Feasibility of zero phase current detection by sensing current at each of the three phases in power distribution networks

Takajo

1998

Self Cite

The HP3458A has been well known as a high precision-type digital multimeter ͑DMM͒. However, when trying to identify any infinitesimally small ac signals as effective values, the existence of large residual noise appearing at the output reading when input signals to be measured are zero impedes the achievement of high precision to its full capability. This article shows that the greater part of the residual noise is produced as electronic noise from within the DMM and presents a trial of achieving high precision measurement by introducing a concept of noise decoupling. An equivalent zero noise state is searched for on one of the decoupled components by attaching an additional circuit in parallel and/or antiparallel to the input terminals and is found to be attainable with respect to the attached circuit. Consequently, possibilities of providing the full resolution to its capability and serving high precision measurement are discussed.

Section: A Question To Conventional Treatmentmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Precise and accurate measurement of ac signals by high precision-type digital multimeter HP3458A

Ueda

Takajo

1998

Self Cite

“…A current sensor which was developed based on the magnetic sensor gives full scope to the performance in detection of a faint leak current. 2 In relation to it, a magnetic core noise measurement system has also been developed for inquiring closely into the core qualified for their sensors. 3 All of them require accurate and precise extraction of the instantaneous value of a small signal ͑less than V͒.…”

Section: Introductionmentioning

confidence: 99%

On derivation of a thermal transfer model of a thermostat housing a heat source with several watts

Yoshihiro

Sonoda

et al. 1997

Self Cite

Temperature stabilized effusion cell evaporation source for thin film deposition and molecular-beam epitaxy Rev.A very precisely regulated compact thermostat for small-angle neutron scattering Rev.This article presents a trial for deriving a thermal transfer model of a thermostat housing a heat source generating several watts and achieving high temperature stabilization. It is intended for investigating the open-loop linearity of operational amplifiers labeled as high precision or low noise and their noise characteristics. This thermostat is built up with a double-jacket constructed with a copper plate of 10 mm thickness and an approach of deriving a lumped parameter model to each jacket on the temperature control is presented. The temperature stability of the order of 3 ϫ 10 Ϫ5°C per 1°C temperature change in the air outside in 1 h is realized in the inner jacket. The linearity is measurable and it is clarified that amplifiers are classified into three groups.

Noise investigation of a high precision digital multimeter model HP3457A or HP3458A for microvolt level dc voltage measurements

Ueda

Takajo

1999

A high temperature apparatus for measurement of the Seebeck coefficient Rev. Sci. Instrum. 82, 063905 (2011);A new correlation method for high sensitivity current noise measurements Rev.This article examines noise characteristics of a high precision digital multimeter HP3457A or HP3458A by presenting a conceptual but useful model for the generation of zero voltage error under short-circuited input terminals. Two setting states, auto-zero on ͑AZ-ON͒ and off ͑AZ-OFF͒ are tested and one important conclusion derived is that the state of AZ-OFF has a more extensive potential of performing to the full specifications for measurements of V level dc voltage than that of AZ-ON.