Conventional electromagnetic current transformers(CT) possess high accuracy of steady-state electrical current measurement, but produce problems caused by magnetic saturation. By comparison, optical current transducers(OCT)have many advantages over CT and can measure fault transient current.

传统电磁式CT具有较高稳态电流测量精度，但存在饱和问题；而光学电流互感器(简称OCT)无此缺点，能测量故障暂态电流，但受温度应力引起的线性双折射的影响大，精度较低。

Iddt testing is another test approach that exposes faults by disposing the transient current flowing through the circuit under test. It can explore some faults that cannot be detected by voltage based testing and Iddq testing.

瞬态电流(IDDT)测试是一种从供电回路,通过观察被测电路所吸取的瞬间动态电流来检测故障的一种方法,被认为可以检测出一些经电压测试和(IDDQ)测试所不能检测的故障。