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判断(duan)(duan)(duan)管(guan)(guan)(guan)道(dao)(dao)(dao)(dao)(dao)(dao)(dao)阴(yin)(yin)(yin)极(ji)保(bao)(bao)护(hu)是(shi)否(fou)充分或是(shi)否(fou)过保(bao)(bao)护(hu)，依(yi)据的(de)(de)(de)是(shi)管(guan)(guan)(guan)道(dao)(dao)(dao)(dao)(dao)(dao)(dao)的(de)(de)(de)断(duan)(duan)(duan)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)位(wei)(wei)。然而，在(zai)某些(xie)情况下，作用(yong)(yong)在(zai)管(guan)(guan)(guan)道(dao)(dao)(dao)(dao)(dao)(dao)(dao)上的(de)(de)(de)所(suo)有电(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)源(yuan)(yuan)没有办法同步中(zhong)(zhong)断(duan)(duan)(duan)，如(ru)采用(yong)(yong)牺牲阳极(ji)阴(yin)(yin)(yin)极(ji)保(bao)(bao)护(hu)的(de)(de)(de)管(guan)(guan)(guan)道(dao)(dao)(dao)(dao)(dao)(dao)(dao)。即便(bian)是(shi)阴(yin)(yin)(yin)极(ji)保(bao)(bao)护(hu)系统(tong)可以同步中(zhong)(zhong)断(duan)(duan)(duan)，如(ru)用(yong)(yong)GPS同步的(de)(de)(de)外加电(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)的(de)(de)(de)同步中(zhong)(zhong)断(duan)(duan)(duan)，由于(yu)管(guan)(guan)(guan)道(dao)(dao)(dao)(dao)(dao)(dao)(dao)不同位(wei)(wei)置的(de)(de)(de)极(ji)化程(cheng)度不同，电(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)中(zhong)(zhong)断(duan)(duan)(duan)后(hou)，管(guan)(guan)(guan)道(dao)(dao)(dao)(dao)(dao)(dao)(dao)各(ge)部位(wei)(wei)之间的(de)(de)(de)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)流(liu)仍无法消除，这(zhei)也(ye)会给断(duan)(duan)(duan)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)位(wei)(wei)测(ce)量(liang)带来误差(cha)，研究(jiu)发现该误差(cha)为(wei)10～30mV。用(yong)(yong)地紧张造成多条管(guan)(guan)(guan)道(dao)(dao)(dao)(dao)(dao)(dao)(dao)、高(gao)压输电(dian)(dian)(dian)(dian)(dian)(dian)(dian)线路、电(dian)(dian)(dian)(dian)(dian)(dian)(dian)力机车系统(tong)经(jing)常共用(yong)(yong)一(yi)个管(guan)(guan)(guan)廊，各(ge)种(zhong)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)气化设施以及(ji)各(ge)条管(guan)(guan)(guan)道(dao)(dao)(dao)(dao)(dao)(dao)(dao)的(de)(de)(de)阴(yin)(yin)(yin)极(ji)保(bao)(bao)护(hu)系统(tong)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)源(yuan)(yuan)都(dou)会成为(wei)干扰源(yuan)(yuan)，而同步中(zhong)(zhong)断(duan)(duan)(duan)这(zhei)些(xie)干扰源(yuan)(yuan)更不可能，这(zhei)就给管(guan)(guan)(guan)道(dao)(dao)(dao)(dao)(dao)(dao)(dao)断(duan)(duan)(duan)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)位(wei)(wei)的(de)(de)(de)测(ce)量(liang)带来了困难。为(wei)克服这(zhei)些(xie)环境因素给电(dian)(dian)(dian)(dian)(dian)(dian)(dian)位(wei)(wei)测(ce)量(liang)带来的(de)(de)(de)困难，传(chuan)统(tong)的(de)(de)(de)试片法又重新得到(dao)人(ren)们的(de)(de)(de)关注，用(yong)(yong)试片法进行(xing)管(guan)(guan)(guan)道(dao)(dao)(dao)(dao)(dao)(dao)(dao)断(duan)(duan)(duan)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)电(dian)(dian)(dian)(dian)(dian)(dian)(dian)位(wei)(wei)的(de)(de)(de)测(ce)量(liang)也(ye)得到(dao)了进一(yi)步的(de)(de)(de)研究(jiu)。

测量方法
①试片法断电电位测量有两种方法，一种是将参比电极与试片组装在一起组成极化探头进行测量，称为极化探头法；另一种是将试片固定在参比管上，利用便携式参比电极进行测量，称为参比管试片法。当使用极化探头法时，参比电极中的电解液会逐渐渗漏直至参比电极失效，同时，渗漏出来的电解液会改变试片所处环境，当硫酸铜电解液与试片接触时，会发生置换反应，试片表面被铜覆盖，改变了其极化特性，参比电极电位漂移时也不易察觉。采用参比管，由于参比管的屏蔽作用，利用便携式参比电极在地表就可以进行测量，避免漏液带来的问题。

电位测量中注意的问题

①当需要测量两个测试桩之间的管道极化电位时，需要将试片移到两测试桩的中间位置，受导线电阻影响，进入试片的电流密度会减小，试片的极化电位也会减小。同时，如果万用表的内阻不足够大，通电电位值也减小。因此，尽量避免将试片移开测试桩位置。当管道有开挖补漏时，可以直接在涂层漏点处连接测试片。

②一般情况下，可以用测试桩之间某点的通电电位减去测试桩位置的通、断电电位之差(IR降)，来计算该点的管道极化电位。

③采用参比管试片法进行测量时，参比管内要填充密实的土壤，将参比电极位于参比管上部，并与参比管内的土壤紧密接触，读取试片的通、断电电位。如果数值相差不大，说明参比电极号试片之间的IR降不大；如果数值相差较大，应取试片断电电位作为管道的保护电位。在存在动态杂散电流干扰的管道附近，如果试片的自然电位是稳定的，说明杂散电流不会形成电位梯度，对试片的断电电位测量没有影响。受动态杂散电流的影响，试片的通电电位有时会比断电电位更正。