Technogomzi Electrical Engineering Supervisor
Aim: To Calibrate LPF wattmeter by Phantom Loading. Apparatus: 1) Voltmeter - 300V Digital --> 1 2) Ammeter - 10A Digital --> 1 3) Phase shifting Transformer - 415V/15A --> 1 4) Auto Transformer - 240V/0-270V,10A --> 1 5) Power Factor meter - 230V,10A-Dynamometer --> 1 6) Wattmeter(LPF) - 230V,10A-Dynamometer --> 1 7) Connecting wires Procedure: 1) Keep connections as per circuit diagram. 2) Keep Auto Transformer in minimum position and On toggle Switch. 3) Vary the transformer at Power coil till voltmeter reads rated value. 4) Vary phase shifting transformer to set power factore at 0.2 lag. 5) Now slowly vary the auto transformer at Current coil in Steps. 6) Note the values of wattmeter at each step of current. 7) Repeat the above step till Ammeter reads rated current. 8) Calculate percentage of error. Plot the graph between current and percentage of error, keep current on X-axis and % error at Y-axis. Calculations: Wa = VxIxCosQ watts. Wm = watts. % error = [(Wa-Wm)*100]/Wm. Precautions: 1) Avoid loose connections. 2) Avoid parallax errors.
• 3) Keep wattmeter and P.F meter in parallel.
Result:
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# How do you calibrate single phase energy meter by phantom loading?

  The phantom loading is that no external load is connected in actual sense and the current and pressure coils are connected seperatly so that it will consume only less po… (MORE)

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  The phantom loading is that no external load is connected in actual sense and the current and pressure coils are connected seperatly so that it will consume only less po… (MORE)

# Why is LPF wattmeter used for no load test?

In case of no load only magnetizing current is flowing which is somewhere around 75 degree out of phase and so the power factor is very low.

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# Is a wattmeter required to measure the active power delivered to a resistive load?

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# What is LPF?

LPF is Low power factor, which is used to calculate overall power in VA (voltamps) kind of like calculating overall power in watts.

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