穩壓器(qi)是一(yi)種能(neng)自動調整(zheng)輸出電(dian)(dian)(dian)(dian)壓的(de)供(gong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)路或供(gong)電(dian)(dian)(dian)(dian)設(she)備，其作用是將波動較大和達不(bu)到電(dian)(dian)(dian)(dian)器(qi)設(she)備要求的(de)電(dian)(dian)(dian)(dian)源(yuan)電(dian)(dian)(dian)(dian)壓穩定(ding)在它的(de)設(she)定(ding)值范圍內，使各種電(dian)(dian)(dian)(dian)路或電(dian)(dian)(dian)(dian)器(qi)設(she)備能(neng)在額定(ding)工作電(dian)(dian)(dian)(dian)壓下(xia)正常工作。

最(zui)初的電力穩(wen)壓器是靠繼電器的跳動(dong)(dong)穩(wen)定(ding)電壓的。當(dang)電網電壓出現(xian)波動(dong)(dong)時(shi)，電力穩(wen)壓器的自動(dong)(dong)糾正電路(lu)(lu)啟動(dong)(dong)，使內部繼電器動(dong)(dong)作。迫使輸出電壓保持在設定(ding)值附近(jin)，這(zhe)種電路(lu)(lu)優(you)點是電路(lu)(lu)簡單，缺(que)點是穩(wen)壓精度不高并且每一(yi)次繼電器跳動(dong)(dong)換擋，都會使供電電源發生一(yi)次瞬(shun)時(shi)的中斷(duan)并產(chan)生火花(hua)干擾。

這對電(dian)(dian)腦設備的讀寫工作干擾很大，容(rong)易造(zao)成電(dian)(dian)腦出現錯誤信號，嚴重時還(huan)會使硬盤損(sun)壞。

高(gao)質量的小型(xing)穩(wen)(wen)壓(ya)器，大(da)多采用(yong)電(dian)機拖(tuo)動碳刷的方法(fa)穩(wen)(wen)定(ding)電(dian)壓(ya)，這種穩(wen)(wen)壓(ya)器對電(dian)器設備產(chan)生的干擾很小穩(wen)(wen)壓(ya)精度相對較(jiao)高(gao)。