Balancing Thermal Performance With Other Desirable Cable Properties

Improving the thermal performance of a control cable can be a balancing act. Some of the changes to cable construction that widen the operating temperature range can compromise the cable’s electrical or mechanical properties. Silicone and cross-linked polyolefins do a good job striking that balance. Here’s why.

Wider Temperature Range

Both types of materials can dramatically widen the continuous use temperature range of control cables. A typical PVC control cable, for instance, can function in a temperature range of -40 to 90ºC. Compare that range to silicone-based cables, which work comfortably in a range of -50 to +180ºC.

The conductor material is also an important factor. For higher temperatures, a coated conductor is necessary to protect the bare copper effectively against corrosion. Tinned copper conductors should be used within a cable with a jacket made of silicone or cross-linked polyolefin.

Improved Wear And Chemical Resistance

With the most advanced cable technology, the additional thermal performance won’t affect the electrical properties of the cable at all, and any effects on mechanical properties will be minor or even advantageous. Compared to traditional PVC cables, the silicone and cross-linked polyolefin cables will exhibit:

●     Equivalent flexibility—though polyolefin cables are slightly stiffer than silicone or PVC cables

●     Improved wear resistance (for cross-linked polyolefin)

●     Improved chemical resistance

●     Equivalent flame performance

●     Halogen-free construction

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New White Paper Explores Cable Solutions For Extreme Temperatures

Control cables increasingly have to withstand temperature extremes in applications such as food and beverage machines, industrial ovens, furnaces, foundries and industrial process equipment. Extreme temperature applications can subject the cable to continuous-use temperatures as low as -50ºC and as high as 180ºC. For these environmental conditions, you have to think about cables with jacket materials other than PVC.

A Middle Ground

You could buy very expensive specialty cables that can withstand even hotter or colder temperatures, or you could try to use a more traditional PVC control cable, whose lifecycle starts to fall dramatically in hot or cold environments.

A growing class of control cables occupies a middle ground between over-engineered specialty cables and commodity PVC cables. Based on silicone or cross-linked polyolefin copolymers, these cables can take over in thermal environments that would cause PVC cables to fail prematurely. The trick is to choose a cable that balances thermal performance against other desirable cable properties.

Silicone Cables

Silicone cables are suitable for applications involving high temperature and a need for flexible wiring. They are also resistant to UV radiation, hydrolysis, oils, chemicals and plant and animal fats. For these reasons, they are commonly employed in metal processing applications, as well as in the industrial, automotive and automation industries because of their superior chemical resistance properties.

Polyolefin Cables

The second material alternative, crosslinked polyolefin, is formed from a combination of heat and high pressure—either by irradiating or chemically cross-linking the compound. These cables exhibit important electrical and mechanical properties that make them ideal for applications in electrical systems or heat treatment plants. These benefits include:

●     Increased thermal strength

●     Improved corrosion and abrasion resistance

●     Resistance to solvents, detergents and other operating fluids

●     Resistance to high temperatures

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BENEFITS OF PIN AND SLEEVE CONNECTORS OVER STANDARD TWIST LOCK

You’re likely familiar with twist lock cable connectors—they’re the National Electrical Manufacturers Association (NEMA) standard. However, there’s a lesser-known advanced cable connector that’s common in Europe, but has yet to find its place in the United States: the pin and sleeve connector.

In a nutshell, pin and sleeve connectors seal power connections and insulate power delivery from moisture, grime and chemicals. They’re designed to prevent disconnecting under load, and are often used for applications with abusive environments. Pin and sleeve devices range from metal-housed products to high impact-resistant plastic products with varying designs.

 

 

These male-female connections are well-suited for supplying power in a wide range of equipment such as welders, motor gen-sets, compressors, conveyors and portable tools and lighting. They’re also good for matching high-current power sources with the right equipment and integrate with switched and fused interlock receptacles in wet or corrosive environments.

Pin and sleeve connectors have plenty of other benefits that give them the edge over standard twist lock. Their rugged design provides heightened durability and a click-lock housing makes assembly fast and easy. Male plugs are surrounded by a shroud to protect the contact pins. These pins are exposed to the environment in most NEMA plugs.

In addition, pin and sleeve connectors have more configuration options than twist lock, and they’re color-coded for different amps—between 20 and 100 in the United States. NEMA twist lock sockets don’t have color coding.

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CHOOSE LOW SMOKE, HALOGEN-FREE CABLES FOR IMPROVED SAFETY

While halogen-free wires and cables have been widely used in Europe for some time, they’re now starting to gain traction in the United States. Products containing halogen—such as wires and cables, conduits, routing ducts and more—are receiving attention domestically due to the negative effects they impose on both industrial workers and machinery. And the push to reduce halogen usage is now reflected in UL and other domestic safety standards.

In the event of a fire, halogenated wires and cables give off toxic fumes that can cause serious health concerns if inhaled, not to mention they also destroy expensive electronic equipment. As industrial companies become more conscious of these problems, they’ve begun taking a closer look at the benefits of halogen-free cables.


Here’s a guide to some places where it makes sense to use halogen-free cables, and why you might want to consider them over halogenated cables in many applications.

A number of industry standards evaluate the cable fume toxicity produced during a fire. Each standard is unique because they approach the subject of determining cable fume toxicity through different evaluation parameters. They’re used to quantify smoke levels, light transmittance, levels of acid gas, concentration levels of toxic gases and halogen content.

While these standards are all different, they’re used to provide some determination concerning halogen-free or low smoke zero halogen cable requirements:

• IEC 60754-1: Details the amount of halogen acid gas measured from a specified amount of raw material. This test isn’t performed in the finished product wire or cable form, and compliance comes from not exceeding the mg/g that’s specified within the standard.

