ÖLFLEX® & UNITRONIC® Cables
Q. Why don't all our ÖLFLEX® and UNITRONIC® cables have a CE mark?
A: The CE mark refers to the European Parliament's Low Voltage Directive 2006/95/EC and applies to cables and wires designed specifically for voltages between 50 and 1000 V (alternating current) or 75 and 1500 V (direct current) – i.e. voltage classes U0/U 100/100 V, 300/500 V, 450/750 V and 600/1000 V). Network data cables < 50 V as well as connecting cables exceeding 1000 V (e.g. voltage class Uo/U 1.8/3 kV or 3.6/6 kV) are not subject to the Low Voltage Directive 2006/95/EC and therefore, do not feature the CE mark on the outer sheath or packaging label.
Q. Are ÖLFLEX® and UNITRONIC® cables suitable for direct burial?
A: To be used underground without additional protection, cables must meet the relevant standards (as in the case of NYY cable) or at least fulfil specific constructional design requirements for this installation. The outer jacket of cables that is laid underground without extra protection must be reinforced and of a sufficient strength and resistant to both mechanical impact and hydrolysis. The minimum outer sheath thickness for direct burial depends on the cable dimension, but should not be less than 1.8 mm. As far as possible; cables that meet these requirements should still be embedded in sand or covered by a protective covering to offer mechanical protection from rubble and stones. Generally speaking, all cables are suitable for direct burial, provided that they are enclosed in suitable protective tubes and pipes and are adequately resistant to hydrolysis.
Q. Can we confirm the number of bending cycles of various ÖLFLEX® FD and UNITRONIC® FD versions suitable for drag chain use if queried by customers?
A: It goes without saying that all products in our ÖLFLEX® FD and UNITRONIC® FD ranges designated as suitable for drag chain use have been thoroughly tested in our drag chain centre during development. However, due to the wide range of cable dimensions as well as the limited test chain capacity and the relatively long test duration, it is not possible to perform separate tests for each individual product article.
In many cases, conducting drag chain tests until such time that the cable is damaged or destroyed is neither possible nor expedient, since a large number of cables would require several million bending cycles and would thus spend many years in the test centre before they eventually fail. We subject our FD cables to at least five million bending cycles under the strictest test conditions.
This means that cables listed in the catalogue and data sheet with a flexible bending radius of, for example, 7.5 x cable diameter have actually only been tested with a test chain radius of 5 x cable diameter. Our extensive experience in this area has shown that cables reaching five million cycles can easily accomplish significantly higher cycle numbers without encountering problems. In some cases, cables have been removed from the test chain without significant damage after 11 million bending cycles, simply to make room for new test cables.
Depending on individual travel and speeds, our test chains complete between 5000 and 20,000 cycles per day. Even if test logs detailing the exact number of bending cycles exist for the inspected cable dimension, these cannot be made available to customers or third parties.
If a customer contacts you to obtain confirmation on bending cycle numbers for a specific product, you can request a customer letter from the product manager responsible for ÖLFLEX® FD and UNITRONIC® FD cables. This letter provides general information on the suitability of all ÖLFLEX® FD and UNITRONIC® FD cables for at least five million bending cycles as well as details on test conditions and parameters.
Please find attached a statement from the UIL Product Management regarding the service life of our FD cables.
Service life and test conditions of FD cables-02.2013.pdf
Q. When is an ÖLFLEX® or UNITRONIC® cable deemed "low-capacitance" and what advantages does this offer over other cables?
A: The capacitance (C) of a component – in this case a cable – represents its ability to store electrical energy. A cable with low capacitance can be used over longer distances and offers lower transmission losses than a standard cable of the same length. Whether or not a cable qualifies as "low-capacitance" depends on the insulation material that is used. In the field of data network cables, pure air would be one of the best and thus also one of the lowest capacity insulation materials.
However, since it is technically impossible to use air as core insulation and to strand the bare copper conductors without contact, a range of different plastics are used for insulation purposes. Air has a dielectric constant of 1. Similarly, all insulation plastics used in cable technology also have a specific dielectric constant, which is measured at a specified frequency and ambient temperature. The dielectric constant indicates the factor by which the capacitance increases when air is replaced with a different insulation material such as polyvinyl chloride (PVC) or polyethylene (PE).
