Method and apparatus for protecting an electrical load

An automation system having a load protection apparatus comprising:

• an overcurrent protection circuit having at least one input terminal adapted to receive a supply voltage from a power supply network or from a power distribution network and having a power switch through which the electrical load receives an electrical load current via the output terminal and having a current rise speed sensor component connected in series with the power switch and adapted to directly generate a voltage drop corresponding to the current rise speed of the electrical load current flowing from the input terminal of the load protection apparatus via the current rise speed sensor component and the power switch to the output terminal, the overcurrent protection circuit further having a driver circuit which is adapted to detect an occurring overcurrent depending on the voltage drop generated by the current rise speed sensor component and depending on a voltage drop along the power switch and which is adapted to switch off said power switch upon detection of an overcurrent within a predefined switch-off period, wherein the driver circuit is adapted to operate independently from a control unit of said load protection apparatus to provide protection against an overcurrent by switching off the power switch if the generated voltage drop plus a voltage drop along the power switch applied to a drive input of the driver circuit as a sum voltage exceeds a configurable threshold voltage;
• and
• said load protection apparatus further comprising an overload protection circuit having a load current sensor component adapted to continuously measure the load current flowing to the output terminal and to provide the measured load current to the control unit of the load protection apparatus, and further adapted to determine an overload state and/or a type of the connected electrical load on the basis of the measured load current profile, wherein the type of the electrical load comprises a resistive, inductive or capacitive load type,
• said automation system further comprising electrical loads connected to the output terminals of said load protection apparatus.

A method for protecting an electrical load connected to an output terminal of a load protection apparatus against overcurrent, said method comprising the steps of:

• receiving a supply voltage from a power supply network at at least one input terminal of an overcurrent protection circuit of said load protection apparatus, wherein the overcurrent protection circuit has a power switch through which the electrical load receives an electrical load current via the output terminal;
• generating directly by a current rise speed sensor component connected in series with the power switch a voltage drop corresponding to the current rise speed of the electrical load current flowing from the input terminal via the current rise speed sensor component and the power switch to the output terminal;
• detecting by a driver circuit of said overcurrent protection circuit an occurring overcurrent depending on the voltage drop generated by the current rise speed sensor component and depending on a voltage drop along the power switch;
• switching by the driver circuit the power switch upon detection of an overcurrent automatically off within a predefined switch-off period, wherein the driver circuit operates independently from a control unit of said load protection apparatus to provide protection against an overcurrent by switching off the power switch if the generated voltage drop plus the voltage drop along the power switch applied to a driver input of the driver circuit as a sum voltage exceeds a configurable threshold voltage;
• and
• continuously measuring, by a load current sensor component of an overload protection circuit of said load protection apparatus, the load current flowing to the output terminal and providing the measured load current to the control unit of the load protection apparatus;
• determining by the control unit an overload state and a type of the connected load on the basis of the measured load current profile, wherein the type of the electrical load comprises a resistive, inductive or capacitive load type.

A fuse housing having an integrated load protection apparatus, said load protection apparatus comprising:

• an overcurrent protection circuit having at least one input terminal adapted to receive a supply voltage from a power supply network or from a power distribution network and having a power switch through which the electrical load receives an electrical load current via the output terminal and having a current rise speed sensor component connected in series with the power switch and adapted to generate directly a voltage drop corresponding to the current rise speed of the electrical load current flowing from the input terminal of the load control apparatus via the current rise speed sensor component and the power switch to the output terminal and having a driver circuit which is adapted to detect an occurring overcurrent depending on the voltage drop generated by the current rise speed sensor component and depending on a voltage drop along the power switch and which is adapted to switch off said power switch upon detection of an overcurrent within a predefined switch-off period, wherein the driver circuit is adapted to operate independently from a control unit of said load protection apparatus to provide protection against an overcurrent by switching off the power switch if the generated voltage drop plus a voltage drop along the power switch applied to a drive input of the driver circuit as a sum voltage exceeds a configurable threshold voltage;
• said load protection apparatus further comprising an overload protection circuit having a load current sensor component adapted to measure continuously the load current flowing to the output terminal notified to the control unit of the load protection apparatus adapted to determine an overload state and/or a type of the connected electrical load on the basis of the measured load current profile, wherein the type of the electrical load comprises a resistive, inductive or capacitive load type.