ACTA TECHNICA CORVINIENSIS - Bulletin of Engineering

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ACTA TECHNICA CORVINIENSIS – BULLETIN of ENGINEERINGTable 1: Delay time after power-off required todetermine temperature in rated serviceRated power, (kW)/(kVA)Delay time afterpower-off, (s)P ≤ 50 3050 off,rotor and stator winding.Data referring to electrical parameters duringtest (voltage, current, frequency, power factor,etc.) are viewed and recorded through thepower analyzer, and transferred to a PC after thetest.The maximum temperature reached in statorwinding at rated service is determined with thefollowing formula:DETERMINATION OF MAXIMUM SURFACETEMPERATURE FOR LUMINAIRES DESIGNED FORMAIN SUPPLYIn order to determine the maximum surfacetemperature for luminaires the followingapparatus is used: ac power source Kikusui typePCR 1000M, data acquisition system Agilent34970A with thermocouples, laptop Dell LatitudeD830.θ 2 = Δθ + θ awhereΔ θ=R2− RR11× (k + θ1) + θ1− θR 1 – winding resistance value in cold state, in Ω;R 2 – winding resistance value in warm state, inΩ;θ 1 – winding temperature value in cold state,in °C;θ 2 – winding temperature value after heatingtest, in °C;θa – temperature value for the coolingenvironment (ambient);k – reciprocal temperature coefficient forresistance at 0 °C for conductive material; k =235 – for copper; k = 225 for aluminium;T amb – maximum ambient temperature(generally 40°C);The maximum surface temperatureisdetermined as the temperature measured in thehottest point of the motor, with the followingformula:T max = T amb + Δθin this case Δθ represents the highest rise oftemperature (measured in points where thethermocouples were placed).aFigure 5. Test rig to determine maximum surfacetemperature for luminaires designed for main supplyTo determine the maximum surface temperatureof luminaires designed for main supply thefollowing steps should be covered:build-up experimental mounting accordingblock diagram from figure 5;the thermocouples connected to Agilent34970A data acquisition system are placed inpoints considered to be the hottest pointsduring functioning.for tubular fluorescent lamps with mainsupply a diode will be connected in serieswith the lamp, and the luminaire suppliedwith a voltage equal to 110% of rated voltage;the luminaire is powered-on through KikusuiPCR 1000M ac power supply at voltage andfrequency required by standard;in this configuration, the all system willfunction until the maximum temperature innormal functioning is reached (temperaturerising is lower than 2 K/ hour). Thetemperature is monitored by data acquisitionsystem Agilent 34970A with thermocouples;when thermal equilibrium is reached the acpower source output of powered-off, and thedata corresponding to electrical parametersduring test are saved on PC;after approximately 1 minute from power-offthe ac power source output the temperature602010/Fascicule 2/AprilJune /Tome III
ACTA TECHNICA CORVINIENSIS – BULLETIN of ENGINEERINGrecording is stopped and the data is savedon computer;the maximum surface temperature isdetermined with the following formula:t max = t inc + (t amb max - t amb inc )where:t inc – temperature recorded during test (°C) in thehottest spot;t amb max – maximumambient temperature towhich the equipment is designed to work;t amb inc – ambient temperature during test;[4] S. BURIAN, J. IONESCU, M. DARIE, L. MOLDOVAN, etal., Technical apparatus for potentiallyexplosive atmospheres. Group II, 2 nd editionrevised, Europrint Oradea publishing house,2006, ISBN 973-7735-32-3AUTHORS & AFFILIATION1.MARTIN FRIEDMANN,2.LUCIAN MOLDOVAN1INCD-INSEMEX PETROŞANI,ROMANIAIn the end of the test, the temperature shouldnot exceed the temperature specified for thespecific temperature class (80 °C for T6, 95°C forT5, 130°C for T4, 195°C for T3). The temperatureat the rim of the lamp cap and at the solderingpoint of the lamp cap shall not exceed thelimiting temperature.CONCLUSIONSThe purpose of the paper is to underline the newtest that can be done at INCD INSEMEXPetrosani for electrical apparatus with increasedsafety „e” type of protection. These tests are:thermal endurance to heat and cold,determination of surface temperature forluminaries and electric motors; anddetermination of time t E for electrical rotatingmachines. The apparatus needed to run thesetests was in part acquired with funds fromNational Authority for Scientific Research in theNucleu Program.REFERENCES[1] M. FRIEDMANN, L. MOLDOVAN, M. MAGYARI, A.MARTINESCU, Implementation of new evaluationand testing methods for electrical apparatuswith type of protection increased safety inorder to correlate with European legislationand conformation with HG 753/2004, Phase IVReport, 2008, INCD-INSEMEX Petrosani[2] SR EN 60079-0:2007, Electrical apparatus forexplosive gas atmospheres. Part 0: Generalrequirements[3] SR EN 60079-7:2004, Electrical apparatus forexplosive gas atmospheres. Part 7: Increasedsafety “e”2010/Fascicule 2/AprilJune /Tome III 61
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ACTA TECHNICA CORVINIENSIS - Bulletin of Engineering

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