2023/01/28

【低壓電容補償櫃】低壓電容補償櫃測試(T&C of LV Capacitor Bank)- 出廠驗收測試(FAT)

一般來說,低壓電容補償櫃由櫃殼/櫃體、匯流排、斷路器、隔離開關,繼電器、接觸器、電容器、電抗器、一/二次導線、端子排、功率因數自動補償控制裝置、盤面儀表等組成。


電容器補償櫃的作用

電容補償櫃的作用是提高負載功率因數,降低無功功率,提高供電設備的效率;電容櫃是否正常工作可通過功率因數表的讀數判斷(可獨立於櫃面,或者可在功率補償控制器上查看),功率因數一般要求在0.9。


基本元件及其結構





出廠驗收測試(FAT)的主要步驟

1. Visual check (外觀及內部元件檢查)

   Purpose of Test: To check the general construction of the capacitor bank.

   Procedure:

(1) Record the capacitor bank model, serial number and parameters on the attached test form.

(2) Visual inspection for the following items:

    • General appearance inspection.
    • Colour of FBA in accordance with the drawing.
    • The layout of all circuits is in accordance with the drawing.
    • Dimension, clearance and creepage of busbars and risers.
    • Tightness of all screws, bolts and nuts by random check.
    • Complete earthing system.
    • All Main Switches, Fuse Carriers and Controllers operate correctly and freely by hand.
    • Mains cables are phase coloured correctly.
    • Control wirings and ferrules are connected correctly.
    • Capacitor Controllers, Static Switches, Detuned Reactors, Capacitors model, connection and location in accordance with the drawing.
    • Label for circuit identification.
    • Capacitor Bank Cleaning.
    • Check the controller setting.

        (3) Record the result on the test form.


2. Insulation Resistance Test for Main Switchgear & Busbar Chamber / Megger Test (絕緣電阻測試)

   Purpose of Test: To check the insulation of the main switchgear & busbar chamber.

   Procedure:

(1) Check the busbars under test are connected correctly in accordance with the drawing.

(2) Turn off the main switch and all control fuses shall be withdrawed.

(3) Connect the 1000V direct current insulation tester to phase L1 and earth. After each test discharge and earth busbars before disconnection. Check the insulation resistance and record on the approved test form.

(4) Repeat this test on phase to phase, phase to neutral and neutral to earth. The insulation resistance should not be less than 1 MΩ.

(5) Record the result on the test form.


3. Capacitor Bank Charging & Discharging Test and Auto Mode Simulation Test (電容器充放電測試及功率補償控制器自動控制測試)

   Purpose of Test: To check if the capacitor bank charging and discharging normally.

   Procedure:

Manual mode test of the capacitor step switch in/ Out by pressing the “<>” button at the power factor regular

(1) Close the fuse holders feeding the first stage capacitor & provide the minimum current for the P.F. controller.

(2) Press the “<>” button, the first stage capacitor step will switch in instantaneously and the corresponding step indicator in the PFR will come on

(3) Measure the capacitor terminal voltage and current and record the result on the test form

(4) Press the “<>” button, the first stage capacitor step will switch out instantaneously and the corresponding step indicator in the PFR will go out

(5) Open the first stage fuse holder feeding the switched capacitor step, 60 seconds then measure the discharged capacitor terminal voltage and enter the data into the test form

(6) Press “+” or “-“ button to repeat the above procedure for the remaining stage until all stages are tested ( Remark : only one set can be tested at a time.)


Auto mode simulation test of the capacitor step switch In / Out for Power Factor Regulator only

(7) Inject current to Power Factor Regulator to simulate the power factor value, for example, input a current to make the P.F. as 0.89 (any value smaller than 0.90 ) inductive load and the set target P.F. to 0.90 inductive load, the regulator will auto switch in the step of capacitor bank from step 1 to step 6 to make the target P.F. and then change the current flow direction to simulate the over compensation of P.F. and the P.F. will be changed to 0.89 capacitive load from inductive load, and the capacitor bank will be switch out from step 1 to step 6. 

(8) The simulation test of auto mode is completed and record result on the test form


4. Ventilation Fan Function Test (散熱風扇功能測試)

   Purpose of Test: To check the function of the ventilation fan.

   Procedure:

(1) Turn the ventilation fan mode selector into Manual position, the ventilation fan will be turn on permanently.

(2) Turn the Ventilation Fan mode selector into OFF position, the ventilation fan will be turn off permanently.

(3) Turn the ventilation fan mode selector into Auto mode, the ventilation fan will be controlled by the thermostat controller.

(4) Record the result on the test form.



2023/01/11

【高壓制櫃設計】 - 高壓掣櫃之設備(三)- HV Protection Device 高壓保護裝置

Pilot Wire Differential Protection 差動保護

差動保護是高壓線路、發電機、變壓器的主要保護。是在被保護對象的兩端安裝電流互感器(C.T.),利用電流互感器里采集的電流進行比較,計算差值。如果差值超出定值,再滿足電壓的閉鎖條件,一般是電壓降低,因為發生相間短路或者接地的時候,電流會升高,所以電壓就會降低。當電壓降低到一定程度,電流高於定值的時候,保護動作啟動開關跳脫。

差動環流保護原理可應用於饋線保護。在每條受保護線路中連接兩個 CT,每端一個。在無故障條件下,兩端 CT 的次級電流相等,並且該電流在引導線中循環。在無故障情況下,兩個 CT 的差動電流 I1-I2 為零,繼電器不動作。一旦饋線產生故障,這種平衡被打破,差動電流流過繼電器操線圈。電流流過控制線和繼電器。線路兩端的斷路器跳閘,隔離故障線路。

差動保護單線示意圖


差動保護三相接線示意圖

測量兩段電流互感器的精確匹配是非常重要的。如果Pilot Wire出現斷路,系統將無法提供保護。如果保護的線路較長,由於需要較長的Pilot Wire,整個系統成本較高,而且,在Pilot Wire較長的情況下,由於Pilot Wire的電容效應的充電電流甚至在正常情況下也足以導致保護動作啟動開關跳脫。

某差動保護元件及型號:Link




饋線差動保護產品說明