do harm to

If you let go a snake or a scorpion,you’re guilty of doing harm to your companion.

见蛇见蝎,不打作孽。

Multiple reignition makes the frequency and amplitude of overvoltage increase and might do harm to transformer coils by cumulative effects for its surge steepness.

多次重燃使得过电压频率和幅值均升高，会对变压器等绕组绝造。