1313357 九、發明說明： 【發明所屬之技術領域】 本發明係關於一種電流量測裝置，尤其是一種具有比 流器（current transformer, CT)之電流量測裝置。 【先前技術】 現今電流量測常用的方法包括比流器法、電阻壓降 法、霍爾（Hall)元件法。其中，電阻壓降法無法與待測 物分隔，而只能採用固定於待測物之設計方式。相較之下， 比流器法與霍爾元件法則無此限制’而適用於可移動之儀 器。又，就比流器法與霍爾元件法之比較而言，雖然霍爾 元件法具有較佳之準確度，但是其電路較為複雜、成本較 高昂，同時，其適用之動態範圍較窄。因此，比流器法仍 有其產業利用上之價值。 ° 第一圖係顯示一典型比流器2〇之結構示意圖，而第二 圖係此比流器運作之等效電路圖。如圖中所示，一待測電 流源I (未圖示於第一圖）係連接至一導線1〇。此導線1〇 就電路上而言，可以相互串接之電’rl與電感u表示， 而與待測電流源I構成一初級迴路。 此比流器20就結構上而言，係由一環狀磁芯（c〇R) 22與一次級線圈24所構成。導線1〇係貫穿環狀磁芯 之中心孔22a，而次級線圈24係纏繞於環狀磁芯22。而如 第-圖所示，此次級線圈24就電路上而言，可視為相互串 接之一次級線圈電阻r2與一次級線圈電感L2。通常，另 有一電壓偵測電阻R串接至前述次級線圈電阻r2與次級線 5 圈電感L2 ’而構成一次級迴路20。 基本上’導線10係透過磁芯（c〇re) 22磁性輕合至 次級線圈24。因此，產生於初級迴路上的電流丨丨係透過 此磁芯22 ’在次級迴路20上產生一電動勢（e i ectr〇m〇t i ve force ) ’並藉由此電動勢在次級迴路2 〇上形成另一個電流 i2。 不過，如圖中所示，導線10與次級線圈24間亦會構 成-耦合電容C ’而在次級線圈24上產生電容搞合訊號。 基本上，在低電壓或是低頻量測之情況下，由於由導線1〇 所引發之電場干舰獨顯，因此，量_電絲合訊號 之問題並不突顯。但是，當用於量測高電壓或是高頻之電 流時’由導線10所引發之電容輕合訊號就會變得明顯。此 訊號會與翻m餘重疊，而使制之精顧嚴重下降。 於是，如何提高比流n制方式之峨縣比，以有 =應用於高電壓或是高頻量測之環境，將會對於比流器之 應用價值的提升，有極為重要之影響。 【發明内容】 轉明之目的在於提供—種電流量測裝置，以比 /進仃電流制。並且，此電_ ^ 容輕合訊叙干擾。 u w級防止電 1313357 -隔離層與-放大電路。其中’環狀磁芯係環繞待測電路。 次?線圈係纏繞環狀磁芯。隔離層係實質上遮蔽次級線圈 與環狀磁S ’以崎次級線圈與待測電路間之靜電輕合。 並且、’隔離層上形成有一開口，以消減因此隔離層所造成 之滿流（eddy euiTent)損耗。放大電路係連接次級線圈， 以放大次級線圈上之電流。 本發明亦提供-種比流H，此比流^包括一環狀磁 怒、一次級線圈與一隔離層。其中，雜磁芯係環繞待測 電路。次級線圈雜繞環狀磁芯。祕層係實質上遮蔽次 級線圈與環狀磁芯’以崎顿、_與制電賴之靜電 輕合…開π係形成於隱層上，因麟層所造成 之渦流（eddy current)損耗。 關於本發明之優點與精神可以藉由以下的發明詳述及 所附圖式得到進一步的瞭解。 【實施方式】 请參照第二圖所示，係本發明之電流量測裝置一較佳 實施例之電路示意圖。如圖中所示，此電流量測裝置包括 一環狀磁芯120、一次級線圈140、一隔離層160與一放大 電路200。其中，環狀磁芯12〇、次級線圈mo與隔離層 160 係構成一比流器（current transformer, CT) 100。 放大電路200係連接至次級線圈i4〇，以放大次級線圈140 上之電流訊號。次級線圈140的兩端係連接至放大電路 200，並且’在次級線圈14〇係中間接地G。同時，此比流 器100並設置有一負載電阻170並聯於次級線圈140。 同時請參照第五與五A圖，係第三圖中比流器1〇〇的 結構示意圖。如圖中所示，環狀磁芯12G係環繞待測電路 50，而次級線圈14〇係纏繞環狀磁芯12〇。此次級線圈14〇 之兩端係分別連接至一輸出接腳15〇a與15〇b，以連接至 放大電路200。為了使次級線圈⑽巾間接地，此比流器 100並製作有-接地接腳190連接至次級線圈14〇之中間 位置。 隔離層⑽係實質上遮蔽次、級線圈14〇與環狀磁芯 120。此隔離層16〇可以由導電石墨、銀、鋼等導電材質， 以蒸鑛等方式所製作於—娜外殼上，然亦不限於此。 由於此隔離層160之存在’縣會軸於制電路5〇 與次級線圈140間之搞合電容（請參照第二圖所示），改為 形成於待測電路50與隔離層16〇間，而可以有效 二 線圈U0與待測電路50間之靜電耦合，避免在次 140上產生不必要之電容耦合訊號。 惟，若是隔離層160完全遮蔽環狀磁芯12〇，將導致 渦流（eddy current)耗損之產生，而影響比流器1〇〇之 感應訊號的品質。因此，本發明必須在隔離層16〇上形成 —開口 162，以消除因隔離層160之設置所造成之渴流損 耗。基本上’此開口 162之位置並未有特別之限制。秋而， 就-較佳實施例而言，如圖中所示，為兼顧製作之便利性 與消減渦流損耗之有效性，此開口 162可為一環狀切口， 位於對應於環狀磁芯120之内侧壁處。 值得注意的是，由於此開π 162之存在，次級線圈14〇 與待測電路50間仍然可能存在靜電麵合，而在次級線圈 140上產生少量電谷輛合訊说。為了進一步去除此電容輛 合訊號，前述放大電路200可以採用一差動放大電路（如 第六圖所示）’專以放大由与、狀磁芯12〇感應待測電流（即 由磁場感應）所生之差動訊號。同時，次級線圈140係採 中間接地之設計，以有效排除來自待測電路50之靜電輕合 訊號。 請參照第四圖所示，係本發明之電流量測裝置另一較 佳實施例之電路圖。此電流量測裝置包括一環狀磁芯 120、一次級線圈140、一隔離層160、二負裁電阻 與170b與一放大電路200。其中，環狀磁芯120、次級線 圈140與隔離層160構成一比流器1〇〇。放大電路2〇〇係 連接至次級線圈140 ’以放大次級線圈14〇上之電流訊號。 相較於第二圖之實施例中僅具有一負載電阻，本 實施例係使用二互相串接之負載電阻n〇a與170b，而此 二負載電阻170a與170b係並聯於次級線圈14(^此外， 相較於第三圖之實施例中次級線圈14〇係中間接地，如第 四圖所示，本實施例除了可以將二負載電阻17如與17牝 相接之接點接地G以排除來自待測電路5〇之靜電耦合訊號 外；如第四A圖所示，本實施例亦可以在二負載電阻17〇a 與170b間串接一中間接地之可變電阻172，以排除來自待 測電路50之靜電耦合訊號。 综上所述，本發明之比流器1〇〇透過隔離層16〇之使 用可以有效降低靜電耦合訊號之產生，同時搭配開口 之製作’ y以避免渦流耗損對於感應品f的影響。此設計 特別對於高·與高頻環境之制有其實益。惟在隔離層 160製作開口 162’尚可能使部分靜電麵合訊號得以穿透隔 離層160而影響次、級線圈14〇上之電流訊號。因此，本發 明同時使用差動放大電路2〇〇，搭配次級線圈14〇中間接 地之電路設計（或是將二負载電阻與通相接之接 點接地）’以進一步排除來自待測電路5〇之靜電耦合訊號。 以上所述係利用較佳實施例詳細說明本發明，而非限 制本發明之範®，而且熟知此類技藝人士皆能明瞭，適當 而作些微的改變及娜’仍將不失本發明之要義所在，亦 不脫離本發明之精神和範圍。 【圖式簡單說明】 第一圖係—典型比流器之結構示意圖。 第二圖係第一圖之比流器運作之等效電路圖。 第三_、本伽比流H—較佳實_之等效電路圖。 第四圖係本發明比流II另—較佳實_之等效電路 圖。 第四A圖係本發明比流器又一較佳實施例之等效電路 圖。 第五圖係本發明m較佳實蘭之結構示意圓。 第五a圖係第五圖之比流器的内部構造示意圖。 第六圖係-典型差動放大電路之電路圖。 