局部放电检测原理论述.pptVIP

* * Review of Lecture 5 1. Mechanisms of Dielectric Aging by PD 2. Process of Dielectric Aging by PD 3. The Influence Factors on Aging Rate 4. PD Evaluation Approaches Contents: Electrical aging is a type of dielectric deterioration under the long-term electrical field and due to the fact of partial discharges. Definition of Electrical Aging : Review of Lecture 5 Damage of internal discharge to polymer and oil-paper branched type brush type tree Review of Lecture 5 The Influence Factors on Aging Rate Electrical field stress Voltage frequency Situation of cavity and gas contents inside Temperature and humidity Mechanical force Review of Lecture 5 Estimation by the basic parameters (1) Apparent charge, qa (2) Discharge energy and power, W and P (3) The phase angle of pulses (4) Ui and Ue Estimation by the distribution (statistical) graphs Lecture 6 Principles of Electrical Discharge Detection 局部放电检测的基本原理 Contents 1. The Basic Diagram of ERA 2. The Detection Impedance 3. The Amplification of Impulses 4. Detection Sensitivity 5. Impulse Resolution 6. Calibration 脉冲电流法基本原理 检测阻抗 脉冲放大 检测灵敏度 脉冲分辨率 放电量标定 1. The Basic Diagram of ERA 1. A high-voltage source e, free of discharge. 2. A sample cx affected by discharges. 3. An impedance Zd 4. A coupling capacitance Ck 6. An amplifier A 7. An observation unit O 高压电源，无局放 试品 检测阻抗 耦合电容 放大器 观测单元 Δu 5. A protecting impedance Zm 保护阻抗，低通滤波 1. The Basic Diagram of ERA Two connecting methods (the location of Zd in circuit): 1. In series with the sample Cx- Series circuit. 2. In series with the coupling capacitor Ck- Parallel circuit. Series circuit Parallel circuit 串联回路 并联回路 2. The Detection Impedance Functions: (1) to transfer the impulse current into voltage and (2) to suppress the interferences of power frequency and harmonic from source. RC circuit RLC circuit 取得局部放电所产生的高频脉冲信号 抑制试验电压的工频及其谐波的低频信号 2.1 the RC circuit 2. The Detection Impedance Discharge extinguishes, Cd discharges via Rd Ct，Tuned capacitance调谐电容 Dampi