Disclosed is a measuring bridge arrangement containing: a measuring bridge comprising at least one first half bridge having a first measuring connection and a second half bridge having a second measuring connection; a reference voltage divider having at least one first and a second test connection; a differential amplifier having at least one first and a second amplifier input and at least one amplifier output, a voltage amplification, and having an output voltage working range. In the arrangement, the first amplifier input is wired to a first capacitor and the second amplifier input is wired to a second capacitor, and the amplifier inputs can be selectively connected to the measuring connections or to the test connections.

This invention provides two methods for detecting mechanical or electrical faults in a solenoid valve. In the first method, a force sensor is placed in the valve in such a way as to detect changes in the impact force of the plunger against the solenoid valve body or coil housing (depending upon the direction of movement of the plunger upon application of the electric current/magnetic field). A second method is provided which makes use of an accelerometer placed in such a way as to detect changes in the response of the plunger to the application of the magnetic field.

A connecting device (27) has a first connection input (28), a second connection input (29), and a connection output (30). The two connection inputs (28, 29) are configured for connection to a bus coupling device (20, 21). The connection output is configured for connection to a subscriber (13). The first connection input (28) is connected without switches to the connection output (30) via a first connecting branch (31). The second connection input (29) is connected without switches to the connection output (30) via a second connecting branch (32). The connecting device (27) includes a diagnostic unit (39), which generates a diagnostic signal (D) depending on the first input voltage (U1) and/or the first input current (I1) at the first connection input (28) and/or on the second input voltage (U2) and/or the second input current (I2) at the second connection input (29).

A system and method for a branch current monitoring system employing a 2-Phase Wye, a Single-Phase 3-Wire or a Single-Phase 2-Wire wiring configuration that is configured to identify a phase association and a polarity for a branch circuit current sensor using the phase angle between voltage and current. Also, a system and method for verifying phase association and polarity determinations for branch circuit current sensors that utilizes real and reactive power measurements.

A method and circuit for measuring impedance of a sense-only capacitive sensor operated in loading mode. The method carried out by the circuit includes the steps of: combining a plurality of synchronized output signals; applying low-pass filtering to the summed output signals to generate a sinusoidal test signal; applying the sinusoidal test signal to a sensor signal voltage divider circuit and to a reference voltage divider circuit; determining amplitude and relative phase, with respect to the sinusoidal test signal, of a sensor voltage signal and a reference voltage signal; obtaining a difference voltage signal by subtracting the reference voltage signal from the sensor voltage signal; and feeding the difference voltage signal to a vector demodulator unit for obtaining a real part and an imaginary part of the complex impedance of the capacitive sensor.

A circuit for simulating a capacitance fuel probe, the circuit comprising: an input for receiving an alternating current (AC) excitation signal; an output for outputting an output signal representing a capacitance of the simulated fuel probe; a single reference capacitance; a first amplifier connected to the reference capacitance, the first amplifier being configured to cause a current flow through the reference capacitance; a second, variable gain, amplifier, the second, variable gain amplifier being configured to output an AC signal representing a multiple of the current flow through the reference capacitance, wherein the AC signal output by the second amplifier is used to generate the output signal.

A method and apparatus for testing a duct leak detection system of an aircraft is disclosed. A sensor of the duct leak detection system is selected at an interface of the duct leak detection system. An alternating current is sent through the selected sensor and a resistance of the selected sensor is measured using the alternating current. An indicative signal is generated at the interface when the measured resistance of the selected sensor is outside of a specification of the selected sensor.

A measuring process unit for executing a measuring process of, in correspondence with a plurality of combinations obtained by respectively combining a plurality of connection terminals Tx and a plurality of connection terminals Ty, and in respect of the connection terminals Tx, Ty corresponding to each of the combinations, supplying an AC voltage SA to the connection terminals Ty by means of an AC current source 2 and detecting electric current flowing in the connection terminals Tx by means of an ammeter 3, to thereby acquire currents corresponding to each of the combinations; and a calculating unit for executing a calculating process of, based on the size of the currents detected by the ammeter 3 in the measuring process and on information indicating the currents' phases, calculating capacitance and resistance values corresponding to each of the combinations.

An absence of voltage indicator has an isolation circuit, an FM modulator attached to the isolation circuit, a reference oscillator, and a mixer attached to the reference oscillator and the FM modulator, wherein the output of the mixer is the difference of the two signals. In one embodiment, the FM modulator includes a variable capacitor which varies in response to a voltage in parallel to a fixed capacitor and an inductor in parallel to the capacitors.

The present invention generally relates to proximity sensor monitors and proximity monitor systems incorporating proximity sensor monitors. A proximity sensor monitor measures the impedance or other electrical characteristics of a proximity sensor component to determine the presence of a target. The proximity sensor monitor performs this measurement independently of a separate proximity sensor. The proximity sensor monitor is configured to compensate for differences between the measurement frequency of the proximity sensor monitor and the driving frequency of the proximity sensor.