Method and apparatus for testing the operating conditions of an electric network

A method for testing the operating conditions of an electric network, the conditions comprising at least one operating state, the electric network comprising at least one load, the method comprising the steps of:

• providing an instantaneous current signal (i(t)) to the load,
• measuring a voltage signal (v(t)) to the ends of the load,
• said method being characterized in that it comprises the additional steps of:
• delaying the voltage signal (v(t)) by a predetermined amount of time (τ) to generate a delayed voltage signal (v(t+τ)), the predetermined amount of time (τ) being a function of the operating state of the load),
• calculating, within a predetermined measurement time (Tm), an impedance ratio (Zχ(τ)) between the mean of the product of the delayed voltage signal (v(t+τ)) and the instantaneous current signal (i(t)), and the mean of the square of the instantaneous current signal (i(t)),
• comparing the value of the impedance ratio (Zχ(τ)) with a range of predetermined values (Zmin,Zmax) to determine the at least one operating state of the electric network.

A device (10A) for testing the operating conditions of an electric network, the conditions including at least one operating state, the electric network having at least one load, the device comprising:

• a circuit (11) for generating a voltage signal (v(t)) to be provided to the load, measuring the instantaneous current signal (i(t)) circulating in the load;
• a selector for selecting a predetermined amount of time (τ) as a function of the operating state to be tested,
• a circuit for generating an instantaneous current signal delayed (i(t+τ)) by the predetermined amount of time (τ) as a function of the selected operating state,
• a processor operating within a predetermined measurement time (Tm) and configured to process an admittance ratio (Gχ(τ)) between:
• the mean of the product of the voltage signal (v(t)) and the delayed instantaneous current signal (i(t+τ)), and
• the mean of the square of the voltage signal (v(t));
• and
• a comparator for comparing the value of the admittance ratio (Gχ(τ)) with a range of predetermined values (Gmin,Gmax) to determine the at least one operating state of said electric network.

A device for testing the operating conditions of an electric network, including at least one operating state, the electric network having at least one load, the device comprising:

• a circuit for generating an instantaneous current signal (i(t)) to be provided to the load and measuring a voltage signal (v(t)) to the ends of the load
• a selector for selecting the at least one operating state of the load (L),
• a generator for generating a voltage signal delayed (v(t+τ)) by a predetermined amount of time (τ) as a function of the selected operating state,
• a processor for calculating, within a predetermined measurement time (Tm), an impedance ratio (Zχ(τ)) between the mean of the product of the delayed voltage signal (v(t+τ)) and the instantaneous current signal (i(t)), and the mean of the square of the instantaneous current signal (i(t)),
• a comparator for comparing the value of the impedance ratio (Zχ(τ)) with a range of predetermined values (Zmin,Zmax) to determine the at least one operating state of the electric network.

A method, comprising:

• providing a voltage signal to an electric network having at least one operating state, the electric network including at least one load;
• measuring the instantaneous current signal circulating in the load as a result of providing the voltage signal;
• generating a delayed instantaneous current signal that is delayed by a predetermined amount of time that is a function of an operating state of the load;
• calculating within a predetermined measurement time an impedance or admittance ratio;
• and
• comparing the value of the impedance or admittance ratio with a range of predetermined values to determine at least one operating state of the electric network.

A circuit for testing operating conditions of an electric network having at least one operating state and coupled to at least one load, the circuit comprising:

• a first circuit adapted to generate a voltage signal to be provided to the load and to measure an instantaneous current signal circulating in the load as a result of the generating of the voltage signal;
• a selector circuit adapted to select a predetermined amount of time;
• a second circuit adapted to generate an instantaneous current signal that is delayed by the predetermined amount of time;
• a processor operating within a predetermined measurement time and adapted to process an impedance or admittance ratio;
• and
• a comparator adapted to compare the value of the impedance or admittance ratio with a range of predetermined values to determine the at least one operating state of the electric network.