Selecting and safety instructions by using our flexible and highly flexible braids, leadings, cables and ready assembled components

General advice

The measurements and technical information written in this catalogue have been determined with greatest care and are updated continuously in our documentation. We reserve as the right to make technical as well as changes of measurements, colours or formats after print. Our information especially the values for possible current-loads are not binding, they are only approximate values under optimized conditions. The relation between conductor cross-section and current-load fixed in national or international regulations are not cancelled through our information. Also it is necessary to pay attention to the following facts. Only the values in our written order confirmations are binding for us.

Demands to current transfer elements

All components for current transfer must be selected under the condition that by using the components in accordance with the regulations or requirements no unacceptable risk are created for life and health of persons as well as a damaging of objects. To guarantee these demands it is absolutely necessary to check and analyse possible risks, source of errors and rest risks even when planning or designing plants or products. All components for current transfer must be so calculated that they are sufficient dimensioned for all possible load (current as well as voltage) which can be occurred inside of the planed application. Particularly by existing limit conditions it is necessary to take the values of the current rates or voltages fixed in national or international regulations into consideration.

Values of influence

Following some short examinations of the fundamental facts, which have an influence of the construction of current transfer components. Please notice that it is important to consider and observe all facts together and not separately.

Selecting information

The fundamental facts for selecting the right current transfer components are the operating conditions and the outer influences. Operating conditions are the height of voltage and current, kinds of laying, the number of leadings or cables, the cooling possibilities, the safety devices etc. Outer influences are the ambient temperature, the existence of corrosive or other chemical substances, mechanical stress or special requirements concerning of the installation situation, the existence and influence of steam, moisture or radiation (e. g. sunlight). All these facts must be taken into account when constructing or designing solutions for current transfer applications.

Voltage

It is necessary to protect and insulate the flexible leadings and current transfer components in coordination with the existing voltage of the application. The operation voltage of leadings or cables are defined in Volt by the values U0/U. It is the voltage which determines the construction and the electrical test procedures of the leadings. Here is

U₀ = Value of the permissible voltage between an external conductor and earth

U = Value of the permissible voltage between two external conductors of multicore or a system of single core leadings

According to the regulations of the VDE 0298 part 3 the operating voltage of the leadings must be identical with the operating voltage of the whole system, when working with AC-voltage. This regulation is binding for the value U0 as well as for the value U. When working in a system with DC-voltage it is acc. to the VDE allowed to calculate with a maximum value of one and a half of the operating voltage of the leadings. But we recommend to exceed the value not more than 10 % continuously.

Current load

The cross-section of a conductor should be so selected that his allowed current load and the permissible maximum continuous current load of the application should be identical or greater. Additionally you have to take the permissible heat resistance of the used insulation material and the possible voltage drops into your account. Some fundamental facts which have influence of the dimensioning of electrical conductors are therefore:

• Kind of laying and number of the conductors
• Voltage drop and electrical losses
• Ambient temperature
• Insulation material and thermal stress
• Cooling possibilities
• Frequency of the current (when > 50 Hz)
• Consequences of electrical waves etc.

Such influences must be compensated by the consideration of necessary reducing factors. Additionally all thermical influences must be taken into account, so that it is not possible to hinder a thermical radiation and a danger of fire is excluded.

Mechanical stress

Also it is necessary to calculate the risks of a possible mechanical stress. Fundamental values can be created by a tensile-, pressure-, torsion- and bending stress or other facts created by the handling, transport or installation. Electrical elements which are particularly subjects of mechanical stress or flexible components which have to realize movements must be selected very carefully and well suited to the application. With pleasure our employees assist your efforts in finding optimized solutions.

Coordination of components to the different applications

When selecting flexible leadings, cables or components it is necessary to pay attention to the application, the installation, the ambient conditions and to all risks arising out of these facts. So a consideration of the following facts is important too:

• Avoidance of a possible mechanical or electrical influence between bordered power systems
• Thermical radiation as well as chemical or physical influences of the conductor, the insulation or other bordered materials
• Examination of possible influences or reactions between bordered materials and the conductor with his insulation
• Examination of the fixing and the fixing materials concerning possible damages e. g. caused by the dynamic strength in case of short circuit situations