The **LEM HT 500-R** is a high-performance Current Transducer used for the electronic measurement of DC, AC, and pulsed currents with galvanic isolation between the primary circuit (high power) and the secondary circuit (electronic interface). --- ### 1. Key Technical Specifications The following table summarizes the primary electronic characteristics of the HT 500-R: | Parameter | Value / Description | | :--- | :--- | | **Primary Nominal Current ($I_{pn}$)** | 500 A | | **Measuring Range** | 0 to ± 500 A | | **Secondary Output Signal** | ± 4 V (at $I_{pn}$) | | **Supply Voltage ($V_c$)** | ± 12 V to ± 15 V (± 5%) | | **Accuracy** | ± 1% of $I_{pn}$ | | **Technology** | Hall Effect (Open Loop) | | **Frequency Bandwidth** | DC to 25 kHz | --- ### 2. Internal Electronic Components & Operation The HT 500-R operates based on the **Hall Effect principle**. Here is a breakdown of its electronic internal structure: #### A. The Magnetic Core The device features a circular or rectangular magnetic core that surrounds the primary conductor. This core concentrates the magnetic flux generated by the flowing current toward the Hall cell. #### B. The Hall Effect Generator This is a small semiconductor chip located in the "air gap" of the magnetic core. When current flows through the primary cable, it creates a magnetic field that exerts a force on the electrons in the Hall chip, creating a tiny voltage (Hall Voltage). #### C. Signal Conditioning Circuitry Because the raw Hall voltage is extremely small and sensitive to temperature, the internal PCB contains: * **Operational Amplifiers:** To boost the millivolt signal to the standard 4V output. * **Temperature Compensation:** Resistors and thermistors that ensure the sensor remains accurate even as the environment heats up. * **Voltage Regulators:** To stabilize the internal power supply from the ±12V/15V input. --- ### 3. Pinout and Connection The secondary electronic interface typically consists of a 4-pin connector: 1. **Pin 1 (+Vc):** Positive supply voltage (+12V to +15V). 2. **Pin 2 (-Vc):** Negative supply voltage (-12V to -15V). 3. **Pin 3 (Output):** The measurement signal (voltage proportional to current). 4. **Pin 4 (0V):** Ground/Common reference. --- ### 4. Electronic Advantages * **Galvanic Isolation:** There is no electrical connection between the 500A circuit and your microcontroller/PLC, protecting sensitive electronics. * **Low Power Consumption:** Very efficient secondary circuit. * **Linearity:** The output voltage maintains a straight-line relationship with the input current.