1313357 【主要元件符號說明】 導線10 比流器20 環狀磁芯22 次級線圈24 中心孔22a 比流器100 環狀磁芯120 次級線圈140 隔離層160 放大電路200 待測電路50 輸出接腳150a, 150b 開口 162 接地接腳190 負載電阻 170,170a，170b 111313357 IX. Description of the Invention: [Technical Field] The present invention relates to a current measuring device, and more particularly to a current measuring device having a current transformer (CT). [Prior Art] Common methods for current measurement include the current comparator method, the resistance voltage drop method, and the Hall element method. Among them, the resistance voltage drop method cannot be separated from the object to be tested, but only the design method fixed to the object to be tested. In contrast, the flow comparator method and the Hall element rule do not have this limitation, and are applicable to movable instruments. Moreover, in comparison with the flow method and the Hall element method, although the Hall element method has better accuracy, the circuit is more complicated and costly, and at the same time, the applicable dynamic range is narrow. Therefore, the flow comparator method still has its value in industrial utilization. ° The first figure shows the structure of a typical current transformer 2〇, and the second figure shows the equivalent circuit diagram of the current comparator operation. As shown in the figure, a current source I to be tested (not shown in the first figure) is connected to a wire 1〇. The conductor 1 〇 can be represented by an electrical connection ’rl and an inductance u connected to each other, and forms a primary loop with the current source I to be tested. The current comparator 20 is structurally composed of a toroidal core (c〇R) 22 and a primary coil 24. The wire 1 is wound through the center hole 22a of the annular core, and the secondary coil 24 is wound around the annular core 22. As shown in the first figure, the secondary coil 24 can be regarded as one of the secondary coil resistors r2 and the primary coil inductor L2 in series with each other. Usually, another voltage detecting resistor R is connected in series to the aforementioned secondary coil resistor r2 and the secondary line 5 loop inductor L2' to constitute the primary circuit 20. Basically, the wire 10 is magnetically coupled to the secondary coil 24 through a magnetic core. Therefore, the current enthalpy generated on the primary circuit generates an electromotive force (ei ectr〇m〇ti ve force ) on the secondary circuit 20 through the magnetic core 22' and thereby the electromotive force is applied to the secondary circuit 2 Another current i2 is formed. However, as shown in the figure, a coupling capacitor C' is formed between the wire 10 and the secondary coil 24 to generate a capacitance matching signal on the secondary coil 24. Basically, in the case of low-voltage or low-frequency measurement, the problem of the amount of wire-and-wire is not highlighted because the electric field caused by the wire 1〇 is unique. However, when used to measure high voltage or high frequency currents, the capacitive coupling signal caused by the wire 10 becomes apparent. This signal will overlap with the over-the-counter, and the system will be seriously reduced. Therefore, how to improve the ratio of the county to the county of the flow system, with the application of = in the environment of high voltage or high frequency measurement, will have an extremely important impact on the application value of the flow comparator. SUMMARY OF THE INVENTION The purpose of the clarification is to provide a current measuring device, which is made by a ratio of / current. Moreover, this electric _ ^ is light and confession. u w level to prevent electricity 1313357 - isolation layer and - amplification circuit. Wherein the annular core surrounds the circuit under test. The secondary coil is wound around the toroidal core. The isolation layer substantially shields the secondary coil from the annular magnetic S' from the electrostatic interaction between the secondary coil and the circuit under test. And, an opening is formed on the isolation layer to reduce the eddy euiTent loss caused by the isolation layer. The amplifying circuit is connected to the secondary coil to amplify the current on the secondary coil. The present invention also provides a specific flow H comprising a ring-shaped magnetic anger, a primary coil and an isolation layer. Among them, the magnetic core surrounds the