A method for monitoring the operation of a frequency converter (1), which is designed to drive an electric motor (2), wherein the method comprises the following steps: generating phase voltages (u1, u2, u3) for corresponding phase sections (2.1, 2.2, 2.3) of the electric motor (2), ascertaining a voltage rotating field, measuring occurring phase currents (i1, i2, i3), ascertaining a current rotating field depending on the measured phase currents (i1, i2, i3), calculating a phase difference between the voltage rotating field and the current rotating field and/or calculating a frequency difference between the frequency of the voltage rotating field and the frequency of the current rotating field, and determining a fault state when the phase difference exceeds a phase difference threshold value and/or when the frequency difference exceeds a frequency difference threshold value. pa (FIG. 2)

In order to ensure safe operation of a multi-phase system, even a system including a plurality of phases, a number of phase groups is provided, which comprises some of the phases, wherein phase currents of the number of phase groups are merged in a group node to form a group sum current and a group sum current measurement value of the group sum current is captured. The current measurement values belonging to the number of phase groups are summed up to form a group sum and the group sum is compared with the group sum current measurement value to validate the phase currents of the phases in order to ensure safe operation.

The present invention relates to a system for performing phase detection and synchronization in an AMI communication network using a relay communication, and a method thereof. According to an embodiment of the present invention, a system for performing phase detection and synchronization in an AMI communication network using a relay communication includes an AMI server for collecting a ‘reference zero-crossing detection (ZCD) time difference by phase’ of input/output terminals of a main transformer installed in a substation; and a data concentration unit (DCU) comparing the ‘reference ZCD time difference by phase’ transmitted from the AMI server with a ‘ZCD time difference by phase’ collected by itself, and matching the same to have a time difference close to an error range.

The invention involves a multimeter with a meter probe module and phasing probe module capable of wireless communication, proximity measurements, and accurately reading phase degrees. The meter probe module and the phasing probe module can communicate wirelessly, via a wired cable interface, or any combination thereof. The meter probe module and phasing probe module have unique radio frequency serial numbers that allow the probe modules to only communicate with its paired partner probe module while ignoring all other probe modules. The multimeter has a measurement point capable of taking direct contact measurements. The multimeter also has a measurement point capable of taking a voltage measurement without directly contacting the object to be measured. This is accomplished by taking voltage readings from the electric field of the air surrounding said object. The improved multimeter may allow an operator to more safely gather accurate information about an object being measured.

A method for startup of a crystal oscillator (XO) with aid of external clock injection, associated XO and a monitoring circuit therein are provided. The XO includes an XO core circuit, an external oscillator, and an injection switch, where a quality factor of the external oscillator is lower than a quality factor of the XO core circuit. The method includes: utilizing the external oscillator to generate an injected signal; turning on the injection switch to make energy of the injected signal be injected into the XO core circuit, where an amplitude modulation (AM) signal is generated according to combination of the injected signal and an intrinsic oscillation signal from the XO core circuit; and controlling the external oscillator to selectively change an injection frequency of the injected signal according to the AM signal. More particularly, the injection switch is not turned off until the startup process is completed.

A system and method for combining a remote audio source with an animatronically controlled puppet includes the steps of entering an audio file on a user client by a person where the audio file is a statement spoken by the person. The audio file is sent to a secondary client that is remote to the user client. The secondary client has a puppet controlled by animatronics. The audio file is received by an audio circuit board that converts the audio file into movement parameters. The movement parameters are sent to at least one servomechanism mounted in the puppet to actuate the animatronics in synchronicity with the audio file. Movement of the puppet is video recorded to define a video file. The audio and video files are combined to define a final video production viewable by the person.

The present invention relates to a system for performing phase detection and synchronization in an AMI communication network using a relay communication, and a method thereof. According to an embodiment of the present invention, a system for performing phase detection and synchronization in an AMI communication network using a relay communication includes an AMI server for collecting a ‘reference zero-crossing detection (ZCD) time difference by phase’ of input/output terminals of a main transformer installed in a substation; and a data concentration unit (DCU) comparing the ‘reference ZCD time difference by phase’ transmitted from the AMI server with a ‘ZCD time difference by phase’ collected by itself, and matching the same to have a time difference close to an error range.

A method of determining a phase misalignment between a first signal generated from a first signal path and a second signal generated from a second signal path may include obtaining multiple samples of the first signal proximate to when the first signal crosses zero wherein the first signal can be approximated as linear; obtaining multiple samples of the second signal proximate to when the second signal crosses zero wherein the first signal can be approximated as linear; based on the multiple samples of the first signal, approximating a first time at which the first signal crosses zero; based on the multiple samples of the second signal, approximating a second time at which the second signal crosses zero; and determining the phase misalignment between the first signal and the second signal based on a difference between the first time and the second time.

A cooking apparatus includes: a working coil, an inverter including a plurality of switching elements and configured to apply, by operating the plurality of switching elements, a resonant current of a predetermined frequency to the working coil, a phase detector configured to detect a phase difference between the resonant current and a voltage applied to an output terminal of the inverter, and a controller configured to calculate, based on the detected phase difference, a temperature of a target object that is placed above the working coil.

An improved phasor estimation method for M-class phasor measurement units (PMUs) with a low computational burden is described. The method contains three steps: 1) A phasor measurement filter is designed by selecting parameters of Taylor weighted least square method to prioritize dynamic phasor accuracy and a high level of suppression on high-frequency interferences; 2) A finite impulse response lowpass filter is designed by the equal-ripple method is put forward to suppress low-frequency interferences; and 3) Phasor amplitude is corrected under off-nominal conditions.