Electric Meter Parts Diagram

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In this topic, you study Energy Meter – Working, Construction & Diagram. Energy Meter is used for measuring the power consumption in kWh of a domestic or industrial electrical installation. The energy is the total power delivered or consumed during a time interval. The energy is product of power and time (E = P × t). Its unit is joule or watt second, which is equal to 1 watt over an interval of 1 second. If time is taken in hour. the energy is then expressed in watt hour (Wh). In many cases, wh is a small unit than kilowatt hour (kWh) is used and 1 kWh = 1 kW × 1 hr = 1000 W × 1 hr. The “Kilo watt hour” is also called as a “Board of trade (B.O.T)” unit in commercial sector.

The energymeter therefore is an instrument which can measure quantity of energy supplied to a circuit in a given time. The instrument is also called as “Kwh meter”. The basic principle of induction energy meter is electromagnetic induction. A thin disc of aluminium (or copper) is pivoted between the two Shunt and Series magnets and cuts the fluxes of both the magnets (Fig.

How the Electric Meter Monitors Power Usage

Reading the Meter

  1. The driving torque on the disc is produced as a result of interaction of the two inducing fluxes.
    Understand the parts of your analog meter (also known as a dial meter) and how it works. Your electric meter usually has between four and six dials that advance as a central disk turns.[1] The disk is turned by the electricity passing through the meter, giving a readout of how much electricity you are using. [2]
    • A “Brake magnet” produces a controlling torque on the disc, which has no pointer, as an energy meter is an integrating instrument and the disc has to rotate continuously so long the meter remains connected in the circuit.
    • Driving system,. Braking system,. Recording system. The driving system is made of two electromagnets. It consists of a no. of V-shaped laminations Of silicon steel forming a core. A coil of thick wire and of few turns is wound on this magnet and is connected in series with the load.
  2. It carries line current and therefore called “current coil” (C C).
    This magnet produces a magnetic field proportional to and in phase with the line current. It consists of numbers of M shaped laminations of silicon steel assembled together as a core. A coil of thin wire large number of turns is wound on its central limb. The coil is connected across the load and carries a current proportional to the supply voltage and therefore called a “potential coil” (PC). Induction Type EnergyMeter. In order to obtain the driving torque on the disc, current in the P.C. must lag supply voltage exactly by 90°. For this one or more shading bands are provided on the central limb of the shunt magnet. The shading band has to be adjusted to the exact 90° phase difference. Since resistance of the shading band coil is bly small as compared to its inductance, therefore current in the band lags the voltage approximately by 90.
    When disc rotates in the magnetic field of the break disc cuts this field and (and thus eddy currents) is induced in the disc.
  3. The direction of eddy currents is opposite to the direction of rotation of the disc (lez’s law) and thus it controls the rotation.
    As the eddy currents are proportional to the disc speed, so the braking torque is also proportional to the disc speed. The amount of Braking torque can be adjusted by adjusting the position of the braking magnet. If the braking magnet is moved towards the centre of the disc the flux cut by the disc is reduced and so reduces the induced currents and the braking torque.
  4. This will increase the speed of the disc.
    Reverse happens if the break magnet is moved outward from the disc. The function of recording system is to register/count the no. of revolutions made by the disc. By using a train of gears on the disc spindle, 5 to 6 pointers are driven. These pointers rotate on dials which are marked with ten equal divisions.
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Wrapping Up The Common House Electric Circuit

  1. shows a cyclometer type recording.
    Understand the different parts of your meter. A digital electric meter records the amount of electricity your household is using electronically. Thus, a digital electric meter is much simpler to read than a traditional meter because it has fewer readings to decipher.[4]
    • The disc may be taken as the rotor of the motor. shows another view of 1 phase energymeter. Pointer Type Recording. Cyclometer Type Recording. A View of Energy Meter. The energy meter will register correct energy only if the shunt magnet flux lags the voltage exactly by 90°. This requires that the pressure coil should be highly inductive. If the angle is not 90°, it is to be adjusted by shading bands provided on the central limb of the shunt magnet.
  2. Sometimes it is also called as “low power factor”/Quadrature or Reductive load adjustment.
    The adjustment is done by moving the shading bands (Fig. 5.) along the axis of the central limit:. As the bands are moved up the limb they embrace more flux. This results in greater induced emf and current produced by the bands therefore, the value of “lag” angle increases. When the shading bands are moved down. The limb induced emf and current decreases and the “lag angle” also decreases. The adjustment is done in such a way that the angle of lag is exactly 90 i.e., is brought exact in quadrature with the voltage. Few errors which are common in induction energymeter are described below :. Normally the flux due to shunt magnet does not lag the supply voltage exactly by 90°. The reason being that the shunt coil has some resistance. Due to this, the angle of phase is less then 90°, as a result, the torque on the disc is not zero at zero power factor. It is adjusted by adjusting the position of shading bands on the central limb of the shunt magnet. If the disc moves faster or slower, it is called as “speed error”. If the disc moves faster it will give a higher reading and viceversa. This error may be compensated by moving the brake magnet towards or away the centre of the disc.
  3. Basic Household Electrical Parts & Materials

