A control device is provided. A first counting unit counts and generates a first output signal. When a counting value of the first counting unit is equal to a first pre-determined value, the first output signal is at a first level. When the counting value of the first counting unit is not equal to the first pre-determined value, the first output signal is at a second level. A second counting unit counts and generates a second output signal. When a counting value of the second counting unit is equal to a second pre-determined value, the second output signal is at the second level. When the counting value of the second counting unit is not equal to the second pre-determined value, the second output signal is at the first level. A determination unit generates a reset signal according to the levels of the first and second output signals.

A control device is provided. A first counting unit counts and generates a first output signal. When a counting value of the first counting unit is equal to a first pre-determined value, the first output signal is at a first level. When the counting value of the first counting unit is not equal to the first pre-determined value, the first output signal is at a second level. A second counting unit counts and generates a second output signal. When a counting value of the second counting unit is equal to a second pre-determined value, the second output signal is at the second level. When the counting value of the second counting unit is not equal to the second pre-determined value, the second output signal is at the first level. A determination unit generates a reset signal according to the levels of the first and second output signals.

A motor controller includes a rectifier for converting AC power supplied from an AC power supply into DC power and outputting the DC power; an AC voltage detector for detecting an AC voltage value of the AC power supply and outputting the AC voltage value as a detection value; a power failure detector for determining that a power failure is occurring, when a state in which the outputted detection value is equal to or lower than a regulation voltage has continued for a regulation time or more; and a power failure detection condition determiner for determining or modifying the regulation time.

A protective redundancy circuit is provided for a power tool having an electric motor. The protective redundant subsystem is comprised of: a motor switch coupled in series with the motor; a motor control module that controls the switching operation of the motor switch; and a protective control module that monitors switching operation of the motor switch and disables the power tool when the switching operation of the motor switch fails. In the context of an AC powered tool, the switching operation of the motor switch is correlated to and synchronized to the waveform of the AC input signal. During each cycle or half cycle, the motor control module introduces a delay period before closing the motor switch and the protective control module determines the operational status of the motor switch by measuring the voltage across the motor switch during the delay period.

A protective redundancy circuit is provided for a power tool having an electric motor. The protective redundant subsystem is comprised of: a motor switch coupled in series with the motor; a motor control module that controls the switching operation of the motor switch; and a protective control module that monitors switching operation of the motor switch and disables the power tool when the switching operation of the motor switch fails. In the context of an AC powered tool, the switching operation of the motor switch is correlated to and synchronized to the waveform of the AC input signal. During each cycle or half cycle, the motor control module introduces a delay period before closing the motor switch and the protective control module determines the operational status of the motor switch by measuring the voltage across the motor switch during the delay period.

Method for detecting a sag in a phase voltage, including the steps of: measuring, upstream of a switching member and at regular intervals, the phase voltage and a phase current flowing through a phase conductor; when the phase voltage falls below a predetermined voltage threshold, opening the switching member; subsequent to opening the switching member, if the phase voltage returns to a normal voltage value defined according to the phase current, detecting a malfunction of the electricity meter, generating a warning message, and keeping the switching member open; subsequent to opening the switching member, if the phase voltage remains below the predetermined voltage threshold, detecting a sag in the phase voltage, generating an alert message, and closing the switching member.

Embodiments of the present disclosure provide an over-voltage protection method, an over-voltage protection device and a display device. When the voltage value of the output signal is greater than the first preset voltage threshold, it is determined whether the voltage value of the output signal meets the preset over-voltage protection condition. If the voltage value of the output signal is detected to meet the preset over-voltage protection condition, the first control signal is output to stop output of the output signal or lower the voltage value of the output signal.

A device for detecting a drop in voltage of an AC supply delivering electrical energy to an energy converter in order to supply electrical equipment, the device being connected to an electrical energy reserve for supplying the energy converter. The device includes a full-wave rectifier for rectifying the AC supply, a comparator that compares a first predetermined voltage with a full-wave rectified voltage, a circuit for charging a capacitor in order to charge the capacitor when the rectified voltage is below the predetermined threshold, a circuit for discharging the capacitor in order to discharge the capacitor when the rectified voltage is above the predetermined threshold, a comparator for comparing the voltage at the terminals of the capacitor with a second predetermined voltage, and a circuit for controlling the reserve of electrical energy.

A device for detecting a drop in voltage of an AC supply delivering electrical energy to an energy converter in order to supply electrical equipment, the device being connected to an electrical energy reserve for supplying the energy converter. The device includes a full-wave rectifier for rectifying the AC supply, a comparator that compares a first predetermined voltage with a full-wave rectified voltage, a circuit for charging a capacitor in order to charge the capacitor when the rectified voltage is below the predetermined threshold, a circuit for discharging the capacitor in order to discharge the capacitor when the rectified voltage is above the predetermined threshold, a comparator for comparing the voltage at the terminals of the capacitor with a second predetermined voltage, and a circuit for controlling the reserve of electrical energy.

A method for operating an electronic switch is described hereinafter. According to one exemplary embodiment, the method (for an electronic switch in the switched on state) comprises detecting whether there is an undervoltage condition at a supply voltage node and providing an undervoltage signal which indicates an undervoltage condition. The method further comprises switching off the electronic switch if the undervoltage signal indicates an undervoltage condition and switching (back) on the electronic switch if the undervoltage signal no longer indicates an undervoltage condition. If the undervoltage signal indicates an undervoltage condition during a switch-on process of the electronic switch, the electronic switch is switched off again and switching back on is prevented for a defined period of time, irrespective of the undervoltage signal. Moreover, a corresponding circuit is described.