全自动变压器绕组直流电阻快速测量仪

根据电力变压器绕组直流电阻的测量特点,针对目前变压器绕组直流电阻测量仪存在的问题,笔者提出了"自动切换被测绕组电路"法,即测量人员连接好全部测试夹钳后,由CPU控制功率继电器完成各相绕组的测量,减少了总测量时间和测量人员的劳动强度。笔者还提出了主动放电方法,在保证尽可能短的放电时间的前提下降低了反向电压的幅值,保护了设备和人员的安全。采用格罗布斯(Grubbs)准则剔除粗大误差,并给出了变压器直流电阻的最小二乘公式。测试结果表明,应用格罗布斯准则和直流电阻最小二乘公式可最大限度地减小现场干扰和偶然误差对测量结果的影响。

Automatic Transformer DC Resistance Instrument Based on Dual CPU Structure

According to the character of DC resistance measurement of power transformer windings,an automatic switch circuit of measured winding is presented to overcome the shortcoming of conventional transformer DC resistance instrument.In the measurement process,this technique needs only to change the transformer tap-switch,and the internal power relay automatically accomplishes the measurement of three-phase windings,which greatly decreases the intensity of the labor.An initiative discharge method is proposed to reduce inverse voltage peak in shortest time and protect the equipment and person.Moreover,Grubbs rule is applied to remove large error and a least squares formula of transformer DC resistance is also given.Test results show that the effects due to field interference and accidental error on measurement results can be minimized by using the Grubbs rule and least square formula of DC resistance.