circuit to be tested. The secondary coil is wound around the toroidal core. The secret layer essentially shields the secondary coil from the toroidal core to 'salt, _ and the electricity generated by the electricity system. The π system is formed on the hidden layer, and the eddy current is lost due to the lining. . The advantages and spirit of the present invention will be further understood from the following detailed description of the invention. [Embodiment] Please refer to the second figure, which is a circuit diagram of a preferred embodiment of the current measuring device of the present invention. As shown in the figure, the current measuring device comprises an annular core 120, a primary coil 140, an isolation layer 160 and an amplification circuit 200. The annular core 12 〇, the secondary coil mo and the isolation layer 160 constitute a current transformer (CT) 100. The amplifying circuit 200 is connected to the secondary coil i4 〇 to amplify the current signal on the secondary coil 140. Both ends of the secondary coil 140 are connected to the amplifying circuit 200, and 'grounds G' in the middle of the secondary coil 14. At the same time, the current transformer 100 is provided with a load resistor 170 in parallel with the secondary coil 140. Please also refer to the fifth and fifth A diagrams, which is a schematic diagram of the structure of the current comparator 1〇〇 in the third diagram. As shown in the figure, the toroidal core 12G surrounds the circuit under test 50, and the secondary coil 14 is wound around the toroidal core 12A. Both ends of the secondary coil 14A are connected to an output pin 15a and 15B, respectively, for connection to the amplifying circuit 200. In order to indirectly make the secondary coil (10), the current transformer 100 is formed with a grounding pin 190 connected to the intermediate position of the secondary coil 14A. The spacer layer (10) substantially shields the secondary, secondary coils 14A and the toroidal core 120. The spacer layer 16 can be made of a conductive material such as conductive graphite, silver or steel, and is formed on the outer shell by steaming or the like, but is not limited thereto. Due to the existence of the isolation layer 160, the county capacitor is formed between the circuit 5 and the secondary coil 140 (refer to the second figure), and is formed between the circuit under test 50 and the isolation layer 16 The electrostatic coupling between the two coils U0 and the circuit under test 50 can be effectively prevented, thereby avoiding unnecessary capacitive coupling signals on the secondary 140. However, if the isolation layer 160 completely shields the toroidal core 12, it will cause eddy current wear and affect the quality of the inductive signal of the current collector. Therefore, the present invention must form an opening 162 in the spacer layer 16 to eliminate the thirst loss caused by the arrangement of the spacer layer 160. Basically, the position of this opening 162 is not particularly limited. In the autumn, as in the preferred embodiment, as shown in the figure, in order to balance the convenience of fabrication and the effectiveness of eddy current loss, the opening 162 may be an annular slit corresponding to the annular core 120. At the inner side wall. It is worth noting that due to the presence of the opening π 162, there may still be an electrostatic junction between the secondary coil 14 〇 and the circuit under test 50, and a small amount of electricity is generated on the secondary coil 140. In order to further remove the capacitor signal, the amplifying circuit 200 can adopt a differential amplifying circuit (as shown in FIG. 6) to specifically amplify the current to be measured by the magnetic core 12 (ie, induced by the magnetic field). The differential signal generated. At the same time, the secondary coil 