Application of calibration wattmetre by phantom loding?

Answer 1

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:

Answer 2

When you are building a circuit of unknown reliablity then you will need to test it to find out if it works. The term bech testing is a method of building a ciruit, applying a dummy load and watching what happens. The Load used has the same electrical requirements as the real load but electronically simulates the real load. The circuit can then be tested by a Multimeter for Voltage Drop, Amps used, etc.