Abstract: A perimeter fence comprises at least one substantially horizontal base portion and at least one corresponding barrier portion, which is removably secured to the respective base portion, comprising a pair of substantially vertical posts and a panel supported therebetween. The fence limits access to a designated area and can be used, for example, for crowd control at concerts and other outdoor events, protest/demonstration crowd management and facility/infrastructure perimeter protection. The fence utilizes a modular design and an improved fastening and storage system; and thus can be readily assembled for mobile use and disassembled for storage and transport. Metal expanded wire mesh or solid panels are provided to maximize security and limit access. The fence is provided in various dimensions to reduce scalability and thus further limit access. A plurality of adjacent panels can be employed to extend the fence as necessary about the designated area based on the particular application.

Abstract: An apparatus and method for characterizing an alternating current power line which uses a library of waveforms and associated spectra of digitally sampled alternating current power system voltage or current waveforms. The library of waveforms is built as new waveforms are measured from the alternating current power line. A measured waveform that is not found in the library will be converted to frequency-domain representation, using a Discrete Fourier Transform, that will then be stored in the library. When the library becomes full, the frequency domain representation of the new waveform will be stored in place of the least used waveform currently stored in the library.

Abstract: A stand-alone electronic measuring instrument for measuring AC (alternate current) power parameters on a utility distribution system wherein the measurement results are communicated telephonically to a facsimile device. Well-known techniques are used to acquire and accumulate analog signals representative of voltages and currents on an AC power system and digital signals. If the signals exceed a programmed threshold, or if an interval of time elapses, or if some other triggering even occurs, the instrument prepares a bit-mapped digital report on its accumulated input signals which may contain text, graphics, or both. The instrument then employs well-known techniques to telephonically transmit this report directly to a facsimile receiver without employing an intervening computer system.

Abstract: An instrument for measuring voltage harmonics and current harmonics on AC (alternating current) power systems. The instrument includes the ability to determine when threshold limits have been exceeded for harmonics. The instrument also includes timing thresholds whose inputs are activated when the harmonic thresholds are exceeded. A single harmonic threshold is applied to measurements from multiple phases on poly-phase systems by comparing the square rot of the sum of the squares of measurements from each phase to the harmonic threshold. Three indicators show when voltage harmonic limits are exceeded, current harmonics limits are exceeded, or both voltage and current harmonic limits are exceeded simultaneously.

Abstract: An instrument for measuring voltage harmonics and current harmonics on AC (alternating current) power systems The instrument includes the ability to determine when threshold limits have been exceeded for harmonics. The instrument also includes timing thresholds whose inputs are activated when the harmonic thresholds are exceeded A single harmonic threshold is applied to measurements from multiple phases on poly-phase systems by comparing the square root of the sum of the squares of measurements from each phase to the harmonic threshold. Three indicators show when voltage harmonic limits are exceeded, current harmonics limits are exceeded, or both voltage and current harmonic limits are exceeded simultaneously.

Abstract: An instrument for measuring voltage harmonics and current harmonics on AC (alternating current) power systems. The instrument includes the ability to determine when threshold limits have been exceeded for harmonics. The instrument also includes timing thresholds whose inputs are activated when the harmonic thresholds are exceeded. A single harmonic threshold is applied to measurements from multiple phases on poly-phase systems by comparing the square root of the sum of the squares of measurements from each phase to the harmonic threshold. Three indicators show when voltage harmonic limits are exceeded, current harmonics limits are exceeded, or both voltage and current harmonic limits are exceeded simultaneously.

Abstract: A locking apparatus is coupled to and incorporated within an electronic instrument to ensure that the instrument operates within a predetermined set of performance parameters. The instrument's operating characteristics will be tested and measured by an external, automatic test system as is typical in the manufacture of many electronic instruments. The locking device will prevent the ordinary operation of the instrument until the instrument has successfully passed the tests administered by the automatic test system. Upon successful completion of the tests, the test system will communicate a signal to the locking device. Upon receipt of the control signal, the locking device will "unlock" the instrument allowing normal operation. In order to ensure that routine calibration takes place, the locking device can be instructed to periodically disable normal operation of the instrument until another performance test is administered by an automatic test system.