Remote feeding device

Details Remote feeding device Remote feeding device

1996-07-08

2001-01-09

Wong, Peter S. (Department: 2838)

Electricity: power supply or regulation systems

Output level responsive

Using a three or more terminal semiconductive device as the...

C323S285000

Reexamination Certificate

active

06172491

ABSTRACT:

BACKGROUND OF THE INVENTION
The invention relates to a remote feeder device. Such a remote feeder device is known from DE 31 09 087 C2.
The remote feeder device in accordance with DE 31 09 087 C2 has a current regulator and a voltage limiter, connected on the output side with the current regulator. The voltage limiter is used for limiting or reducing the d.c. voltage resulting at the start of the section, in particular in case of a section disruption. A comparator is provided, which measures the section resistance via a measuring resistor. The output voltage is limited to a reduced value in case of an increase of the section resistance past a preset maximum value. The nominal output current is only delivered at a load below a resistance of 1 Kiloohm. Above this resistance a reduction of the voltage to, for example 60 V, takes place for the protection of personnel.
An installation for regulating the constant current of the remote feeder current in a d.c. remote feeder system is known from DE 42 10 785 C1. The remote feeder current is detected by means of a current sensor in the form of a current measuring resistor, is evaluated in a control device and is processed into a control signal for a pulse width modulator of a switching regulator. The feeder energy for the regulating device is taken directly from the remote feeder loop. So that this current evaluation is not distorted, feeding of the control device is performed via a constant current source.
It is known from JP 63-178 764 (A) in “Patent Abstracts of Japan”, Sect. E, 1988, Vol. 12, No. 452, E-687, to detect the output voltage as well as the output current in an output circuit of a switching regulator for supplying a consumer, and to process a control signal for the switching regulator as a function of this.
SUMMARY OF THE INVENTION
It is the object of the instant invention to design a remote feeder device in such a way that it becomes possible to deliver as high as possible a remote feeder output, wherein protective rules in respect to permissible limit values, for example the maximally permissible contact voltage, are to be particularly observed.
The invention is based on the following realizations:
If the voltage of the feeder device is measured at its output terminals—as in the realization in accordance with JP 63-178 764—the remote feeder current is affected by the voltage evaluation circuit, i.e. a portion of the current flows through this evaluation circuit and is not available for remote feeding. Furthermore, the voltage evaluation at the output terminals is not usable for a high accuracy current evaluation. With the invention, the base point of the voltage limiter is adjusted, free of distortions in respect to the remote feeder current, in such a way that the voltage drop at the current sensor of the remote feeder current regulator is compensated for the voltage evaluation. Then the maximally possible contact voltage, in accordance with VDE 0800/DIN 57800 a remote feeder d.c. voltage of 120 V, is available at the output terminals of the remote feeder device. In contrast to the known solutions with a voltage limiter downstream of the current regulator, the maximally possible remote feeder output is therefore available, which increases the range of the remote feeding. The number of intermediate regenerators in message transmission systems, in particular glass fiber transmission systems, can be reduced because of the increased range.
The novel features which are considered as characteristic for the present invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.


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