工頻介電常數介質損耗測定儀電(dian)(dian)(dian)橋在使(shi)用過(guo)程中(zhong)，靈敏(min)度直接影響電(dian)(dian)(dian)橋平穩衡(heng)的分辨(bian)程度，為保證測量準確度，希望(wang)電(dian)(dian)(dian)橋靈敏(min)度達到(dao)一定(ding)的水平。通常情況下(xia)電(dian)(dian)(dian)橋靈敏(min)度與測量電(dian)(dian)(dian)壓，標準電(dian)(dian)(dian)容量成正比。

    在(zai)下面的計(ji)算公式中(zhong)，用戶(hu)可根(gen)據實際情況(kuang)估算出電(dian)橋(qiao)靈敏度水(shui)平(ping)，在(zai)這個水(shui)平(ping)上的電(dian)容與介(jie)質損耗因(yin)數的微小變化都能夠(gou)反應出來。

     ΔC/C或Δtgδ=Ig/UωCn(1+Rg/R4+Cn/Cx)

式(shi)中: U 為(wei)測量(liang)電壓                              伏特  (V)

      ω為角頻率2πf=314(50Hz)                               

     Cn標準電容(rong)器容(rong)量                          法拉(F) 

     Ig通(tong)用指(zhi)零儀(yi)的(de)電(dian)流5×10-10                  安培(A)  

     Rg平(ping)衡指零儀內阻約1500                    歐(ou)姆(mu)(Ω)

     R4橋臂R4阻值3183                         歐(ou)姆(mu)(Ω)

     Cx被測試品(pin)電容值                           法拉(pF)

工頻介電常數介質損耗測定儀與R4橋(qiao)(qiao)臂(bei)并聯，測量數值為正(zheng)損耗因數。結構采用了雙層屏(ping)蔽。并通(tong)過(guo)輔(fu)橋(qiao)(qiao)的(de)(de)輔(fu)助平(ping)(ping)衡(heng)(heng)(heng)，消除寄生(sheng)參數對(dui)電(dian)(dian)(dian)橋(qiao)(qiao)平(ping)(ping)衡(heng)(heng)(heng)的(de)(de)影響。輔(fu)橋(qiao)(qiao)由(you)電(dian)(dian)(dian)位(wei)(wei)自動(dong)(dong)電(dian)(dian)(dian)位(wei)(wei)跟蹤器(qi)與內層屏(ping)蔽（S）組(zu)成(cheng)。自動(dong)(dong)跟蹤器(qi)由(you)電(dian)(dian)(dian)子(zi)元(yuan)器(qi)件(jian)組(zu)成(cheng)。它在(zai)橋(qiao)(qiao)頂B處(chu)取一輸入電(dian)(dian)(dian)壓，通(tong)過(guo)放大(da)后，在(zai)內屏(ping)蔽（S）產生(sheng)一個與B電(dian)(dian)(dian)位(wei)(wei)相等的(de)(de)電(dian)(dian)(dian)壓。當電(dian)(dian)(dian)橋(qiao)(qiao)在(zai)平(ping)(ping)衡(heng)(heng)(heng)時，A,B,S三(san)點電(dian)(dian)(dian)位(wei)(wei)必(bi)然相等，從而達(da)到自動(dong)(dong)跟蹤的(de)(de)目(mu)的(de)(de)。本(ben)電(dian)(dian)(dian)橋(qiao)(qiao)在(zai)平(ping)(ping)衡(heng)(heng)(heng)過(guo)程中，輔(fu)橋(qiao)(qiao)采用自動(dong)(dong)電(dian)(dian)(dian)位(wei)(wei)跟蹤，在(zai)主橋(qiao)(qiao)平(ping)(ping)衡(heng)(heng)(heng)過(guo)程的(de)(de)同時，輔(fu)橋(qiao)(qiao)也自動(dong)(dong)跟蹤始終處(chu)于平(ping)(ping)衡(heng)(heng)(heng)的(de)(de)狀態，用戶(hu)只要對(dui)主橋(qiao)(qiao)平(ping)(ping)衡(heng)(heng)(heng)進行(xing)操作就能(neng)得(de)到可(ke)靠的(de)(de)所需數據。同時也有效的(de)(de)抑(yi)制了電(dian)(dian)(dian)壓波動(dong)(dong)對(dui)平(ping)(ping)衡(heng)(heng)(heng)所帶來的(de)(de)影響。在(zai)指零(ling)部分，采用了指針式(shi)電(dian)(dian)(dian)表指示，視覺直觀(guan)，分辨清楚，克服(fu)了以往振動(dong)(dong)式(shi)檢(jian)流計的(de)(de)缺(que)點。