Abstract- Impacts of harmonics on step-dow presented in this paper. Transformer failure h due to harmonic current causing excessive win rise. Excessive temperature rise of transfo harmonic effect result in higher power l operating mode. An experimental setup is prop for observation of harmonics. This researc transformer losses under nonlinear load with consumption. Moreover, the trends of Total Ha (THD) with nonlinear load are reported. Index Terms—harmonic, transformer losse efficiency NOMENCLATURE R eq Equivalent winding resistance X eq Equivalent leakage reactance R c Core loss resistance X m Magnetizing reactance P LL Total load losses I R RMS sinusoidal AC current P EC-R Total winding eddy current loss w AC current P OSL-R Other stray loss with sinusoidal AC P th Total harmonic losses h Harmonic order F HL Harmonic loss factor for winding e F HL-STR Harmonic loss factor for other stray I. INTRODUCTION Transformers are one of the most impor from generating station to end-user equipm play an important role in minimizing the loss stage by stepping up and stepping down the user equipment, transformer is use to regulate 240V ac to the required output voltage. Common sources of harmonics in indu rectifiers, dc motor drives and electrical balla This work was supported by the Malaysian Ministry and Universiti Teknologi Malaysia through Fundame Scheme (FRGS) vot 4F112. T. L. G. Soh is a full-time Master research student Energy Systems (CEES), Universiti Teknologi gstlg@yahoo.com) D.M. Said is a Senior Lecturer with Centre of Elec (CEES), Faculty of Electrical Engineering, Universiti Johor Bahru, Malaysia. (e-mail: dalila@fke.utm.my) N. Ahmad, K.M. Nor and F. Salim are with Malaysia. Experimental Stu T.L.G. Soh wn transformer are had been reported nding temperature ormer is due to loss than normal posed which allow h focuses on the h different power armonic Distortion es, nonlinear load, with sinusoidal C current ddy current y losses rtant components ment; transformers ses throughout the e voltage. In end- e the voltage from ustrial sector are ast. In this modern y of Higher Education ental Research Grant at Centre of Electrical Malaysia. (e-mail: trical Energy Systems Teknologi Malaysia, Universiti Teknologi era the frequent use of direct curren at end-user equipment, this invo Whenever, there are loads connected the end-user equipment will result Voltage distortion and current disto are the one of the power quality issu Failures in transformers under no with high levels of harmonic curren Nonsinusoidal currents draw by excessive loss and heating [3] in t are usually designed for utilizing at apparent power. Nowadays with the transformer leads to higher losses d which can cause excessive windi temperature rise [4]. Transformer losses can be resolv losses. No-load loss occurs from the core and magnetic hysteresis and arises mainly from the resistance material of the windings [5]. Many works like derating [6]-[10 had been done by researches to loo issue on transformer cause by these is the intentional reduction in load under nonsinusoidal operation [8]. In this paper, harmonic data on st been measured. This work also prov effect on harmonic current toward transformer losses. This paper is organized as follow: in section II, experimental setup discussion in section IV and conclus II. TRANSFORMER L The equivalent circuit of the exper shown in Fig. 1. Transformer losses are obtained b no-load losses and load loss. Eq. udy on the Impact of Ha on Transformer h, D.M. Said, N. Ahmad, K.M. Nor, F. Salim Fig. 1. Single phase transformer equ R eq X eq R c X m nt power supply to the load olved used of rectifiers. d with the power supply in in current distortion [1]. ortion draw by these loads es on transformer. ormal operating condition nts have been reported [2]. y nonlinear load cause transformer. Transformers rated frequency and rated present of nonlinear load, due to harmonic distortion ing losses and abnormal ved into no-load and load e voltage excitation of the eddy currents. Load loss losses in the conducting 0] and modeling [11]-[15] ok into the power quality e nonlinear loads. Derating capacity of a transformer ep-down transformer have vides experimental study of ds single phase dry type : transformer losses study in section III, result and sion in section V. LOSSES STUDY rimental transformer is by calculating the sum of (1) shown the load loss armonics uivalent circuit R s X s 978-1-4673-5074-7/13/$31.00 ©2013 IEEE 2013 IEEE 7th International Power Engineering and Optimization Conference (PEOCO2013), Langkawi, Malaysia. 3-4 June 2013 686