產品概述
直讀OCA介電損耗測試儀工作原理
1.“Q"的定義
Q表是(shi)根(gen)據串聯諧振原理設計,以(yi)諧振電壓的比值(zhi)來定(ding)位Q值(zhi)。
“Q"表示元(yuan)件或系統的“品質因數",其物理含義是在一(yi)個振蕩周期內(nei)貯存的能(neng)量與(yu)損(sun)耗的能(neng)量之比(bi)(bi)。對(dui)于電(dian)抗元(yuan)件(電(dian)感或電(dian)容)來(lai)說,即在測試(shi)頻率上(shang)呈現(xian)的電(dian)抗與(yu)電(dian)阻之比(bi)(bi)。
電容器容量的測量
A. 在(zai)測量范圍內的(de)小于主調電(dian)容(rong)量的(de)電(dian)容(rong)器的(de)測量
a.選一個適當的諧振電(dian)感接(jie)到(dao)“Lx"的兩端;
b.將調(diao)諧(xie)電(dian)(dian)容(rong)器調(diao)到(dao)最大值附近,令這個電(dian)(dian)容(rong)是C1,如未知電(dian)(dian)容(rong)是小(xiao)(xiao)數值的,C1應調(diao)到(dao)較(jiao)小(xiao)(xiao)電(dian)(dian)容(rong)值附近,以便達(da)到(dao)盡可(ke)能高的分辨率(lv);
c.調訊號源(yuan)的頻率,使測試回路(lu)諧振,令諧振器Q的讀數為(wei)Q1;
d.將(jiang)被測電(dian)容(rong)接在“Cx"兩端,調節(jie)調諧(xie)電(dian)容(rong)器,使測試電(dian)路(lu)再(zai)諧(xie)振,令新的(de)調諧(xie)電(dian)容(rong)值(zhi)為C2和指示Q值(zhi)為Q2。
被測電容的有(you)效電容為:Cx= C1-C2
電容(rong)器(qi)損耗角正切為:
電容器的(de)有效并聯電阻為:
C0為回(hui)路諧振電(dian)感的自身電(dian)容(rong)。
B.大于調(diao)諧(xie)電(dian)容量的電(dian)容器用可替代(dai)法測(ce)量
a. 取一只適當容量的(de)標準電容量,其容量為C3,將它接在“Cx"接線柱上;
b.按5A/a-c各(ge)測(ce)試(shi)步驟(zou);
c.取下標準電(dian)容(rong)(rong)器,將(jiang)被測電(dian)容(rong)(rong)接到(dao)“Cx"接線(xian)柱,調節調諧電(dian)容(rong)(rong)器到(dao)諧振,此時主調電(dian)容(rong)(rong)量讀數為(wei)C2,則Cx可由下式(shi)得到(dao):
固體:白云石:8; 鹽:6; 醋酸纖維素:3.7-7.5; 瓷器:5-7; 纖維素:3.9; 米及谷類:3-5; 砂:3-5;砂糖:3; 玻璃:3.7; 硫磺:3.4; 瀝青:2.7; 聚四氟乙烯塑料:1.8-2.2; 紙:2; 云母:6-8
氣(qi)態:空(kong)氣(qi)及(ji)其他(ta)氣(qi)體:1-1.2介(jie)(jie)電(dian)(dian)(dian)常(chang)(chang)數(shu)是相對(dui)介(jie)(jie)電(dian)(dian)(dian)常(chang)(chang)數(shu)與真空(kong)中(zhong)絕(jue)對(dui)介(jie)(jie)電(dian)(dian)(dian)常(chang)(chang)數(shu)乘積。如果有(you)高介(jie)(jie)電(dian)(dian)(dian)常(chang)(chang)數(shu)的(de)(de)(de)(de)材(cai)料放在(zai)電(dian)(dian)(dian)場中(zhong),電(dian)(dian)(dian)場的(de)(de)(de)(de)強度會在(zai)電(dian)(dian)(dian)介(jie)(jie)質(zhi)(zhi)內有(you)可觀(guan)的(de)(de)(de)(de)下降。理想(xiang)導(dao)體的(de)(de)(de)(de)相對(dui)介(jie)(jie)電(dian)(dian)(dian)常(chang)(chang)數(shu)為(wei)無(wu)窮(qiong)大。一(yi)個(ge)電(dian)(dian)(dian)容板中(zhong)充入介(jie)(jie)電(dian)(dian)(dian)常(chang)(chang)數(shu)為(wei)ε的(de)(de)(de)(de)物(wu)質(zhi)(zhi)后電(dian)(dian)(dian)容變大εr倍。電(dian)(dian)(dian)介(jie)(jie)質(zhi)(zhi)有(you)使空(kong)間(jian)比起實際(ji)尺寸變得更大或更小的(de)(de)(de)(de)屬性(xing)。例如,當(dang)一(yi)個(ge)電(dian)(dian)(dian)介(jie)(jie)質(zhi)(zhi)材(cai)料放在(zai)兩個(ge)電(dian)(dian)(dian)荷之間(jian),它(ta)(ta)會減(jian)少(shao)作用(yong)在(zai)它(ta)(ta)們(men)之間(jian)的(de)(de)(de)(de)力,就像它(ta)(ta)們(men)被(bei)(bei)移遠了(le)一(yi)樣。當(dang)電(dian)(dian)(dian)磁(ci)波穿過(guo)電(dian)(dian)(dian)介(jie)(jie)質(zhi)(zhi),波的(de)(de)(de)(de)速度被(bei)(bei)減(jian)小,有(you)更短的(de)(de)(de)(de)波長。根據(ju)物(wu)質(zhi)(zhi)的(de)(de)(de)(de)介(jie)(jie)電(dian)(dian)(dian)常(chang)(chang)數(shu)可以(yi)判別高分子材(cai)料的(de)(de)(de)(de)極性(xing)大小。通常(chang)(chang),相對(dui)介(jie)(jie)電(dian)(dian)(dian)常(chang)(chang)數(shu)大于(yu)3.6的(de)(de)(de)(de)物(wu)質(zhi)(zhi)為(wei)極性(xing)物(wu)質(zhi)(zhi);相對(dui)介(jie)(jie)電(dian)(dian)(dian)常(chang)(chang)數(shu)在(zai)2.8~3.6范圍內的(de)(de)(de)(de)物(wu)質(zhi)(zhi)為(wei)弱極性(xing)物(wu)質(zhi)(zhi);相對(dui)介(jie)(jie)電(dian)(dian)(dian)常(chang)(chang)數(shu)小于(yu)2.8為(wei)非(fei)極性(xing)物(wu)質(zhi)(zhi)。
直讀OCA介電損耗測試儀操作:
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