Loophole in the Measurement of Conducted Emission from Broadband Power-Line Communications using Impedance Stabilization Network

インピーダンス　アンテイカ　カイロモウ　ヲ　モチイタ　コウタイイキ　デンリョクセン　ハンソウ　ツウシン　セツビ　ノ　デンドウ　ボウガイハ　ソクテイ　ノ　モウテン

キタガワ, マサヒロ

Kitagawa, Masahiro

漏洩電磁界

伝導妨害波

コモンモード

差動モード

不平衡

モード変換

縦電圧変換損(LCL)

インピーダンス安定化回路網(ISN)

power-line communications (PLC)

radiated emission

conducted emission

common mode

differential mode

unbalance

mode conversion

longitudinal conversion loss (LCL)

impedance stabilization network (ISN)

The radiated emission due to the in-house broadband power-line communications (PLC) is caused by the common-mode (CM) currents on the power-line network. There are two origins of the CM currents; The one is caused by the unbalance of the PLC modem itself and injected from the modem to the outlet. The other is converted from the DM signal current at the unbalanced elements on the power-line network. Japanese PLC regulation ristricts the CM current measured using the impedance stabilization network (ISN) with the DM impedance of 100 ohm, CM impedance of 25 ohm, and the longitudinal conversion loss (LCL) of 16dB, which is determined from the LCL measured at the outlets and intended to emulate the in-house power-linen network. However, the PLC modems which are type-approved under the regulation and avaiable in the market cause the radiated emission more than 20dB larger than intended. The direct cause of the excessive emission is the excessive DM signal of the PLC modems. Why the CM current measurement using the ISN allows the excessive DM signal is clarified.