Electricity: electrical systems and devices – Safety and protection of systems and devices – With specific current responsive fault sensor
Patent
1999-06-24
2000-11-14
Ballato, Josie
Electricity: electrical systems and devices
Safety and protection of systems and devices
With specific current responsive fault sensor
361 931, 700292, H02H 300
Patent
active
061478474
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a circuit arrangement for detecting the current of current conductors, having one secondary phase winding per current conductor in order to activate electronically controllable tripping devices, having a line voltage supply device, with the operating voltage generated by the line voltage supply unit being compared to a reference voltage and the tripping device being activated by a limit voltage that forms when an overcurrent is reached; and a measuring potential input being provided for each secondary phase winding, with the measuring voltages being tapped by load resistors that are connected to the negative outputs of rectifiers, and each secondary phase winding being connected to a common voltage-stabilized Zener diode via a downstream diode, and the operating voltage being supplied by a charging capacitor.
BACKGROUND INFORMATION
European Patent No. 0 469 207 describes a circuit arrangement that is equipped with load resistors which are assigned to current conductors and provide a separate measuring potential input for each secondary phase winding. Diodes that establish a connection to the common voltage-stabilized Zener diode and supply the operating voltage via a charging capacitor are connected downstream from the secondary windings. Generation of the operating voltage is decoupled from generation of the measuring signals by diodes.
As described in World Patent No. 90/12342, decoupling is also achieved by bypass circuits, in which the power supply system is decoupled from the current peak values to be measured.
As described in European Patent Application No. 0 687 050 the operating voltage is generated and the current detected by analog-controlled switching elements which are also supplied individually for each current conductor. In this regard, pure a.c. measurements using evaluation circuits are also described in which a separate load resistor is provided for each current conductor. Because the load resistors also have resistance values that are subject to specific tolerances, the measurement results obtained during current detection are imprecise.
Furthermore, a power supply unit for overcurrent tripping devices which control the necessary operating voltage in conjunction with a microprocessor is described in German Patent Application No. 32 23 687. However, the measuring circuit used in this case to detect the current is not decoupled from the circuit for generating the operating voltage, which means that mutual disturbances occur, resulting in imprecise measurement results.
SUMMARY
An object of the present invention is to provide a circuit arrangement for detecting the current of current conductors which reduces the amount of costly high-precision components, in particular load resistors, and also considerably improves the measurement procedure used for current detection and evaluation.
According to the present invention, this object is achieved by the following features including:
the circuit arrangement has a microprocessor device with a number of measuring potential inputs equal to the number of secondary phase windings;
each secondary phase winding is connected to a multiway rectifier device, whose positive outputs are connected to an input of a regulating transistor via a corresponding downstream diode;
the negative outputs of the multiway rectifier devices are all connected to one output of the regulating transistor, which is connected in an electrically conductive manner to a supply voltage output of the microprocessor device and a terminal of one load resistor;
a further terminal of the one load resistor simultaneously forms the first inputs of a number of measuring transistors equal to the number of secondary phase windings and a common line potential input of the microprocessor device;
the second inputs of the measuring transistors are each connected to the corresponding positive outputs of the corresponding multiway rectifier devices;
the operating voltage is supplied to a supply voltage input of the microprocessor device b
REFERENCES:
patent: 4713608 (1987-12-01), Catiller et al.
patent: 5179495 (1993-01-01), Zuzuly
patent: 5283708 (1994-02-01), Waltz
Hochgraef Holger
Wegener Mario
Ballato Josie
Huynh Kim
Siemens Aktiengesellschaft
LandOfFree
Circuit arrangement for detecting the current of a current condu does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Circuit arrangement for detecting the current of a current condu, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Circuit arrangement for detecting the current of a current condu will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2071203