    With rated supply voltage, rated full load current and unity P.F. the speed of the disc is checked. Now full load unity P.F. and lag (low P.F.) adjustments are repeated till the desired accuracy is obtained for both the conditions. Load adjustment. Light load adjustment: Rated supply voltage is applied across the pressure coil and a very low (5% of the full load) current is passed through current coil at unity P.F. The meter should move at a correct speed even at light load. Full load and light load adjustments at unity P.F. are repeated till correct speed is obtained at both the loads. Re-check the performance of the meter at 0.5 P.E. Creep adjustment. The pressure coil is excited at 110 percent or the rated voltage with zero load current. The meter should not “creep”. Frictional adjustment. The frictional error in the induction type energymeter is compensated by placing shading (short circuiting) bands at the side limbs of the shunt magnet. Meter forms, or the form number on an electric meter are the numbers that help us as meter techs determine what type of meter should go in a particular service. There are a variety of form numbers that are used. There are also basically two types of services that metering installation will have. The most common is self-contained. The other is transformer-rated. The difference between the two is that that the transformer-rated service uses CT’s whereas the self-contained service does not. Blondel’s Theorem is typically used to determine what type of meter to install in each different type of service. Here are the most common and the most common service types that they are used in. A form 1s meter a meter that was commonly used in single phase, 120v two wire services. While there are still many 1s meters out in the field and there are utilities who still buy them, they are not nearly as common as they once were. The reason being that many homes that used this type of service converted to 240v either because they upgraded or because they were forced to by their utility. Utilities wanted to make the switch because it is so easy to put a 240v form 2s meter in a 1s socket. The two meters, to the naked eye, look identical. Without reading the nameplate it is hard to distinguish the difference. The meter base for a 1s is also wired differently than a 2s. However, an untrained eye may not catch this difference and install a form 2s meter by accident. Also, many utilities decided to convert many of the 120v services to 240v just so they could install a 2s meter. There is no difference for the customer as they still see 120v. There are just no wires connected to one of the load side terminals of the meter base. The most common use for the 1s meter now is for sign services which only require 120v. The form 2s is by far the most common meter form out there. This meter is most commonly used in a 240v, single phase three wire service. This is the meter that most people will find on their homes. This form is also used for many small businesses as well. Click here for a form 2s meter wiring diagram. Form 3s meters are typically used for single phase two wire services where the service is so large that it requires CT’s. They can also be used for three wire single phase services as well as single phase primary metering. A form 3s meter uses one CT.
    They will then tighten down the screws and tug on the wires to ensure the connections are tight.
    In some systems, the hot feed wires are two black wires, while in other systems there will be a black and a red wire.
    The load side of the electric meter, which carries power to the main service panel, can be wired either directly to the panel or to an interim disconnect.

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Anatomy of an Electric Meter

To do this, the ends of the two hot load wires are stripped and connected to the bottom two load terminals on the meter's hot bus bars.
Again, the technician will tighten the screws and tug on the wires to make sure the connections are secure.
Along with the hot and neutral wires, the system includes a separate grounding wire that leads from the meter box to a grounding rod buried in the earth.
The ground wire is connected to the ground terminal in the center of the meter, which is bonded to the neutral bus bar.
The other end of the ground wire attaches to a grounding rod via a fitting known as a grounding lug.
To effectively protect this ground wire, the technician may run the grounding wire through a hollow metal conduit to the grounding rod buried in the earth.
Without this protection, the ground wire can be damaged by a lawnmower or weed trimmer.
The final step is connecting the neutral line and load wires, which are typically marked with white tape to identify them as neutral.
The technician strips and attaches these neutral wires to the top and bottom terminals on the neutral bus bar in the center of the meter box.
After tightening the screws firmly with a screwdriver, the technician tugs on the wires to make sure they are secure.
The technician now attaches the meter mechanism, closes and locks the meter, and then turns on the power to the service wires and checks to make sure the meter runs correctly.
The electric meter exists so that the power company can monitor current usage and bill you accordingly.
The electric meter is usually a clear, glass-encased metering device resembling an oversize mason jar.
The glass dome houses the measuring devices that include dials and wheels on the older model meters, or a digital display on newer models.

Connect the Neutral Wires

  1. The meter not only measures power but also provides a way for the utility company can disconnect power from your home.
  2. Usually, there are five dials that measure kilowatts and a large rotating wheel that sits below them.
  3. This type of meter can be read by the owner of the property who reports the results.
  4. Or, the utility company will read it for you, sometimes for a charge.
  5. Newer electric meters are digital and are actually read from the utility company's office.
  6. A signal identifying your particular meter is sent down the service wires from the electric meter to the utility company.
  7. Electric meters read power usage in kilowatt-hours. In simple terms, 1-kilowatt-hour = 1,000-watt-hours.
  8. The meter reads the entire power usage (in watts) of all appliances, light fixtures, and plug-in appliances within the home.

1. Electric Meter

If your utility system requires it, once each month you will "read the meter."
The way you do this will depend on whether you have an older analog meter or a newer digital meter. On an analog meter, you will note the readings on five dials, from left to right, and copy these readings on the report to the power company. Generally, the pointers on the dial will be between numbers, and you will report the lower of the two numbers. If a dial's pointer is exactly on a number, check the dial immediately to the right. If it has not yet passed 0, you will read use a lower number for the reading of the previous dial. (Your utility company will have precise instructions for how to read your meter; in some cases, it may require you to simply copy the visual appearance of the dials, like drawing clock faces.) .
With a digital meter, reading the meter is a simple matter of writing down the numerical value shown on the digital readout.
Not all installations are created equal.
Search through our list of wiring diagrams to find the right one for your job.
Article SummaryX

To read a digital electric meter, read the series of large numbers near the center of your meter and write them down. If you wish to calculate how many kilowatt hours you’ve used in the last month, subtract the current reading from the previous reading, which should be stated on your most recent bill. For more tips on reading meters, like how to read analog electric meters, keep reading!

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3. Distribution Box

  • Learn the steps for a flawless installation from start to finish.

Errors in Induction Type Energy Meter

These days almost everybody uses electricity in their houses and work places.