• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.625-627
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• 2002

High precision voltages. currents. power factor and electrical power measurements wide range of frequency can be achieved by using the thermo-elements (thermal converters). This paper describes the development wattmeter. based on a thermal principle. The instrument has been performed measurement in the range of currents from 0 to 50 A, voltages up to 600 V, power factor 0.5. 1 and frequencies from 45 Hz to 3 kHz. The thermal converters with two heater are used in the functional element of the wattmeter.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.10
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• pp.568-572
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• 2002

High precision voltages, currents, and electrical power measurements in wide range of frequency can be achieved by using the thermo-elements(thermal converters). This paper describes a development wattmeter, based on a thermal principle. The instrument has been performed measurement in the range of currents from 0 to 50 A, voltages up to 480 V, power factor 0.5 (lag, lead), 1 and frequencies from 60 Hz to 3 KHz. It is intended to be used by electric utilities, standard laboratories, testing laboratories, and applications where high measurement accuracy are attractive consideration.

• 전기의세계
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• v.30 no.11
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• pp.734-746
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• 1981

This paper suggests on-load torque measurement for 3 phase induction motors by input -voltage and current utilizing symmetric coordinate analysis technique on the basis of the induction motor equivalent circuit. In this paper, two cases are treated with, i.e, one is the case where the motors' exciting current and primary leakage impedance voltage drop are compensated automatically, adopting the ideal wattmeter whose current coil impedance and voltage coil impedance are 0 and .inf. respectively, and the other is the case where non-ideal wattmeter is adopted and the compensation above is made by computation. As a result of the case study, following conclusions are obtained. 1) By proper combination of the error propagation law and the limit of power consumption, the desirable overall measurement error of the apparatus can be obtained on the basis of the inherent errors of CT and PT. 2) The measurement error is larger in current simulation circuit than in voltage simulation circuit. 3) Between the two cases, the latter is more advantageous than the former from the viewpoint of feasibility and the measurement error. 4) As the attachment of Ammeter in the current simulation circuit influences the measurement error considerably, its internal impedance should be large considerably. 5) The larger the consumption power of the apparatus is, the easier the feasibility is.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.10a
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• pp.37-40
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• 2003

This paper presents calculated and measured AC losses of the HTS pancake coil. Magnetic field in the HTS coil under operating conditions was calculated by FEM. Results of measured ac loss in 4-stacked short sample were used in the AC loss calculation. Various methods, such as, electric method, calorimetric method, wattmeter method, were used to measure the AC loss.

• Journal of Advanced Marine Engineering and Technology
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• v.11 no.4
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• pp.33-40
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• 1987

Arc power is consumed energy per unit time between welding electrodes. The relations between consumed energy and electrode distance, current, voltage are nonlinear characteristics. Therefore commercial A.C. wattmeter cannot be used for measurement of the arc power. Most of arc energy measuring systems are developed for relay contact arc measurement. Relaly arc requires integrated instantaneous power because relay arc finishes in a short instant. But most of welding powers are continually consumed powers, therefore instantaneous power must be continually indicated in the form of averagy value. The author propose a new measurement method of power in which the current and voltage of welding electrode is multiplied and the resultant signal is passed to low pass filter in order to remove higher order frequency components. After integrating, the signal is devided by the integral interval and the results are stored in a computer memory.

• Journal of Korea Multimedia Society
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• v.20 no.7
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• pp.1046-1053
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• 2017

We propose a design method of high accuracy power measuring device and the method of securing the reliability of the measured data. As a design method for the development of the high accuracy power measuring device, the circuit was made by reflecting the high accuracy power measuring ICs and the CT (Current Transformer). To ensure the reliability of the power meter, we requested to the watt-hour meter certified testing organization to measure the error rate, and the error rate of active power based on the "Wattmeter Technical Standard(Revision notify 2014-283)" was measure, and the error rate was confirmed to be less than 0.1%.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.51 no.11
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• pp.622-627
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• 2002