• IEC 60754-2: Shows the ph levels to determine the poisonousness of the gases during a fire. This standard approaches acidic levels that arise when halogenated components are burned and react with the moisture in the air.

• IEC 61034-2: Concerns the amount of light you can transmit while testing to determine the smoke density generated during a fire. High numbers show the effectiveness that a lighted pathway creates in a smoke-filled area.

• NES 713 Part 3: Determines the toxicity index of materials through complete combustion methods and analysis of the emitted gases. Measured in PPM, the gases must follow the highest values indicated, while concentration levels shouldn’t exceed the amounts for the 14 specified gases.

• UL 1685: This standard involves both the flame spread and fire resistance of cables, as well as methods for measuring smoke release. It establishes some pass/fail criteria, especially in the areas of peak and total smoke release. Lower numbers are desirable here, signifying the amount of smoke released.

• MIL-DTL-24643: Approaches the cumulative total contents of halogens in a cable by using X-ray fluorescence to determine amounts, giving an overall amount of concentration of halogen levels in a cable. Levels shouldn’t exceed the critical point of 0.2% under this standard specification for shipboard use.

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The basics of busway distribution systems

A distribution system is a system that distributes electrical power throughout a building. Distribution systems are used in every residential, commercial, and industrial building.…

Distribution Systems

A distribution system is a system that distributes electrical power throughout a building. Distribution systems are used in every residential, commercial, and industrial building.
Distribution systems used in commercial and industrial locations are complex.

A distribution system consists of metering devices to measure power consumption, main and branch disconnects, protective devices, switching devices to start and stop power flow, conductors, and transformers.

Power may be distributed through various switchboards, transformers, and panelboards. Good distribution systems don’t just happen. Careful engineering is required so that the distribution system safely and efficiently supplies adequate electric service to both present and possible future loads.

Feeders

A feeder is a set of conductors that originate at a main distribution center and supplies one or more secondary, or one or more branch circuit distribution centers. Three feeders are used in this example. The first feeder is used for various types of power equipment.
The second feeder supplies a group of 480 VAC motors. The third feeder is used for 120 volt lighting and receptacles.

Bus Bars

Commercial and industrial distribution systems use several methods to transport electrical energy. These methods may include heavy conductors run in trays or conduit. Once installed, cable and conduit assemblies are difficult to change. Power may also be distributed using bus bars in an enclosure. This is referred to as busway.

A bus bar is a conductor that serves as a common connection for two or more circuits. It is represented schematically by a straight line with a number of connections made to it. Standard bus bars in Siemens busway are made of aluminum or copper.

NEMA Definition

Busway is defined by the National Electrical Manufacturers Association (NEMA) as a prefabricated electrical distribution system consisting of bus bars in a protective enclosure, including straight lengths, fittings, devices, and accessories.
Busway includes bus bars, an insulating and/or support material, and a housing.

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5 key factors to the correct cable selection and application

Cable selection and application

It is essential to know cable construction, characteristics, and ratings to understand problems related to cable systems. However, to correctly select a cable system and assure its satisfactory operation, additional knowledge is required. This knowledge may consist of service conditions, type of load served, mode of operation and maintenance, and the like.

The key to the successful operation of a cable system is to select the most suitable cable for the application, make a correct installation, and perform the required maintenance.

In this technical article, discussion is based on the correct cable selection and application for power distribution and utilization.

Cable selection can be based upon the following five key factors:

1. Cable installation
2. Cable construction
3. Cable operation (voltage and current)
4. Cable size
5. Shielding requirements

1. Cable installation

Cables can be used for outdoor or indoor installations depending upon the distribution system and the load served.

A good understanding of local conditions, installation crews, and maintenance personnel is essential to assure that the selected cable system will operate satisfactorily! Many times cable insulation is damaged or weakened during installation by applying the incorrect pulling tensions.

Designs of conduit systems not only should minimize the number of conduit bends and distances between manholes but also should specify the pulling tensions.

The inspection personnel should ensure that installation crews do not exceed these values during installations. It is also important that correct bending radius be maintained in order to avoid unnecessary stress points. Once a correct installation is made, routine inspection, testing, and maintenance should be carried out on a regular basis to chart the gradual deterioration and upkeep of the cable system.

Cable systems are the arteries of the electric power distribution system and carry the energy required for the successful operation of a plant. Following is a brief discussion on cable installation and maintenance.

There are several types of cable systems available for carrying electrical energy in a given distribution system. The selection of a particular system may be influenced by local conditions, existing company policies, or past experience.

No set standards or established guidelines can be given for the selection of a particular system.

2. Cable construction

Selection and application of cable involves the type of cable construction needed for a particular installation. Cable construction involves conductors, cable arrangement, and insulation and finish covering.

2.1 Conductors

Conductor materials such as copper and aluminum should be given consideration with regard to workmanship, environmental conditions, and maintenance. The requirements for aluminum conductors with regard to these factors are more critical than for copper conductors.

Cable conductors should be selected based upon the class of stranding required for a particular installation.

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Control cables for high temperature applications from Lapp Group

As the lifeblood of your systems, cables and wires are vital to transmitting power and sending control signals and data in a timely and reliable manner. ÖLFLEX® HEAT cables are designed using the most reliable and rugged materials including cross-linked polymers, silicone, fluoropolymers
and fiberglass. These components ensure durable performance time and time again—providing optimum uptime and productivity.

Advantages of silicone cable

• Hydrolysis resistance
• UV resistance
• Resistant to oils, alcohols, plants and animal fats
• Withstands temperature as low as -50°C

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