The higher the dielectric constant, the greater the capacity. The lower the constant, the better suited the material is to electrical core insulation. Compared to other insulation materials, PE for instance has a very low dielectric constant of approx. 2.2, which is why it is used for higher quality products such as LAN, BUS or coaxial cables. In some cases, small air bubbles or foam are encapsulated in the PE insulation to further improve the transfer quality. Depending on its composition, PVC takes up a mid-table position with values between 3.5 and 7. With dielectric constants of up to 9.0, elastomers such as chloroprene rubber are at the bottom of the pile when it comes to insulation materials for data network cables; even when used for connecting or control cables, relatively thick insulation wall thickness of such materials are required to achieve satisfactory insulation performance.
Symmetrical core stranding can also have a positive effect on the capacitance (e.g. ÖLFLEX® SERVO 9YSLCY-JB with its three-part, green/yellow protective earth conductor). A cable can be described as "low-capacitance" if the mutual capacitance specified in the catalogue for a PE-insulated cable, for example, is approx. half that of a cable which merely has PVC insulation, for instance.
Q. Where can I obtain information on the chemical resistance of ÖLFLEX® and UNITRONIC® cables?
A: The resistance of our cable products to specific organic and inorganic chemicals is already detailed in table T1 of our technical catalogue appendix. If the required substance is not contained in this table, it is possible to contact our laboratory in Stuttgart to enquire whether any data or information concerning resistance to this chemical medium exists in the relevant technical literature. Statements regarding the resistance of our cables to specific branded products, such like for instance “Exxon Mobile XY or Castrol XY transmission fluid”, are not generally possible since these constitute unknown mixtures of different oils and additives.
In the case of commercially attractive projects, the laboratory may agree to test our cable products with the specific chemical substances (usually oils) used in the customer's application. The customer would have to supply one liter of the relevant substance along with the corresponding safety data sheets. However, we reserve the right to refuse any chemicals that present even the slightest safety risk to our lab personnel. For this reason, the general test scope and schedule should be agreed with the laboratory in advance. The resistance tests are generally performed in accordance with the relevant VDE, EN, IEC or UL test methods.
Q. What is the difference between ÖLFLEX® or UNITRONIC® cables certified as "UL AWM recognized" and those that are "UL-listed"?
A: If the manufacturer of an electrical device, appliance or machine wishes to obtain an officially approved "UL listing" to release the relevant item as a series product or acquire a "field labelling" for a stand-alone machine or system, the US body tasked with the certification (the National Recognized Testing Laboratory or NRTL) must be provided with all construction-relevant documentation. The entire certification process will be significantly faster, simpler and cheaper if all cables and wires used in the product are already "UL-listed" or at least "UL-recognized". Any cables without UL certification must first be subjected to protracted testing in the UL laboratory.
All machine exporters are therefore advised to employ UL-certified cables and wires as a matter of course. UL AWM recognized cables with AWM style numbers, e.g. ÖLFLEX® 150 QUATTRO: Appliance wiring material or better known as "AWM" comprises cables and wires intended solely for use in factory-wired electrical equipment, devices, appliances, control cabinets and industrial machinery as part of a "listed assembly". AWM is not intended for on-site or field wiring purposes. Cables and wires with UL AWM Style labelling must be used for the applications stipulated by the relevant style designation. The use of AWM-recognized cables and wires is restricted to the applications detailed in the corresponding style specification (www.ul.com). AWM styles are not part of the North American NEC (National Electrical Code).
Following the introduction of the 2007 edition of the NFPA 79 standard, the use of UL AWM recognized cables in industrial machinery and systems can be very problematic in terms of the machine certification, as the installation of AWM cables in this environment is only permitted under strict observance of specific conditions. "UL-listed" cables, e.g. ÖLFLEX® CONTROL TM: The intended use of cables and wires in this category is for fixed wiring in residential buildings as well as for commercial and industrial use.
UL-listed cables and wires not only have to meet individual UL product standards, but must also comply with the relevant paragraphs of the National Electrical Code (NEC). The NEC contains detailed specifications relating to the correct usage of listed cables and wires. Such products can be used both for factory wiring of electrical equipment, devices, appliances and machines as well as for on-site or field wiring of industrial machinery and systems according to NFPA 79.
Q. Are ÖLFLEX® and UNITRONIC® cables suitable for drag chain use even if they were not specifically constructed and tested for permanent flexible application?