The power comparison techniques have implemented power measurements, in which a power comparator is used to balance ac against a dc power obtained from known values. The developed power standard system using the comparison techniques consists of dc sources, ac source, control switches, resistive voltage dividers, resistive shunts and a power comparator. The total uncertainty of the power standard system was proved by analysis of the component instruments. Its expanded(k=2) uncertainty is evaluated to be less than 30 uW/VA at unit power factor and 42 uW/VA at power factor 0.5

• Journal of Korea Multimedia Society
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• v.22 no.3
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• pp.366-373
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• 2019

The development of monitoring and analysis systems to increase productivity while saving energy is needed as a method to reduce huge amount of energy consumed in the process of producing large forged products. In this paper, we propose a system to monitor and analyze energy usage in real-time collected from gas-meter, wattmeter, and thermometer based on IoT installed in forging factories. The system consists of a data collection server for collecting and processing data from IoT- based platform and existing SCADA equipment and ERP/MES system in forging factories, and an application server for providing services to users. To develop the system, the overall system structure is logically diagrammed, and the databases configuration and implementation modules to efficiently store and manage data are presented. In the future, the system will be utilized to reduce energy consumption by analyzing energy usage pattern and optimizing process works with real-time energy usage and production process data for each facility.

• KIEAE Journal
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• v.16 no.6
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• pp.109-114
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• 2016

Purpose: The underground air is the warm air discharged from the porous volcano bedrock 30-50m underground in Jeju, including excessive humidity. The temperature of the underground air is $15-20^{\circ}C$ throughout the year. In Jeju, the underground air was used for heating greenhouses by supplying into greenhouses directly. This heating method by supplying the underground air into greenhouses directly had several problems. The study was conducted to develop the heat pump system using underground air as heat source for resolving excessive humidity problem of the underground air, adopting the underground air as a farm supporting project by Ministry of Agriculture, Food and Rural Affairs(MAFRA) and saving heating cost for agricultural facilities. Method: 35kW scale(10 RT) heat pump system using underground air installed in a greenhouse of area $330m^2$ in Jeju-Special Self-Governing Province Agricultural Research & Extension Services, Seogwipo-si, Jeju. The inlet and outlet water temperature of the condenser, the evaporator and the thermal storage tank and the underground air temperature and the air temperature in the greenhouse were measured by T type thermocouples. The data were collected and saved in a data logger(MV200, Yokogawa, Japan). Flow rates of water flowing in the condenser, the evaporator and the thermal storage tank were measured by an ultrasonic flow meter(PT868, Panametrics, Norway). The total electric power that consumed by the system was measured by a wattmeter(CW240, Yokogawa, Japan). Heating COP, rejection heat of condenser, extraction heat of evaporator and heating cost were analyzed. Result: The underground air in Jeju was adopted as a farm supporting project by Ministry of Agriculture, Food and Rural Affairs(MAFRA) in 2010. From 2011, the heat pump systems using underground air as a heat source were installed in 12 farms(16.3ha) in Jeju.

• Journal of Internet Computing and Services
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• v.19 no.1
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• pp.87-95
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• 2018

Due to global warming and increased energy costs around the world, interests of energy saving and efficiency have been increased. In particular, forging factories need methods to save energy and increase productivity because of needing amounts of energy uses. To solve the problem, we propose a system, which includes collection, monitoring, and analysis process, to monitor energy uses each facility in realtime based on the IoT devices. This system insists of worksheets management, facility/energy management, realtime monitoring, history search, data analysis through connecting with existed ERP/MES Systems in manufacturing factories. The energy monitoring process is to present used energy collected from IoT devices connected with installed gasmeter and wattmeter each facility. This system provide the change of energy uses, usage fee, energy conversion, and green gas information in realtime on Web and mobile devices. This system will be enhanced with energy saving technology by analyzing constructed big data of energy uses. We can also propose a method to increase productivity by integrating this system with functions of digitalized worksheets and optimized models for production process.