1. Product Overview: MD7LC Surge Protector

️· Purpose: Designed to protect strain gauges and related devices from voltage surges.
️· Manufacturer: M-System (as evident from the website URLs in the specifications).
️· Models: MD7LC-0 and MD7LC-1. The "-0" and "-1" likely refer to different surge suppression capabilities/configurations (more on this in the Safety Parameters section).

2. Technical Specifications (Highlights)

️· Voltage: Details on specific voltage ratings will be found within the 'Safety Parameters' section below.
️· Series Resistance: (Important for categorization – see EN 61643-21 below).
️· Surge Current Capability: Not explicitly stated, but implied to be suitable for strain gauges.
️· Mounting: Designed for DIN rail mounting.
️· Connections: Connections labeled G (Ground), EXC (Excitation), and OUTPUT.
️· Dimensions: (Refer to the diagram on page 3/4 - units in mm)
- 8-M3 Euro Terminal.
- Wire Insertion Angle: Approx. 20°
- 98mm x 3.86 (likely width and depth)

3. Connection Examples (Refer to Page 3/4)

️· Diagrams illustrate different connection schemes involving:
- Ground (G)
- Excitation (EXC)
- Output
- Use of MD7G (likely a separate component for grounding, a "grounding adapter" of some sort)
️· Important Note: Without the MD7G, the diagram indicates a cross-wire connection may be necessary.

4. Safety Parameters (Crucial for Correct Usage)

️· Temperature Class: The most critical parameter for ATEX/IECEx compliance.
- T4: When operating within this temperature class, the MD7LC can be used within the following ranges:
■ -25°C to +40°C: 1.3W power dissipation.
■ -25°C to +60°C: 1.2W power dissipation.
■ -25°C to +80°C: 1.0W power dissipation.
- T5:
■ -25°C to +40°C: 1.0W power dissipation
️· ATEX/IECEx Data (for T4 and T5 temperature classes):
- Ui (Vmax): 16V (Maximum Voltage)
- Ii (Imax): Any (Current)
- Ci: 35 nF (Capacitance)
- Li: 0 µH (Inductance)
- Pi: Temperature class, range and power parameter data.
️· Model-Specific Differences (MD7LC-0 vs. MD7LC-1): These are *not* explicitly defined in this document. However, given the safety parameters that include temperature classes and wattage, it's very likely that the differences relate to the level of surge protection and the allowed operating temperature range to meet those ATEX/IECEx requirements.

5. Standards & Categorization

️· EN 61643-21: (Surge Protective Devices – Requirements for Protection against Surge) – Applies to this device. Important for determining protection category. The series resistance of the device is a key factor in the categorization.
️· ATEX/IECEx: Designed and certified for use in potentially explosive atmospheres (refer to safety parameter section).
️· Categories: C1, C2, D1 (According to EN 61643-21).

6. Important Considerations and Cautions

️· Grounding: Proper grounding is *essential* for safety and optimal performance. The MD7G adapter may be required in some connection scenarios.
️· Temperature Rating: *Strictly* adhere to the temperature class ratings (T4 or T5) and operating temperature ranges. Exceeding these limits could compromise safety and void certifications.
️· Power Dissipation: The wattage (Pi) given in the safety parameters must be considered when installing – the device may need ventilation to avoid overheating.
️· Series Resistance: The specification of the series resistance is important in ensuring that correct categorization of the surge protective device is carried out, and that appropriate applications are selected.