The **KMS-C-R** series refers to a specific line of **Piezoelectric Force Transducers (Load Cells)** manufactured by Kistler. These sensors are designed for high-precision measurement of compression forces in industrial and laboratory environments. Below is a breakdown of the electronic and mechanical characteristics of the KMS-C-R series. --- ### 1. Core Operating Principle: Piezoelectric Effect Unlike strain gauge load cells that require an external excitation voltage to produce a signal, the KMS-C-R uses **Quartz Crystals**. * **Active Sensing:** When a mechanical force is applied, the quartz discs undergo deformation, generating an electrical charge ($pC$ - picocoulombs) proportional to the force. * **High Rigidity:** Because quartz is extremely stiff, the sensor has minimal displacement, allowing for high-frequency measurements. --- ### 2. Electronic Specifications The "R" in the series typically denotes a **Radial** cable exit or specific ruggedization for industrial use. | Feature | Specification | | :--- | :--- | | **Output Signal** | Charge ($pC$) | | **Sensitivity** | Approx. $-4.3$ to $-3.8$ $pC/N$ (varies by model) | | **Insulation Resistance** | $> 10^{13} \Omega$ (at 20°C) | | **Operating Temp Range** | $-20°C$ to $+120°C$ | | **Connector Type** | Usually KIAG 10-32 UNF or similar high-insulation connector | --- ### 3. Key Electronic Components & Integration To use a KMS-C-R sensor, a complete electronic measuring chain is required: #### A. The Sensor Body * **Quartz Discs:** The heart of the unit; usually cut in a specific orientation to respond only to compression. * **Internal Electrode:** Collects the charge generated by the crystals. * **Housing:** Stainless steel, hermetically sealed (IP65 or IP67) to prevent moisture from affecting the high-impedance insulation. #### B. The Signal Conditioner (Charge Amplifier) Since the output is a high-impedance charge signal, it cannot be read directly by a standard Voltmeter or PLC. You must use a **Charge Amplifier**: 1. **Conversion:** Converts $pC$ (Charge) into a low-impedance Voltage ($V$) or Current ($mA$). 2. **Scaling:** Allows the user to set the range (e.g., $1000 N = 10 V$). 3. **Reset/Measure:** Electronic switching to clear "drift" before a measurement cycle begins. #### C. Cabling * **Low-Noise Coaxial Cables:** Essential for piezoelectric sensors. Standard cables generate "triboelectric noise" when moved; the KMS-C-R requires specialized treated cables to maintain signal integrity. --- ### 4. Advantages & Use Cases * **Quasi-Static Measurement:** Can measure constant forces for short periods, but excels at rapid force changes. * **Wide Dynamic Range:** A single sensor can often measure very small forces and very large forces without changing hardware. * **Compact Integration:** Small form factor compared to hydraulic or strain-gauge alternatives. ---