This circuit is for houses that have limited consumption.
The primary circuit represents 230vac net. Right resistors with switch represents home appliances and resistor with relay represents heater water tank for example (or something that consumes automatic and randomly).
The transformer represents a coil in the secondary circuit in which roll up 1 or 2 turns of primary circuit.
Then when we activate a high consumption device, relay off heater water tank thus prevent power outages for over current.