A: Even though some customers have successfully employed standard ÖLFLEX® cables in drag chain applications, despite their not being developed for permanent flexible use in energy supply chains, we are unable to recommend such practices as no corresponding experience or test data exists. In our test centers, we only assess the suitability of ÖLFLEX® and UNITRONIC® cables with the designation "FD", which were developed specifically for such highly flexible applications. It is entirely at the customer's discretion to employ cables for unintended purposes. Eg: as drag chain cables.
Q. Which ÖLFLEX® and UNITRONIC® cables are suitable for use in technical vacuum applications?
A: Vacuum technology is particularly prevalent in the coating industry, where it is used for a large number of products. Vacuums enable the application of very thin layers to the relevant product, while preventing oxidation and contamination. Today, products such as compact discs, eyeglass lenses, precision optical components, mobile telephones, tools, semiconductors and even flat screens are coated under vacuum conditions. In vacuum coating systems, it is often necessary to pass cables through the vacuum, e.g. to contact light sensors.
In many cases, the evaporation produced in the negative vacuum pressure results in increased ambient temperatures, which further limits the potential cable selection. The size of the occurring negative pressure is also relevant. Many insulation and outer jacket materials already emit substances, such as plasticizers, at normal atmospheric conditions and this process is both facilitated and accelerated by the negative pressure in a vacuum.
As a result, cables can harden and brittle prematurely, while the emitted substances can contaminate the entire vacuum. Due to their relatively high gas emission, plastics such as PVC, chloroprene rubber and silicone in particular are less suitable for vacuum applications. Although we have limited experience and test data with regard to vacuum applications, we would recommend the use of fluoropolymer cables made of PTFE, such as the ÖLFLEX® HEAT 260, due to their wide temperature range and very low gas emission. Plastics such as PEEK (polyetheretherketone), PI (polyimide) and PA (polyamide) are also well suited to vacuum applications, but these materials are very stiff and quite expensive, making them unsuitable for use for standard cables.
Q. Where can I obtain an UL certificate for an ÖLFLEX® or UNITRONIC® cable?
A: There are no separate UL certificates for ÖLFLEX® and UNITRONIC® cables detailing, for example, the product name and a description, as in the case of GL (Germanischer Lloyd) certificates for instance. Whether or not a cable is legitimately UL-certified is indicated by the normative element of the cable imprint. It must contain all UL AWM styles or UL listings for which the cable has been tested and certified. The UL file number (e.g. E63634 for U.I. Lapp), a code for the manufacturer or certificate owner, is usually found at the end of the cable imprint. A public UL database is available on the Internet at www.ul.com. By selecting "Certifications" and entering the file number in the relevant field, anybody can check whether the relevant cable manufacturer is certified by the UL authority and thus authorised to print an UL AWM style or UL listing on their products. This website can be used to search by file number or company name. Some 1000 available UL AWM styles (Appliance Wiring Material) are listed under the U.I. Lapp file number E63634 alone.
UL-recognised and UL-listed cables are subject to very strict production controls. Manufacturers cannot simply produce cables with incorrect UL imprints and without the correct authorisation or bring such products to market. The productions plants are periodically audited by UL inspectors, who check the accuracy of the imprint on UL-certified cables and take production samples for subsequent examination in the UL laboratory. With the UL labelling system, each drum of UL-certified cable is registered using special, sequentially numbered UL label stickers. These measures ensure that manufacturers only produce UL-imprinted cables for which they have UL authorisation and have paid the necessary certification fees.
If a customer requires a UL "certificate" for a specific ÖLFLEX® or UNITRONIC® cable, he can visit the aforementioned website and use the relevant file number to check the validity of the UL AWM styles or UL listings printed on the core insulation or cable outer sheath.
Q. What do I do if a customer requests the ampacity of an ÖLFLEX® cable and asks for the ideal conductor cross-section for his application?
A: As a cable and wire manufacturer, we are not generally permitted to calculate the ampacity of cables for the planning or operation of electrical equipment, plants and systems. Such calculations usually involve many different factors, of which neither we nor – as is often the case – the customer are aware. If incorrect planning results in the selection of the wrong conductor cross-section, which in turn leads to faults, fire damage or personal injury during later operation of the machine or system, the party who conducted the planning will be held responsible! This is why a number of engineering consultancies make their living by planning electrical plants and systems.
The following are just some of the important factors required to ensure accurate and, most importantly, safe determination of the right conductor cross-section:
- What power level is to be transferred?
