万博集团仪器设备站 · 专业测试测量仪器授权供应商
讲解 LCR 表如何由 Z 与 θ 计算 L/C/R，串/并联等效电路的选择，以及开路/短路补偿与测试信号电平。
中文概述：本文为 LCR 表使用基础，介绍阻抗复数表示、串联/并联等效电路的适用对象、开路与短路补偿原理，以及开路电压/恒压/恒流三种测试信号模式。正文为英文原文。
The impedance Z consists of a real part (Rs) and an imaginary part (X): Z = Rs + jX, |Z| = √(Rs²+X²), θ = tan⁻¹(X/Rs). LCR meters measure the current through the target and the voltage across its terminals to derive Z and θ, then calculate L, C, and R.
The instrument cannot determine the right mode itself. Series mode (Cs/Ls in series with Rs) suits low-impedance elements (~100 Ω or less), such as large capacitors and low inductances. Parallel mode (Cp/Lp in parallel with Rp) suits high-impedance elements (~10 kΩ or more), such as small capacitors and high inductances.
The fixture has residual components, so the measured value Zm contains residual impedance and admittance. Open correction and short correction remove these residual components to yield the true value Zx; LCR meters include both functions.
The output is divided between the instrument's output impedance and Zx. Three modes exist: open-voltage (V) mode sets the open-terminal voltage; constant-voltage (CV) mode sets Vx across the target (used for voltage-dependent devices like high-k MLCCs); constant-current (CC) mode holds a fixed current.
