Ghi ch\u00fa: T\u00e0i li\u1ec7u tr\u00edch d\u1eabn<\/p>\n\n\n\n
Khi mua m\u00e1y bi\u1ebfn \u00e1p, m\u00e1y ph\u00e1t \u0111i\u1ec7n hay m\u1ed9t s\u1ed1 thi\u1ebft b\u1ecb \u0111i\u1ec7n; ng\u01b0\u1eddi ta th\u01b0\u1eddng th\u1ea5y c\u00f3 \u0111\u1ea1i l\u01b0\u1ee3ng Kva trong th\u00f4ng s\u1ed1 k\u1ef9 thu\u1eadt, ch\u1ee9 kh\u00f4ng ph\u1ea3i l\u00e0 kW hay W. Nh\u01b0ng kh\u00f4ng ph\u1ea3i ai c\u0169ng bi\u1ebft Kva l\u00e0 g\u00ec v\u00e0 n\u00f3 c\u00f3 m\u1ed1i li\u00ean quan g\u00ec v\u1edbi \u0111\u01a1n v\u1ecb kW kh\u00f4ng, c\u00f3 th\u1ec3 quy \u0111\u1ed5i t\u1eeb Kva sang kW kh\u00f4ng?. T\u1ea5t c\u1ea3 nh\u1eefng c\u00e2u h\u1ecfi \u0111\u00f3 s\u1ebd \u0111\u01b0\u1ee3c gi\u1ea3i \u0111\u00e1p trong b\u00e0i vi\u1ebft d\u01b0\u1edbi \u0111\u00e2y c\u1ee7a ch\u00fang t\u00f4i.<\/p>\n\n\n\n
\u0110\u01a1n v\u1ecb Kva l\u00e0 g\u00ec?<\/p>\n\n\n\n
Trong m\u1ea1ch \u0111i\u1ec7n xoay chi\u1ec1u, Kva l\u00e0 t\u00ean vi\u1ebft t\u1eaft c\u1ee7a t\u1eeb Kilo Volt Ampere; l\u00e0 \u0111\u01a1n v\u1ecb t\u00ednh c\u00f4ng su\u1ea5t bi\u1ec3u ki\u1ebfn hay c\u00f2n g\u1ecdi l\u00e0 c\u00f4ng su\u1ea5t to\u00e0n ph\u1ea7n c\u1ee7a m\u00e1y. Th\u00f4ng th\u01b0\u1eddng, \u0111\u01a1n v\u1ecb Kva th\u01b0\u1eddng \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng cho c\u00e1c lo\u1ea1i m\u00e1y ph\u00e1t \u0111i\u1ec7n.<\/p>\n\n\n\n
Trong m\u1ea1ch \u0111i\u1ec7n m\u1ed9t chi\u1ec1u, VA t\u01b0\u01a1ng \u0111\u01b0\u01a1ng v\u1edbi Watt. Nh\u01b0ng trong d\u00f2ng \u0111i\u1ec7n xoay chi\u1ec1u, VA th\u01b0\u1eddng \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng \u0111\u1ec3 t\u00ednh c\u00f4ng su\u1ea5t bi\u1ec3u ki\u1ebfn c\u00f2n Watt \u0111\u01b0\u1ee3c s\u1eed d\u1ee5ng \u0111\u1ec3 t\u00ednh c\u00f4ng su\u1ea5t th\u1ef1c. C\u00f4ng su\u1ea5t bi\u1ec3u ki\u1ebfn th\u01b0\u1eddng l\u1edbn h\u01a1n c\u00f4ng su\u1ea5t th\u1ef1c b\u1edfi n\u00f3 bao g\u1ed3m c\u1ea3 c\u00f4ng su\u1ea5t th\u1ef1c kW v\u00e0 c\u00f4ng su\u1ea5t ph\u1ea3n kh\u00e1ng kVar.<\/p>\n\n\n\n
Th\u00f4ng th\u01b0\u1eddng tr\u00ean th\u1ef1c t\u1ebf th\u00ec ng\u01b0\u1eddi ta ch\u1ec9 quan t\u00e2m \u0111\u1ebfn c\u00f4ng su\u1ea5t th\u1ef1c kW, l\u00e0 n\u0103ng l\u01b0\u1ee3ng h\u1eefu \u00edch chuy\u1ec3n \u0111\u1ed5i tr\u1ef1c ti\u1ebfp sang c\u01a1 n\u0103ng, nhi\u1ec7t n\u0103ng.<\/p>\n\n\n\n