- What length of cable is to be installed?
- What is the ambient temperature where the cables are used?
- Are there any mechanical forces or chemical stressors affecting the cable?
- How are the cables installed? In pipes, open or closed cable ducts, cable conduits, on-wall or in-wall?
- How many cables are installed in the pipe, duct or conduit?
- How far apart are the cables in the conduit?
In some cases, we can provide reference values for advisory purposes. However, such data is always provided in a non-binding capacity and under consideration of the above points. It must also be pointed that full and adequate planning can only be performed by a recognised engineering consultancy. Written confirmations should not be provided!
Q. Can the steel wire armour of the ÖLFLEX® CLASSIC 100 SY also be used as EMC-compliant electromagnetic shielding or screening?
A: Although copper and steel are conductive metals, only copper (e.g. in the form of a braid) represents a suitable means of protecting a cable or wire from electromagnetic interference or shielding the environment from the interfering emissions originating from the cable itself. This not only depends on the electrical conductivity of the metal employed, but also on the braid density or the degree of coverage with which the cable is braided.
From all metals only pure silver offers marginally better conductive performance than copper. Although different qualities of iron/steel alloy exist, the conductivity of steel is generally six times lower than that of electrolyte copper. For this reason, a steel wire braid only ever protects a cable from external mechanical impact. To ensure optimized electromagnetic shielding, which also meets the requirements of the Electromagnetic Compatibility (EMC) directive, a sufficient level of copper braiding is required. As a minimum, a visual coverage level of 82-85% is required to achieve adequate screening protection. In the case of a steel wire braid used solely for mechanical protection, a visual coverage level of approx. 50% or less is standard.
With a little practice, it is therefore quite easy to visually distinguish copper and steel wire braids by their degree of coverage. In addition, copper braids often have a slight reddish tinge (despite their tin plating), are somewhat softer than steel and are in comparison to steel non-magnetic. However, even the densest, highest quality copper braid is rendered useless if it is not properly grounded! For safety reasons, steel wire braids should also be earthed when used in power networks. If the connected equipment develops a fault, this grounding prevents the transmission of dangerous voltages to the often exposed steel wire braid at the connecting points.
Q. How do you convert the AC system voltage value (AC) of an ÖLFLEX® cable into the corresponding DC system voltage value (DC)?
A: For virtually all of our ÖLFLEX® cables, the rated voltage is specified in the form of an AC value (Alternating Current). In a DC system (Direct Current), the rated voltage of the system must not be greater than 1.5 times of the rated voltage of the cable.
To calculate the DC Voltage value, the relevant AC Voltage value is simply multiplied by a factor of 1.5, as in the examples below:
AC Voltage Value Factor DC Voltage value
U0/U 300/500 V x 1.5 U0/U 450/750 V
U0/U 450/750 V x 1.5 U0/U 675/1125 V
U0/U 600/1000 V x 1.5 U0/U 900/1500 V
The electrical voltage is measured in Volt (V).
Q. In the technical data for ÖLFLEX® HEAT cables, what is the meaning of “adequate ventilation provided” under the temperature range specification?
A: Many operators and users are unaware that special factors have to be considered when installing cables in areas with raised ambient temperatures. This not only includes the self-heating resulting from the current load, but also the material-specific behaviour of the core and sheath insulation in high ambient temperatures. Non-electricians in particular are mostly not familiar with the fact that the ampacity of a cable is reduced as the temperature increases.
For example, an ÖLFLEX® CLASSIC 100 3 G 1.5 mm² can carry 18 A (100%) at an ambient temperature of +30°C. If the temperature rises to +60°C, the ampacity is reduced to 9 A (50%) – calculated on the basis of VDE 0298-4 / catalogue appendix table T12-1 or T12-2.
Due to a complex chemical conversion process (formation of orthosilicic acid), insulation materials like silicone, which are regularly used in ambient temperatures up to +180°C, can harden and embrittle prematurely as of +100°C in the absence of adequate ventilation. Exceeding the maximum permissible ampacity and associated self-heating also accelerates the aging process accordingly. To counteract this effect, adequate volumes of air or oxygen must be supplied to such cables and wires when operated in high ambient temperatures. If closed ducts, tubes or pipes are packed full of cables, this can often result in premature damage as a result of disintegrated insulation and cable sheaths or even corrosion of the copper conductor.