Make sure this fits by entering your model number. Further, the meter has a lcd display and it is suitable for power supply. When it comes to searching for an optimal meter, the cetpmc single phase electric meter is definitely your first choice.

Why We Like This:
  • Delivers what they promise.
  • Good investment for the long term.

Best For Low Power Consumption: Zylm5252 Single Phase Electric Meter


The Zylm5252 Single Phase Electric Meter‘s high-end materials make sure that it ages well with use. Also, it has the characteristics of high reliability, small size, light weight, beautiful appearance, advanced technology, 35mmdin standard rail installation, etc. Zylm5252 offers a variety of meters for personal choice and yet maintains quality in all the variants. Most importantly, the zylm5252 single phase electric meter has good anti-electromagnetic interference, low power consumption, high precision, high overload, high stability, anti-theft.

  • Good brand reputation.
  • One of the newcomers and featured product.