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1. Introduction to SRPS N.C5.350 Standard 

**SRPS** refers to the **Serbian Standardization System**. It represents **national standards** developed under the jurisdiction of the **Institute for Standardization of Serbia (ISS)**. 
- **N.C5.350** appears to be a standard concerning **electrical cables**, likely specifying technical, mechanical, and performance requirements. 
- Such standards are aligned with international norms, including **IEC (International Electrotechnical Commission)** and **EN (European Norms)**.

Purpose: 
The SRPS N.C5.350 ensures electrical products like cables conform to safety, performance, and operational requirements. This is particularly critical for applications in infrastructure, industrial, or residential power systems.

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2. Type EpN 50: Meaning and Classification 

**Type EpN 50** likely refers to a specific **cable type** or **conductor designation** defined under the SRPS standard. Let's break it down:

EpN: 
- "Ep" may refer to **EPR (Ethylene Propylene Rubber) insulation**, a common material in high-flexibility, temperature-resistant cables. 
- "N" may denote **neutral/nominal** applications or specific characteristics like low-voltage conductors.

50: 
- Refers to the cable's **cross-sectional area** in square millimeters (**mm²**), commonly used for electrical conductors.

Technical Characteristics of EpN 50 Cables: 
1. **Conductor Material:** 
   Typically made of **annealed copper** or **aluminum** for high conductivity.

2. **Insulation Material:** 
   EPR (Ethylene Propylene Rubber): Known for: 
   - High thermal resistance (operates at up to 90°C continuously). 
   - Superior flexibility and durability. 
   - Resistance to **moisture, oils, UV radiation**, and chemicals.

3. **Voltage Rating:** 
   Typically for **low-voltage (LV)** or **medium-voltage (MV)** applications (e.g., 0.6/1 kV or 6/10 kV). 

4. **Outer Sheath:** 
   Protected by robust sheathing material such as **thermoplastic PVC** or **elastomeric compounds** for mechanical durability.

5. **Cross-sectional Area – 50 mm²:** 
   - This large conductor size indicates that the cable can handle **higher currents** with low voltage drop. 
   - Suitable for power distribution systems, substations, and industrial machinery.

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3. Applications of Type EpN 50 Cables 

The **EpN 50 cables** are used in applications requiring: 

• High Current Capacity: Industrial power supply, substations, or heavy-duty cable installations.
• Flexibility: EPR-insulated cables are ideal for dynamic environments with frequent movement.
• Durability: Resistance to extreme temperatures, mechanical wear, and harsh chemicals.
• Moisture Resistance: Suitable for underground or outdoor installations, where exposure to moisture is likely.

Example in Cable Manufacturing: 
- **Substation Power Transmission:** EpN 50 cables are used to connect transformers to switchgear panels. 
- **Industrial Plants:** Power supply for heavy machinery requiring high amperage. 
- **Renewable Energy Projects:** Used in solar or wind installations to distribute power efficiently. 

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4. Key Advantages of EpN 50 Cables 

1. Thermal Resistance: 
   - With EPR insulation, cables can operate reliably at temperatures up to **90°C** under normal conditions and up to **130°C** during short circuits. 

2. Electrical Conductivity: 
   - 50 mm² conductors allow low resistance, ensuring **minimal power losses** over long distances. 

3. Durability and Flexibility: 
   - EPR insulation gives exceptional flexibility, which is essential for installation in tight spaces or dynamic environments. 

4. Environmental Resistance: 
   - Resistant to UV rays, water, and chemicals, making it ideal for **outdoor applications**.

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5. Standards Compliance and Testing 

Type EpN 50 cables must comply with the following testing requirements: 

1. Electrical Testing: 
- Insulation resistance test (Megger test). 
- High-voltage withstand test to verify insulation integrity. 

2. Mechanical Testing: 
- Tensile strength and elongation testing for conductor materials. 
- Flexibility tests to ensure the cable bends without damage. 

3. Environmental Testing: 
- Aging resistance under high temperatures. 
- Water absorption tests for moisture resistance. 

Relevant Standards: 
- **IEC 60502:** Power cables with extruded insulation. 
- **SRPS N.C5.350:** Serbian standard for low-voltage and medium-voltage cables. 

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6. Conclusion 

**SRPS N.C5.350** specifies the technical requirements for cables, ensuring **safety**, **reliability**, and **performance**. **Type EpN 50** refers to an EPR-insulated cable with a 50 mm² conductor, designed for high-performance applications in **power distribution, industrial plants**, and **renewable energy projects**.

Key Takeaway: 
Type EpN 50 cables offer superior flexibility, thermal resistance, and electrical performance, making them ideal for demanding power transmission and distribution applications.

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