How do you choose the right cable to ensure maximum performance and durability? In electric motors, insulation makes all the difference, and not all cables are the same.
When designing an electric motor and aiming for UL certification, one of the first elements to consider is the insulation system. This system is defined by Underwriters Laboratories Inc. (UL) and includes a list of compatible insulating materials that do not interact negatively. For connection wires, or lead wires, in Class B and Class F insulation systems, the choice often falls on XLPE (Cross-linked Polyethylene) and XLPO (Cross-linked Polyolefin) materials.
What Do XLPE and XLPO Mean?
- XLPE (Cross-linked Polyethylene) is a type of polyethylene that has undergone cross-linking through either a chemical process or irradiation, making it a part of the larger XLPO family.
- XLPO (Cross-linked Polyolefin) is the broader family of cross-linked polymers, which includes polyethylene. In other words, XLPE is a subset of XLPO.
When dealing with UL-certified cables, these acronyms identify the chemical family of the insulation material. For example, in UL insulation systems, you may find XLPO 150 °C or XLPE 150 °C listed, which include cables such as RADOX® UL 3289 and RADOX® UL 3680. For XLPE 125 °C, RADOX® UL 3266 is the right choice.
Excelling with Irradiation Cross-Linking
The term “XL” refers to polymer cross-linking. Without cross-linking, polyethylene chains can slide over each other, melting at relatively low temperatures. Cross-linking ensures greater chemical stability and resistance to high temperatures.
There are two primary cross-linking processes:
- Chemical cross-linking – This process is similar to rubber vulcanization. An activator is added to the compound, and a special “baking” process triggers the chemical reaction that creates bonds between polymer chains.
- Irradiation cross-linking – In this process, after the insulation extrusion, the cable is bombarded with beta rays (high-energy electrons) inside shielded bunkers. This process achieves a higher degree of cross-linking, significantly improving thermal and mechanical performance. However, it requires a greater investment in both machinery (a beta-ray generator) and energy consumption. This method is considered the gold standard in cable insulation systems.
RADOX® compounds utilize irradiation cross-linking, offering superior performance compared to other market products that rely on chemical cross-linking.
You can learn more about this topic with our article on how the cross-linking process occurs by irradiation.
Key Technical Properties and Performance in Critical Conditions
XLPE and XLPO cables are recommended for use in electric motors or generators with insulation class up to Class F (150 °C). Thanks to irradiation cross-linking, RADOX® cables can withstand temperatures up to 250 °C for short periods.
The key advantages of irradiation cross-linked XLPE/XLPO cables include:
- Enhanced thermal resistance – The molecular network prevents the insulation from melting at high temperatures.
- Superior dimensional stability – Maintains mechanical and insulating properties even in extreme conditions.
- High chemical resistance (RADOX® UL 3680) – Suitable for challenging environments involving oils, fuels, or corrosive agents.
Comparing Cross-Linking Methods: Cost, Durability, and Maintenance
Different cross-linking methods have their own strengths and drawbacks:
- Chemical cross-linking – This method is more cost-effective in terms of production but provides lower thermal and mechanical performance. It is suitable for less demanding applications but has a shorter lifespan and may require additional precautions in environments with frequent thermal and vibrational stress.
- Irradiation cross-linking – This method requires a significant investment in technology and higher energy consumption, making the cables more expensive. However, irradiation cross-linked cables, such as RADOX® cables, generally have superior durability in harsh environments, including exposure to high temperatures and chemicals.
Miotti as a Global Distribution Hub
As a Global Distribution Hub for RADOX® cables, we ensure efficient and reliable service with a huge stock inventory and delivery within one week. Learn more about RADOX® solutions and our range of specialized cables by visiting our website or contacting us for a free consultation.
A Reliable and Durable Choice
Choosing between XLPE (Cross-linked Polyethylene) and XLPO (Cross-linked Polyolefin) is not just about acronyms but about thermal, mechanical, and cost performance. If you are designing a UL-certified electric motor and want to maximize durability and reliability, an irradiation cross-linked XLPE/XLPO cable like RADOX® is the best choice.