What is the power factor on a 480-volt, 60-horsepower, 3-phase motor with an efficiency of 85% when the full load current is 70 amperes?<\/p>\n\n\n\n
The Correct answer and Explanation is:<\/mark><\/strong><\/p>\n\n\n\n To calculate the power factor of a 480-volt, 60-horsepower (HP), 3-phase motor with an efficiency of 85% and a full load current of 70 amperes, we need to break down the problem into steps. The power factor (PF) is the ratio of real power (P) to apparent power (S), expressed as:<\/p>\n\n\n\n [ \\text{Power Factor} (PF) = \\frac{\\text{Real Power} (P)}{\\text{Apparent Power} (S)} ]<\/p>\n\n\n\n First, convert the motor\u2019s power rating from horsepower to watts. The formula to convert HP to watts is:<\/p>\n\n\n\n [ \\text{Power (Watts)} = \\text{Horsepower} \\times 746 ]<\/p>\n\n\n\n For a 60 HP motor:<\/p>\n\n\n\n [ \\text{Power (Watts)} = 60 \\times 746 = 44,760 \\, \\text{Watts} ]<\/p>\n\n\n\n Efficiency represents how much of the input power is converted into useful output power. The motor\u2019s efficiency is 85%, so the input power can be calculated as:<\/p>\n\n\n\n [ \\text{Input Power} = \\frac{\\text{Output Power}}{\\text{Efficiency}} ]<\/p>\n\n\n\n For this motor:<\/p>\n\n\n\n [ \\text{Input Power} = \\frac{44,760 \\, \\text{Watts}}{0.85} = 52,659 \\, \\text{Watts} ]<\/p>\n\n\n\n The apparent power is calculated using the formula for 3-phase systems:<\/p>\n\n\n\n [ S = \\sqrt{3} \\times V \\times I ]<\/p>\n\n\n\n Where:<\/p>\n\n\n\n Thus:<\/p>\n\n\n\n [ S = 1.732 \\times 480 \\times 70 = 58,185 \\, \\text{Volt-Amperes (VA)} ]<\/p>\n\n\n\n Now, we calculate the power factor by dividing the real power (input power) by the apparent power:<\/p>\n\n\n\n [ PF = \\frac{52,659}{58,185} \\approx 0.905 ]<\/p>\n\n\n\n The power factor of this motor is approximately 0.905<\/strong>. This means that about 90.5% of the apparent power is being effectively used for productive work, while the rest is reactive power. A power factor close to 1 is ideal for efficient electrical systems, and this motor has a relatively good power factor.<\/p>\n","protected":false},"excerpt":{"rendered":" What is the power factor on a 480-volt, 60-horsepower, 3-phase motor with an efficiency of 85% when the full load current is 70 amperes? The Correct answer and Explanation is: To calculate the power factor of a 480-volt, 60-horsepower (HP), 3-phase motor with an efficiency of 85% and a full load current of 70 amperes, […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"categories":[25],"tags":[],"class_list":["post-143631","post","type-post","status-publish","format-standard","hentry","category-exams-certification"],"_links":{"self":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/143631","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/comments?post=143631"}],"version-history":[{"count":0,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/posts\/143631\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/media?parent=143631"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/categories?post=143631"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.learnexams.com\/blog\/wp-json\/wp\/v2\/tags?post=143631"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}Step 1: Convert Horsepower to Watts<\/h3>\n\n\n\n
Step 2: Account for Efficiency<\/h3>\n\n\n\n
Step 3: Calculate Apparent Power (S)<\/h3>\n\n\n\n
\n
Step 4: Calculate the Power Factor (PF)<\/h3>\n\n\n\n
Conclusion<\/h3>\n\n\n\n