How to Select a Servo Cable for a Motor? The most important aspects

Frequency converters play a crucial role in various industrial applications, particularly in pump control systems and other machinery requiring precise speed regulation of AC motors. However, to ensure that inverters operate efficiently and without failure, it is essential to select a servo cable that is fully compatible with the motor it connects to.

In this article, we will explore the key factors to consider when choosing cables for these devices, the importance of using the correct cable glands and locking nuts, and which cables available on the market are best suited for outdoor use or environments requiring high fire resistance.

What parameters should be considered when selecting a servo cable for a motor?

The most important parameter to consider when choosing a servo cable is the motor power. As power increases, it becomes necessary to use cables with larger cross-sections and higher current-carrying capacity. For low-power devices up to 15 kW, four-core cables with a cross-section of 1.5 mm² are sufficient, supporting a current-carrying capacity of 23A at 30°C and 16A at 55°C. In contrast, motors rated at 90 kW require cables with cross-sections of 16 mm² or 35 mm².

Additionally, it is important to avoid using single-shielded cables, as they do not provide sufficient electromagnetic compatibility (EMC). The most widely recommended solution today is double-shielded servo cables, which feature one shield made of aluminum and another made of copper braid. This dual shielding effectively minimizes unwanted signals across various frequencies and helps maintain a low level of electromagnetic interference (EMI) within the inverter-cable-motor system.

Insulation and Grounding of Servo Cables for AC Motors

Choosing the right insulation is essential when selecting cables to connect an inverter to an AC motor. Important factors to consider include voltage resistance and the rate of voltage rise (dv/dt). Cross-linked polyethylene (XLPE) insulation is highly recommended due to its ability to support a higher current-carrying capacity while maintaining a relatively low insulation capacitance compared to other materials.

Using a cable with insufficient insulation resistance or high capacitance can lead to serious issues, potentially resulting in irreversible motor damage. Therefore, it is crucial to ensure that the selected cable provides adequate protection against hazardous breakdowns before making a purchase

Choosing Motor Connection Cables for Specific Environmental Conditions

Regardless of the application, modern BiTservo cables are available in various types and provide an excellent solution. They all offer strong resistance to the environmental conditions typically found in industrial settings. These cables feature special self-extinguishing sheath and comply with EMC compatibility standards.

The flexible BiTservo 2XSLCY-J cables are ideal for both fixed and dynamic connections, performing well in machinery located in both dry and humid environments. For motor connections requiring cables to be buried directly in the ground, the BiTservo UV 2XSLCYK-J FR model is the recommended choice.

Specialized Servo Cable Models for Specific Applications

• Fire-Risk Areas: In locations where fire hazards are a concern, it is best to use cables with a flame-retardant sheath and an oxygen index above 29%. Recommended options include BiTservo UV 3plus 2XSLCYK-J FR and BiTservo UV 2XSLCYK-J FR.
• Oil-Exposed Areas: For environments prone to industrial oil exposure, BiTservo MV6 and MV10 cables with EPR rubber insulation provide excellent electrical properties.
• Halogen-Free Cables: In cases where non-halogenated materials are required to prevent corrosive gas emissions during a fire, the suggested cables are BiTservo 2XSLCH-J, BiTservo 3plus 2XSLCH-J, BiTservo UV 2XSLCHK-J, and BiTservo UV 3plus 2XSLCHK-J.
• Outdoor and UV-Resistant Cables: For outdoor use, it is advisable to select cables that can withstand UV radiation, such as UV 3plus 2XSLCYK-J FR and BiTservo UV 2XSLCHK-J, along with their symmetric 3plus counterparts.

Why is Choosing the Right Cable Glands for Servo Motor Cables Important?

Cable glands serve a crucial function as the connection point between device housings and cables, ensuring safe operation and extending the lifespan of inverters. Modern cable glands effectively protect the cable entry point and prevent mechanical damage, such as twisting or pulling. These components are essential in all installations requiring full electromagnetic compatibility (EMC).

All the servo cables for industrial motors mentioned above are available from BITNER Cable Factory. We encourage you to explore our complete product range!

If you have any questions, please don’t hesitate to contact us via email at: wsparcie.techniczne@bitner.com.pl