The present invention relates to a method and monitoring device, for monitoring N number of transformer bushings operating in substantially the same environment. N being any number more than 1. The method comprises estimating an absolute value for the capacitances of each of the bushings, the absolute values for the capacitances being denoted C.sub.x, and estimating an absolute value for the loss factor or the power factor of each of the bushings, the absolute values for the loss factors or the power factors being denoted F.sub.x. X is a number representing which bushing the value is associated to and X larger than 1. The method further comprises calculating -values for all C values and -values for all F values, according to:
C.sub.X=C.sub.XC.sub.X+1, for all values up to, and including, C.sub.N1,
C.sub.N=C.sub.NC.sub.1, for C.sub.N,
F.sub.X=F.sub.XF.sub.X+1, for all values up to, and including, F.sub.N1,
F.sub.N=F.sub.NF.sub.1, for F.sub.N,
and determining whether the -values are within predefined ranges.

A pest sensor and a detector for use in a pest sensing system are described. The pest sensor comprises a processor configured to: receive a first signal indicative of a first impedance across a first sensing circuit; receive a second signal indicative of a second impedance across a second sensing circuit; and in response to detecting that one of the first or second signals differs from the other by more than a predefined difference threshold, output an indication of pest activity.

A system for monitoring transformer bushings sensors, wherein first and second bushing sensors are connected to a common first phase of a high voltage source, and the third and fourth bushing sensors are connected to a common second phase of the high voltage source. A first time series is generated from the first and second bushing sensors during a predetermined time interval. A second time series, is generated from the third and fourth bushing sensors during the predetermined time interval. A correlation model for the first and second time series for determining a difference between a measured signal and an estimated signal, and generating a signal indicative of a bushing problem the difference is larger than a threshold.

The invention generates a model of the composition of the cable segments in a network. Different cable compositions have different loss distributions. Each cable segment is given a starting cable composition (based on cable records if available), and thus can be represented as a loss distribution. The loss for each circuit can be measured (by measuring H log), and thus can also be represented as a loss distribution. Updates are made to the loss distribution for each segment so that the loss distributions that make up each circuit is consistent with that of the (measured) loss distribution for that circuit. These updates are preferably performed as Bayesian updates of each cable segment (loss distribution) using Gibbs sampling (i.e. the other cable segment loss probabilities are fixed whilst the probability for the segment under consideration is updated).

A test apparatus includes a host compliance printed circuit board having a first circuit plane and a second circuit plane separated by at least one dielectric layer. A first row of surface mount pads are disposed on the first circuit plane. The first row of surface mount pads includes a first pad and a second pad. A second and third row of surface mount pads are disposed on the first circuit plane. A first and second differential pair of circuit lines is disposed on the first circuit plane. The first differential circuit line has one end coupled to the first pad. The second differential circuit line has one end coupled to the second pad. The first and second differential pair of circuit lines extend from the first and second pads and between the second and third rows of surface mount pads.

According to one embodiment, a communication device is described comprising an antenna, a signal path for supplying a signal to the antenna, two directional couplers arranged within the signal path, wherein each directional coupler is coupled to an adjustable impedance defining the characteristic impedance of the directional coupler, a controller configured to set, for each of a plurality of impedances, the adjustable impedances of the directional couplers to the impedance, a return loss measurement circuit configured to determine, for each of the plurality of impedances, a return loss of the signal path when the adjustable impedances of the directional couplers are set to the impedance and a load impedance determination circuit configured to determine a load impedance of the signal path based on the determined return losses.

A system for monitoring transformer bushings sensors, wherein first and second bushing sensors are connected to a common first phase of a high voltage source, and the third and fourth bushing sensors are connected to a common second phase of the high voltage source. A first time series is generated from the first and second bushing sensors during a predetermined time interval. A second time series, is generated from the third and fourth bushing sensors during the predetermined time interval. A correlation model for the first and second time series for determining a difference between a measured signal and an estimated signal, and generating a signal indicative of a bushing problem the difference is larger than a threshold.

A method and system of a method of measuring complex dielectric constant and permeability includes directing two polarizations onto a material under test and measuring one or more values of reflection coefficients. Further, the method includes integrating a p-wave reflection coefficient and a s-wave reflection coefficient and calculating, based on the measured one or more values of the reflection coefficients in association with a Brewster's angle, one or more of a complex dielectric constant and permeability.

Test measurements on a utility power device by a switch matrix apparatus and a common voltage source as separate devices is performed. Through the switch matrix apparatus, the common voltage source selectively sends a first high voltage signal via a first lead to a first terminal of the utility power device, measures a first corresponding signal returned via a second lead of the switch matrix apparatus from a second terminal of the utility power device. While the first lead and the second lead of the switch matrix apparatus remain electrically coupled to the first and the second terminal of the utility power device, a second high voltage signal is selectively sent via the second lead to the second terminal of the utility power device, and a second corresponding signal returned from the first terminal of the utility power device via the first lead of the switch matrix apparatus is measured.

Test measurements on a utility power device by a switch matrix apparatus and a common voltage source as separate devices is performed. Through the switch matrix apparatus, the common voltage source selectively sends a first high voltage signal via a first lead to a first terminal of the utility power device, measures a first corresponding signal returned via a second lead of the switch matrix apparatus from a second terminal of the utility power device. While the first lead and the second lead of the switch matrix apparatus remain electrically coupled to the first and the second terminal of the utility power device, a second high voltage signal is selectively sent via the second lead to the second terminal of the utility power device, and a second corresponding signal returned from the first terminal of the utility power device via the first lead of the switch matrix apparatus is measured.