This is an experiment to see the accuracy and drift between two Sangamo kWh meters and a test load which is a 2.4 kW electric heater.<br />Both meters are wired up in series.<br />The S200.31 meter is a 50 Hz meter<br />The J4S is a 60 Hz meter<br />I expect an error will occur as the PT coil in the 60 Hz meter will draw a larger excitation current, hence more Voltage flux and higher kWh readings.<br /><br />8 July 2011<br />Start readings were 50375 for both meters.<br />15 July 2011<br />Meter readings are 50490 and 50493 kWh. ( overall error about + 2.5% which is not bad at all ).<br />16 July 2011 The dc resistance of the PT coil of the 60Hz meter is 970 ohms. For now I have added a 3k3 five Watt resistor in series and see what happens.<br /><br />In my follow up video I will add extra resistance in series with the PT coil to have the voltage at around 5/6 of 240 Volts which is 200 Volts.<br /><br />I created this video with the YouTube Video Editor (http://www.youtube.com/editor)