To enable early detection of AC insulation faults, or to permit easier, faster and more accurate measurement of small currents in inverters, a current measuring circuit for a converter is provided. The current measuring circuit has a positive supply rail, a negative supply rail, a reference potential rail and a current measuring device that contains a Y-capacitor and a current sensor connected in series therewith. The load current can be decoupled from the measurement current through the at least one Y-capacitor, so that at high load currents even small fault currents can be acquired reliably with the current sensor.

To enable early detection of AC insulation faults, or to permit easier, faster and more accurate measurement of small currents in inverters, a current measuring circuit for a converter is provided. The current measuring circuit has a positive supply rail, a negative supply rail, a reference potential rail and a current measuring device that contains a Y-capacitor and a current sensor connected in series therewith. The load current can be decoupled from the measurement current through the at least one Y-capacitor, so that at high load currents even small fault currents can be acquired reliably with the current sensor.

A controller transmits a message on a channel at a time the channel is predicted to be unoccupied according to a time ordered series of symbols. Each of the symbols represents a group of discrete time durations during which the channel has been occupied by a periodic signal and a corresponding feature of the periodic signal during the discrete time durations.

A controller transmits a message on a channel at a time the channel is predicted to be unoccupied according to a time ordered series of symbols. Each of the symbols represents a group of discrete time durations during which the channel has been occupied by a periodic signal and a corresponding feature of the periodic signal during the discrete time durations.

An apparatus and a method for non-destructive inspection of quality of an electrostatic chuck are disclosed. The apparatus includes a measurement unit for measuring a first capacitance of a dielectric layer of the electrostatic chuck and for measuring a second capacitance of an electrode installed in the dielectric layer; and a control unit configured to evaluate quality of the electrode, based on the first capacitance and the second capacitance.

An apparatus and a method for non-destructive inspection of quality of an electrostatic chuck are disclosed. The apparatus includes a measurement unit for measuring a first capacitance of a dielectric layer of the electrostatic chuck and for measuring a second capacitance of an electrode installed in the dielectric layer; and a control unit configured to evaluate quality of the electrode, based on the first capacitance and the second capacitance.

The present application provides a stack module fault monitoring system, comprising an insulation resistance tester; a stack module, which consists of m groups of stack strings; m electronic switch groups, wherein each electronic switch group comprises a first switch and a second switch; one end of the first switch is connected with positive electrodes of one group of stack strings, and the other end of the first switch is connected with a positive electrode end of the insulation resistance tester; one end of the second switch is connected with negative electrodes of the group of stack strings, and the other end of the second switch is connected with a negative electrode end of the insulation resistance tester; a control end of a switch in the electronic switch group is connected with a controller, and the switch in the electronic switch group is controlled to be on and off by the controller; the insulation resistance tester tests the insulation resistance of each group of stack strings in sequence and sends the insulation resistance to the controller; the controller determines whether the group of stack strings has then insulation fault or not according to the insulation resistance, so as to realize online monitoring on whether each group of stack strings has the insulation fault or not, and quickly position the stack string with the insulation fault in the stack module.

The present application provides a stack module fault monitoring system, comprising an insulation resistance tester; a stack module, which consists of m groups of stack strings; m electronic switch groups, wherein each electronic switch group comprises a first switch and a second switch; one end of the first switch is connected with positive electrodes of one group of stack strings, and the other end of the first switch is connected with a positive electrode end of the insulation resistance tester; one end of the second switch is connected with negative electrodes of the group of stack strings, and the other end of the second switch is connected with a negative electrode end of the insulation resistance tester; a control end of a switch in the electronic switch group is connected with a controller, and the switch in the electronic switch group is controlled to be on and off by the controller; the insulation resistance tester tests the insulation resistance of each group of stack strings in sequence and sends the insulation resistance to the controller; the controller determines whether the group of stack strings has then insulation fault or not according to the insulation resistance, so as to realize online monitoring on whether each group of stack strings has the insulation fault or not, and quickly position the stack string with the insulation fault in the stack module.

The present disclosure relates in a first aspect to a method of detecting leakage current from a DC bias voltage circuit of an integrated circuit for a capacitive microelectro mechanical systems (MEMS) transducer. A test signal with a predetermined frequency and level is superimposed on a first DC bias voltage generated by the DC bias voltage circuit.

The present disclosure relates in a first aspect to a method of detecting leakage current from a DC bias voltage circuit of an integrated circuit for a capacitive microelectro mechanical systems (MEMS) transducer. A test signal with a predetermined frequency and level is superimposed on a first DC bias voltage generated by the DC bias voltage circuit.