R
24 Posts in this encyclopedia categoryRailway standard (DIN EN 50 155)
Standard that deals specifically with the operating conditions of electronic equipment on railway vehicles. (All information without guarantee)
RAL colour
The RAL colours with the four-digit number are the standard for colouring. The colour collection currently comprises over 200 colours. The basic collection for matt colours is the RAL 840HR register. The collection for glossy colours is the RAL 841-GL register. The basic collections are continuously adapted to the requirements of the industry. These collections cover a wide range of applications. The registers serve as colour templates for designs, but also include safety and signal colours and meet the colour specifications of DIN standards. (All information without guarantee)
Rated current
Current of a device or equipment for which the device or equipment is specified by a standard or by the manufacturer. As a rule, the value of the current resulting from the rated apparent power and rated voltage, forexample, the current specified by the manufacturer (preferably at an ambient temperature of 40 °C) that a connector can carry continuously. The rated current flows simultaneously through all its contacts, which are connected to the largest possible conductors. The upper temperature limit is not exceeded. (All data without guarantee)
Rated impulse voltage
Value of a withstand impulse voltage specified by the manufacturer for a piece of equipment or a part thereof. It indicates the specified withstand capacity of its associated insulation against transient overvoltages. (All data without guarantee)
Rated voltage
The rated voltage is the value of a voltage that is specified by the manufacturer for a component, device or piece of equipment and to which the operating and performance characteristics relate. The term "rated voltage" has been used in electrical power engineering since 1981 in order to better clarify differences to the nominal voltage in the standards. The rated voltage is greater than or equal to the nominal voltage and specifies the maximum value of the electrical voltage in normal operation. (All data without guarantee)
REACH
REACH Regulation (EC) No. 1907/2006 concerning the Registration, Evaluation, Authorisation and Restriction of Chemicals. With the REACH Regulation, the EU has created a uniform system for the registration, evaluation, authorisation and restriction of chemicals - known as REACH for short. The purpose of this regulation is to ensure a high level of protection for human health and the environment. (All information without guarantee)
Reactive current
The reactive current is a part of an alternating current that does not contribute to the useful conduction of a current like the active current, for example. (All data without guarantee)
Redundancy
Presence of equipment that is not required for the basic function. If a piece of equipment fails, the additional piece of equipment can take over its function. (All information without guarantee)
Reference potential
Potential from which the voltages of the circuits involved are observed and/or measured. (All data without guarantee)
Reinforcement
A special electromechanical or mechanical protection against external stress, to improve the reduction factor and to absorb tensile forces. In the case of fibre optic cables, plastic fibres are used and no metal reinforcement is used. It is also often defined as armouring. (All information without guarantee)
Release films, PETP films
Polyethylene terephthalate films are used as insulating films in the cable industry. They have very good dielectric and mechanical properties. They are used as separating films for PVC-insulated wires and cables. (All data without guarantee)
Residual currents
Residual currents occur in the event of faulty insulation and short circuits between live parts and earth. Such faults can lead to life-threatening contact voltages for people and animals. Residual current circuit breakers switch off system areas in which such faults occur within a few milliseconds. (All information without guarantee)
Resistance
Electrical - or ohmic - resistance. It is caused by the collision of moving charge carriers with atoms of the conductor. This inhibits the uniform movement of charge carriers - the flow of current. The resistance of a conductor decreases as the cross-section of the conductor material increases, as the electrons have more space in the conductor for the same current (= same number of charge carriers) and so there are fewer collisions with the metal lattice. The resistance also increases with a longer conductor length, as the probability of a collision over a longer distance increases. The resistance of metallic conductors increases with increasing temperature (PTC thermistors). Semiconductors are so-called hot conductors, which have a lower resistance with increasing temperature.resistance = voltage/current; "inhibition" for the current flow, expressed in ohms. The smaller the cross-section, the greater the resistance. The more ohms, the worse the current flow. (All data without guarantee)
Ribbon cable
Ribbon cable in which individual strands are welded together to form a ribbon (often multi-coloured) and usually in small cross-sections (0.08mm² or 0.14mm² or 0.25mm²). The individual wires can usually be separated. Application: In electronics for connecting printed circuit boards.
Ribbon cable
In flat ribbon cables, the individual conductors, which are insulated from each other with plastic, lie parallel to each other in one plane, so that the cable looks like a belt or flat ribbon.
RoHS
RoHS stands for Restriction of Hazardous Substances. Some of the substances used in electrical engineering are considered hazardous to the environment. Above certain quantities, they have a toxic effect or cannot be broken down by the environment, or only with difficulty. The aim of the RoHS directives is to ban problematic components from electronic waste. Directive 2011/65/EU (RoHS 2) replaced its predecessor Directive 2002/95/EC (RoHS 1) on 3 January 2013. Both directives are unofficially abbreviated to RoHS. (All information without guarantee)
Roller bracket
The force is transmitted during locking via a roller on the locking lever. (All information without guarantee)
Rope umbrella
Rope umbrellas are classically stranded onto the stranding system using a stranding machine. As they have no crossing elements, they are characterised by a high degree of flexibility. However, under bending stress, the canopy can open on the outside of the bending point, which leads to a deterioration of the canopy properties at this point. These negative shielding properties can be compensated for by attaching a second cable shield to the stranding in the opposite stranding direction and possibly with a different pitch angle. The shield is applied to wires and cables in the low-frequency range. (All information without guarantee)
Round conductor
The conductor cross-section of the round conductor is a circular area. It can be solid or stranded, compacted or non-compacted and made of copper or aluminium. It is used for all wires and cables. (All data without guarantee)
Rubber compounds
Rubber compounds usually consist of rubber (20-30 percent), fillers (approx. 60 percent), plasticisers (5-10 percent), retarders (0.5 percent), anti-ageing agents (approx. 0.8 percent) and dyes (0.5-2 percent). (All data without guarantee)