Indonesian Journal of Electrical Engineering and Computer Science Vol. 17, No. 2, February 2020, pp. 759~766 ISSN: 2502-4752, DOI: 10.11591/ijeecs.v17.i2.pp759-766  759 Journal homepage: http://ijeecs.iaescore.com Examination on the Physical Properties of Untreated Kenaf Insulation Paper at Different Beating Degrees Muhammad Umair 1 , Norhafiz Azis 2 , Rasmina Halis 3 , Jasronita Jasni 4 1,2,4 Advanced Lightning and Power Energy Research (ALPER), Centre for Electromagnetic and Lightning Protection Research (CELP), Faculty of Engineering, Universiti Putra Malaysia, Malaysia 2 Institute of Advanced Technology (ITMA), Universiti Putra Malaysia, Malaysia 3 Department of Forest Production, Faculty of Forestry, University Putra Malaysia, Malaysia Article Info ABSTRACT Article history: Received May 1, 2019 Revised Jul 2, 2019 Accepted Jul 16, 2019 This paper examines the physico-mechanical properties of untreated kenaf based insulation paper with consideration on different beating degrees. Kenaf bast fibers were first processed through soda pulping process. Different beating degrees were subjected to the processed pulps. Physical parameters of the paper were measured for each of the beating degrees. It is found that as the beating revolution increases, the kenaf based insulation paper’s density, tensile index and burst index increase while thickness and tear index decrease. Keywords: insulation paper kenaf fibers physical properties Copyright © 2020 Institute of Advanced Engineering and Science. All rights reserved. Corresponding Author: Muhammad Umair, Department of Electrical Engineering, 43400 Serdang, Malaysia. Email: umair9926@gmail.com 1. INTRODUCTION Majority of transformers in the power system networks use wood based papers as one of the main insulation systems. Wood based insulation papers are reliable, cost effective and comply with the thermal, mechanical and electrical requirements for application in transformers [1]. Other alternative sources for papermaking can be from non-wood plants such as wheat straws, sugarcane, bamboo, hemp, bagasse, cotton and jute [2]. Non-wood plants have different charateristics of fibers. Cellulose extracted from non-wood fibers can be used to produce papers with different properties [2-4]. Kenaf is a non-wood plant, recognized as the source for producing papers and paperboard [6]. Kenaf fibers have been used in different types of other applications such as building/packaging materials, papermaking and composite wood [4-7]. Core and bast fibers are the main components in kenaf plants. The lengh of core fibers are shorter than the bast fibers [4, 8]. The papers used in transformers normally have long fibers which contribute to the high mechanical strength which is essential to withstand any physical movements due to the operation [9]. Generally, the length, chemical composition and cell wall thickness of fibers determine the physical properties of papers [10]. Bast fibers lengths of kenaf plant can be between 2.32 mm and 2.62 mm which depend on the age, location and species [3, 4]. One study shows that the mechanical behaviour of kenaf bast fibers is quite close to wood fibres. Furthermore, it is shown that the tear resistance of kenaf bast fibers can be higher than wood fibers. Core fibers are short and contains 60% - 65% of the plant by weight. The length of core fibers can be in between 0.5 mm and 0.7 mm [4]. The physical properties of kenaf based paper can be further improved