140 is designed with an intermediate ground to effectively eliminate the electrostatic light coupling signal from the circuit under test 50. Referring to Figure 4, there is shown a circuit diagram of another preferred embodiment of the current measuring device of the present invention. The current measuring device comprises a toroidal core 120, a primary coil 140, an isolation layer 160, two negative cutting resistors 170b and an amplifying circuit 200. The annular core 120, the secondary coil 140 and the isolation layer 160 constitute a current divider 1〇〇. The amplifying circuit 2 is connected to the secondary coil 140' to amplify the current signal on the secondary coil 14''. Compared with the embodiment of the second figure, there is only one load resistor. In this embodiment, two load resistors n〇a and 170b are connected in series, and the two load resistors 170a and 170b are connected in parallel to the secondary coil 14 ( In addition, in the embodiment of the third embodiment, the secondary coil 14 is grounded in the middle, as shown in the fourth figure, in this embodiment, the second load resistor 17 can be grounded at the contact point of the junction with the 17 G. In order to eliminate the electrostatic coupling signal from the circuit 5 to be tested; as shown in FIG. 4A, the present embodiment can also connect an intermediate grounded variable resistor 172 between the two load resistors 17A and 170b to eliminate The electrostatic coupling signal from the circuit under test 50. In summary, the use of the current transformer 1〇〇 of the present invention through the isolation layer 16〇 can effectively reduce the generation of electrostatic coupling signals, and at the same time, the fabrication of the opening is used to avoid eddy currents. The effect of wear on the inductive product f. This design is especially beneficial for high and high frequency environments. However, it is possible to make the opening 162' in the isolation layer 160 to allow some of the electrostatic surface signals to penetrate the isolation layer 160. , the level coil 14 The current signal. Therefore, the present invention simultaneously uses a differential amplifying circuit 2 〇〇, with a circuit design of the intermediate winding 14 〇 in the middle of the ground (or grounding the contact of the two load resistors with the through-phase) to further exclude The present invention is described in detail by the preferred embodiments, and is not intended to limit the scope of the invention, and it is understood by those skilled in the art that 'There is no loss of the essence of the present invention, and does not depart from the spirit and scope of the present invention. [Simple description of the drawings] The first figure is a schematic diagram of the structure of a typical current comparator. The second figure is the flow of the first figure. Equivalent circuit diagram of the operation of the device. Third, the equivalent circuit diagram of the present gamma stream H - better _ The fourth diagram is the equivalent circuit diagram of the present invention than the stream II - better _ It is an equivalent circuit diagram of a further preferred embodiment of the present invention. The fifth figure is a schematic circle of the structure of the preferred embodiment of the present invention. The fifth embodiment is a schematic diagram of the internal structure of the current transformer of the fifth embodiment. The sixth picture - typical differential amplification Circuit diagram of the road. 1313357 [Description of main components] Conductor 10 Current transformer 20 Annular core 22 Secondary coil 24 Central hole 22a Current transformer 100 Annular core 120 Secondary coil 140 Isolation layer 160 Amplifier circuit 200 to be tested Circuit 50 output pin 150a, 150b opening 162 ground pin 190 load resistor 170, 170a, 170b 11