Measurement of Energy by a single-phase Energy Meter

Experiment No: 13

Aim of the Experiment:

Measurement of Energy by Single Phase Energy Meter.

Objective:

To be written by student.

Apparatus Required:

Sl. No.Equipment NameSpecificationMakeQuantity
1Energy MeterAnalog, 230V, (5-10)A, 50Hz, 1200r/Kw-h1 Nos.
2Stop WatchDigital Type1 Nos.
3Load UnitResistive Type.1 KW.
4Connecting WiresPVC Insulated CopperAs per requirement
5Wattmeter(0-400)W, (5A/10A), UPF 1 Nos.
Table No: 13.1

Circuit Diagram:

Fig. 13.1

Theory:

In the energy meter, current coil carries current proportional to the load current. Where as the pressure coil carries current proportional to supply voltage.

\[\color\green{Average\; deflecting\; torque}\;\color\red{(T_d)}\;\color\magenta{ ∝} \;\color\red{Average\; Power} \] \[ \color\red{T_d\;}\color\green{∝}\color\red{ V\;I\;Cos\phi} \] \[\color\red{T_d}\color\green{=}\;\color\red{K_1\;V\;I\;Cos\phi……………..(i)}\]

consider the resistive load, then Cosφ=1

The breaking torque(Tb) is proportional to the disc speed N

then,

\[\color\red{T_b}\;\color\green{∝}\color\red{\;N}\] \[\color\red{T_b}\;\color\green{ =}\;\color\red{ K_2\;N…………….(ii)}\]

The disc achieves steady speed N, when Breaking torque (Tb) is equal to the deflecting torque (Td)

thus, from equation (i) and (ii)

\[\color\red{K_2\;N}\;\color\green{ =}\;\color\red{ K_1\;V\;I\;Cos\phi}\] \[ \color\green{multiplying\; both\; side\; by\; time\;}\;\color\red{ t,}\color\green{\; then}\] \[\color\red{K_2\;N\;t}\;\color\green{ =}\;\color\red{ K_1\;V\;I\;Cos\phi\;t}\] \[\color\red{N\;t\;}\color\green{ =}\;\color\red{ K_3 \;P\; t\: }\] \[\color\green{where,}\;\color\red{ P}\;\color\green{ =}\;\color\red{ V\;I\;Cos\phi,\, K_3}\color\green{=}\;\color\red{ \dfrac{K_1}{K_2 }}\]

since the product N*t represents the number of revolution of the disc in time t and the product P*t represents the energy passing through the meter in time t. Therefore, the number of revolution of the disc is proportional to the energy passing through the meter.

Procedures:

(i) Connect all the instruments as per circuit diagram.

(ii) Make sure i.e all instruments are showing zero error.

(iii) Start the power supply and start the stop watch simultaneously.

(iv) Note down the energy meter reading and calculate theoretical energy from the readings shown in wattmeter.

(v) Calculate the percentage of error.

Observation Table:

Sl. No.Power in WattsTime observed in consuming 0.1 units energy (in Hour)
(a)		Previous reading of energy meters
(b)		Successive reading of energy meters
(c)		 Difference reading of energy meters
d=(c-b)		Wattmeter reading(in Kw) (e)Theoretical Energy (in Kwh) (f=a*e)% Error
[(d-f)/d]*100
1
2
3
4
5
6
7
Table No: 13.2

Precaution:

  1. Make sure all instruments connection should be properly as per circuit diagram.
  2. Verify your circuit connection to your concern teacher before switch on the supply.

Conclusion:

To be written by students.

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