M\u1ed1i quan h\u1ec7 v\u00e0 c\u00e1ch quy \u0111\u1ed5i gi\u1eefa 2 \u0111\u01a1n v\u1ecb Kva v\u00e0 KW<\/p>\n\n\n\n
Tr\u01b0\u1edbc khi t\u00ecm hi\u1ec3u v\u1ec1 m\u1ed1i quan h\u1ec7 v\u00e0 c\u00e1ch quy \u0111\u1ed5i gi\u1eefa 2 \u0111\u01a1n v\u1ecb n\u00e0y th\u00ec b\u1ea1n c\u1ea7n bi\u1ebft Kva l\u00e0 g\u00ec v\u00e0 KW l\u00e0 g\u00ec?. \u1ede ph\u1ea7n tr\u00ean, ch\u00fang ta \u0111\u00e3 c\u00f9ng t\u00ecm hi\u1ec3u Kva l\u00e0 g\u00ec?. V\u1eady c\u00f2n kW, b\u1ea1n \u0111\u00e3 hi\u1ec3u g\u00ec v\u1ec1 \u0111\u01a1n v\u1ecb n\u00e0y ch\u01b0a. \u0110\u00e2y l\u00e0 \u0111\u01a1n v\u1ecb \u0111o c\u00f4ng su\u1ea5t P trong h\u1ec7 \u0111o l\u01b0\u1eddng qu\u1ed1c t\u1ebf, l\u1ea5y theo t\u00ean c\u1ee7a James Watt. C\u00f4ng su\u1ea5t cho bi\u1ebft s\u1ef1 thay \u0111\u1ed5i n\u0103ng l\u01b0\u1ee3ng \u0394E trong 1 kho\u1ea3ng th\u1eddi gian \u0394t. C\u00f4ng su\u1ea5t P t\u1ea1i th\u1eddi \u0111i\u1ec3m t \u0111\u01b0\u1ee3c t\u00ednh theo c\u00f4ng th\u1ee9c P(t) = U(t).I(t), trong \u0111\u00f3 U(t), I(t) l\u00e0 c\u00e1c gi\u00e1 tr\u1ecb hi\u1ec7u d\u1ee5ng c\u1ee7a hi\u1ec7u \u0111i\u1ec7n th\u1ebf v\u00e0 c\u01b0\u1eddng \u0111\u1ed9 d\u00f2ng \u0111i\u1ec7n t\u1ea1i t khi ch\u00fang kh\u00f4ng l\u1ec7ch pha.<\/p>\n\n\n\n
\u0110\u1ec3 \u0111\u1ed5i t\u1eeb Kva sang kW c\u1ee7a m\u1ed9t m\u00e1y b\u1ea5t k\u1ef3 th\u00ec b\u1ea1n ph\u1ea3i bi\u1ebft h\u1ec7 s\u1ed1 c\u00f4ng su\u1ea5t cos(phi). C\u00f4ng th\u1ee9c t\u00ednh c\u00f4ng su\u1ea5t m\u00e1y bi\u1ebfn \u00e1p l\u00e0: P=U.I.cos phi.<\/p>\n\n\n\n
Trong \u0111\u00f3: P l\u00e0 c\u00f4ng su\u1ea5t (\u0111\u01a1n v\u1ecb: VA)<\/p>\n\n\n\n
U l\u00e0 hi\u1ec7u \u0111i\u1ec7n th\u1ebf (\u0111\u01a1n v\u1ecb: V)<\/p>\n\n\n\n
I l\u00e0 c\u01b0\u1eddng \u0111\u1ed9 d\u00f2ng \u0111i\u1ec7n (\u0111\u01a1n v\u1ecb: A)<\/p>\n\n\n\n
Phi l\u00e0 g\u00f3c l\u1ec7ch pha gi\u1eefa d\u00f2ng \u0111i\u1ec7n v\u00e0 hi\u1ec7u \u0111i\u1ec7n \u00e1p qua thi\u1ebft b\u1ecb ti\u00eau th\u1ee5 \u0111i\u1ec7n.<\/p>\n\n\n\n
