The shielded signal wire is wrapped with a layer of shielding layer on the outside of the signal wire to play the role of anti-interference. Generally, the shielding layer is braided copper mesh or copper (aluminum). The shielding layer needs to be grounded when it is used, so as to lead the external interference signal to the ground by this layer, avoid the interference signal entering the inner conductor and reduce the loss of the transmission signal. Shielded signal line is applicable to power appliances, instruments and telecommunications equipment with AC rated voltage of 450/750V and below.