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Brake Resistors

Brake Resistors
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Product Range Resistors Braking Resistors FU www.jovyatlas.de www.jovyatlas.de www.jovyatlas.de To meet the nowadays demands of drive system technology, converter circuits with variable frequencies are used predominantly for controlling AC motors. When required by changes in speed or deceleration within the drive train, the engine‘s frequency is higher than the output frequency of the frequency converter. In this case the motor operates as a generator and delivers energy that is converted via braking resistor into heat in most cases. The operating mode of the braking resistor is determined by the operational condition of the engine. In general the braking resistor is switched on briefly only in order to store the surplus engine power. In the idle period the braking resistor emits the stored heat to the environment. This form of operation, known as intermittent operation, is characterized by the power-on time and by the cycle duration. The cycle duration is calculated as the sum of the braking time and idle period. The operation is composed of a series of similar games. If you configure the product of braking frequency and braking time and relate this value to a specified cycle time, the result is the cyclic duration factor, c.d.f.. During the idle period the resistor no longer cools down onto room temperature, i.e. after a certain number of cycle sequences the resistor elements adapt to a mean temperature. Therefore the parameters given above are used for the design of the braking resistor to prevent improper temperatures of the resistive elements. For dimensioning the braking resistors JOVYATLAS has developed thermal models for all types of resistors. Using these models any conceivable course of loading can be simulated and thus the temperature rise of the active resistance material can be calculated. The simulation results asure an optimal and reliable design of the braking resistor. JOVYATLAS uses the following components for manufacturing braking resistors FU: Wounded Braking Resistors: According with copper nickel wire wrapped on a ceramic tube (type PT1000) or of which are equipped with special porcelain brackets and on which CuNi44 copper nickel wire is wounded (type FU). The housing is made of galvanised sheet metal. Connection cable, terminal boxes or tapping points are optionally available. To achieve higher power ratings several tube resistors could be combined in modular design whereby versatile applications are possible. Types: PT1000 or FU Applications: Driving frequency converters with low/middle power range positioning: straight to the frequency converter Advantages: Technichal Data: - quick connection - small dimensions - requires little space - load range: 50W - 1kW - protection degree: IP00 – IP23 Leaflet Braking Resistors FU 08/2012

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Braking Resistors in Steel-Grid-Design Steel grid resistors are made of sheet metal panels with meander-outs. To achieve mechanical strength the longitudinal sides of the grids are reinforced, so that the elements can be assembled with insulated threaded bolts into blocks. This design ensures by its large surface area a particularly good heat dissipation whereby these resistors are suitable for large continuous operations. In addition, by the great mass of the resistor blocks very high pulse loads are possible. Applications: Driving frequency converters with middle/high power range...

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