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 meterbr The J4S is a 60 Hz meterbr 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 2011br Start readings were 50375 for both meters.br 15 July 2011br 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 56 of 240 Volts which is 200 Volts.