2. Single-phase AC meters. Practical implementation

2.1 Principle

A flux due to a voltage circuit and a flux due to a current circuit, one of which is out of phase with the other by π / 2 and whose action domains have a common part, act on a non-magnetic metal disk braked by a permanent magnet and free to rotate indefinitely around an axis by driving a timer.

The layout generally adopted is shown schematically on figure 11 . The electromagnet or motor element can take many different forms. Figure 12 shows the one used in a particular meter.