SIMULASI PELIMPAHAN BEBAN PMT OUTGOING PWI 06 SAAT TERJADI OVERLOAD SHEDDING PADA TRAFO INCOMING 03 GARDU INDUK PURWODADI DENGAN MONITORING VT SCADA BERBASIS ARDUINO MEGA 2560

Reza Rizkifadhla, Heru Winarno, in this article explains that overload shedding in incoming transformer occurs due to an increase in load current that exceeds the capacity of the transformer. If overload shedding is not handled, it will cause damage to the transformer, and even cause incoming trip feeders and a very wide blackout effect. Relay overload shedding mounted on incoming feeders works to anticipate overload shedding by deliberately releasing outgoing feeders gradually to reduce the load. This study aims to provide a simulation of the conditions of incoming feeders during normal times, during overload shedding and handling of outgoing feeders deliberately released by carrying out load maneuvers to other feeders with different incoming transformers. Maneuvers are carried out to maintain the reliability of the continuity of electricity distribution. In this study one simulation tool was designed. The design of this tool uses a relay and Arduino Mega 2560 as a control center. Arduino Mega 2560 reads the current using the ZMCT 103C sensor. The simulation is based on the overload shedding event that has occurred in Purwodadi Substation. As for controlling switching equipment and monitoring current and voltage is done using HMI with VT Scada software. In the experiment, 3 incoming normal currents were 2.2 A with a load of 5 12 VAC 5W lamps. Simulated maneuvering error, the load on incoming 3 increased to 2.60 A. This situation is considered to have reached the condition of overload shedding, relay PMT C trip to reduce the load. Incoming 3 returns back to normal, namely 1.68 A. Loads on PMT C that are extinguished are maneuvered to PMT E or PMT F which have different incoming.

Dependence of aging on inhomogeneities in InGaN/AlGaN/GaN light-emitting diodes

Changes of properties of green LEDs based on InxGa1−xN/AlyGa1−y/GaN heterostructures were studied during 150÷200 hours at currents J = 30÷ 80 MA The radiation intensity at low currents (0.1÷1 mA) is quite sensitive to such an aging, it falls down 10÷100 times. Quantum efficiency and spectral parameters at normal currents (J ≈ 10 mA) change non-monotonically during aging, some degradation is observed after 168 hours. The degradation is observed also after a short (< 1 min) period of reverse current. These phenomena are discussed in terms of under threshold defect’s formation and their migration in the space charge region of p-n-heterojunction. Potential fluctuations in the space charge region are quite sensitive to this process.

Dependence of Aging on Inhomogeneities in InGaN/AlGaN/GaN Light-Emitting Diodes

Changes of properties of green LEDs based on InxGa1-xN/AlyGa1-y/GaN heterostructures were studied during 150÷200 hours at currents J = 30÷80 mA. The radiation intensity at low currents (0.1÷1 mA) is quite sensitive to such an aging, it falls down 10÷100 times. Quantum efficiency and spectral parameters at normal currents (J ≈ 10 mA) change non-monotonically during aging, some degradation is observed after 168 hours. The degradation is observed also after a short (< 1 min) period of reverse current. These phenomena are discussed in terms of under threshold defect's formation and their migration in the space charge region of p-n-heterojunction. Potential fluctuations in the space charge region are quite sensitive to this process.

A microampere radiotelemetry transmitter for measurement of temperature from unrestrained subjects

A miniature radiotelemetry transmitter is described suitable for chronic or acute monitoring of temperatures from animal or human subjects. The transmitters can be easily constructed with little or no electronics background from discrete components readily available from any electronics supplier. Transmitters weighed from 2.5–20 g, had volumes of 0.8–3.5 ml, had normal currents of 50–120 muA with potential transmitter lives of 35 h to greater than 1 yr, and transmission ranges of 10–30 m. Transmitters could be implanted, swallowed, or connected to chronically or acutely attached temperature probes. The design of the telemetry system allows for reception on any commercial FM receiver. Depending on mode of decoding the temperature data transmitter signal can be accurate to measure changes of from 0.15 to 0.015 degrees C. Thus with a minimum of expense and little electronics background a temperature-dependent transmitter system can be constructed for monitoring temperatures from unrestrained subjects.