Tr\u00ean th\u1ef1c t\u1ebf, \u0111a s\u1ed1 motor c\u00f3 cos phi=0,8; \u0111\u1ed9ng c\u01a1 c\u00f4ng su\u1ea5t 1 Kva ti\u00eau th\u1ee5 0,8kW \u0111i\u1ec7n th\u1ef1c. V\u00e0 ta r\u00fat ra m\u1ed1i quan h\u1ec7 gi\u1eefa c\u00f4ng su\u1ea5t th\u1ef1c kW v\u00e0 c\u00f4ng su\u1ea5t bi\u1ec3u ki\u1ebfn Kva l\u00e0: Kw = KVA x Cos (\u00d8). Cos phi = 0,2 \u2013 0,8 n\u00ean 1 Kva = 0,2 \u2013 0,8 Kw (t\u00f9y h\u1ec7 s\u1ed1 m\u00e1y m\u00e0 nh\u00e0 s\u1ea3n xu\u1ea5t quy \u0111\u1ecbnh).<\/p>\n\n\n\n
=> 1kW = 1kVA . 0,8 hay 1 kVA = 1 kW \/ 0,8<\/p>\n\n\n\n
Tr\u00ean \u0111\u00e2y l\u00e0 m\u1ed9t s\u1ed1 th\u00f4ng tin v\u1ec1 \u0111\u01a1n v\u1ecb Kva m\u00e0 ch\u00fang t\u00f4i mu\u1ed1n truy\u1ec1n t\u1ea3i t\u1edbi b\u1ea1n \u0111\u1ecdc, hy v\u1ecdng v\u1edbi nh\u1eefng th\u00f4ng tin n\u00e0y; b\u1ea1n c\u00f3 th\u1ec3 hi\u1ec3u r\u00f5 v\u1ec1 \u0111\u01a1n v\u1ecb \u0111o c\u00f4ng su\u1ea5t bi\u1ec3u ki\u1ebfn Kva, l\u1ef1a ch\u1ecdn thi\u1ebft b\u1ecb ph\u00f9 h\u1ee3p \u0111\u1ec3 s\u1eed d\u1ee5ng, tr\u00e1nh l\u00e3ng ph\u00ed \u0111i\u1ec7n n\u0103ng.<\/p>\n\n\n\n
<\/p>\n\n\n\n\n\n\n","protected":false},"excerpt":{"rendered":"
Ghi ch\u00fa: T\u00e0i li\u1ec7u tr\u00edch d\u1eabn Khi mua m\u00e1y bi\u1ebfn \u00e1p, m\u00e1y ph\u00e1t \u0111i\u1ec7n hay m\u1ed9t s\u1ed1 thi\u1ebft b\u1ecb \u0111i\u1ec7n; ng\u01b0\u1eddi ta th\u01b0\u1eddng th\u1ea5y c\u00f3 \u0111\u1ea1i l\u01b0\u1ee3ng Kva trong th\u00f4ng s\u1ed1 k\u1ef9 thu\u1eadt, ch\u1ee9 kh\u00f4ng ph\u1ea3i l\u00e0 kW hay W. Nh\u01b0ng kh\u00f4ng ph\u1ea3i ai c\u0169ng bi\u1ebft Kva l\u00e0 g\u00ec v\u00e0 n\u00f3 c\u00f3 m\u1ed1i li\u00ean quan […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":"","_disable_autopaging":false},"categories":[7],"tags":[],"class_list":["post-2921","post","type-post","status-publish","format-standard","hentry","category-vat-ly"],"_links":{"self":[{"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/posts\/2921","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/comments?post=2921"}],"version-history":[{"count":0,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/posts\/2921\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/media?parent=2921"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/categories?post=2921"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.vietlearn.org\/kien-thuc\/wp-json\/wp\/v2\/tags?post=2921"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}