一(yi)款帶(dai)漏電保(bao)護(hu)的延時(shi)插座電路
帶漏電保護的延時dc電源插痤（電(dian)路如下圖所(suo)示）主要由漏電(dian)檢測和(he)可調式長延(yan)(yan)時電(dian)路組成，按下SB1，無漏電(dian)現(xian)象，VT1處于零偏置(zhi)而飽(bao)和(he)導通(tong)，VT2截止，VT3導通(tong)，繼電(dian)器K吸合(he)，其動合(he)觸點K1-1閉(bi)合(he)并(bing)自(zi)鎖而供電(dian)，動斷(duan)觸點K1-2斷(duan)開，并(bing)使C3放電(dian)完畢，提高延(yan)(yan)時精度。
在dc電(dian)(dian)(dian)(dian)源(yuan)(yuan)插座(zuo)延(yan)時電(dian)(dian)(dian)(dian)路(lu)中(zhong)，充(chong)電(dian)(dian)(dian)(dian)電(dian)(dian)(dian)(dian)容Cx是由(you)C3、VDI0、 VT4組(zu)成的電(dian)(dian)(dian)(dian)容容量(liang)倍增器，可(ke)等效成很大(da)的電(dian)(dian)(dian)(dian)容；VT4采用不同(tong)β值的晶(jing)體三極管，則可(ke)組(zu)成長延(yan)時時間。調節R9可(ke)改變dc電(dian)(dian)(dian)(dian)源(yuan)(yuan)插座(zuo)延(yan)時電(dian)(dian)(dian)(dian)路(lu)的時間常數，一般取RC充(chong)電(dian)(dian)(dian)(dian)曲線(xian)(xian)近直線(xian)(xian)段[ (0.6~1.5) T]均可(ke)，隨著時間推(tui)進，VT2逐步(bu)導通，VT3截止，繼電(dian)(dian)(dian)(dian)器K釋(shi)放而斷(duan)電(dian)(dian)(dian)(dian)。
當使用dc電源插座的電器有漏電現象時，由R3、R4、VD5、VD6等組成的漏電檢測電路、提供VT1的夾斷電壓，可以使UD電(dian)位上升，VT2飽和導通，VT2很快截止，繼電(dian)器釋放而斷電(dian)，達(da)到漏電(dian)保護(hu)的目(mu)的。紅色發(fa)光管LED作供電(dian)指示。
dc電源插座元器件選擇：變壓器(qi)T可根據繼電(dian)器(qi)工作電(dian)壓來決定；繼電(dian)器(qi)應有單(dan)獨動合及動斷觸點；用電(dian)器(qi)的功率由觸點允許(xu)通(tong)過的電流決定。C3應(ying)盡量選(xuan)用(yong)漏電(dian)電(dian)流(liu)小的電(dian)容。VT1選(xuan)用(yong)飽和漏電(dian)電(dian)流(liu)I為1~3mA，夾(jia)斷電(dian)(dian)壓的結型場效應管，采用三孔(kong)dc電(dian)(dian)源插座供電(dian)(dian)。
