KR930006948Y1 - Power circuit for breaker - Google Patents

Abstract

No content.

Description

Control circuit of circuit breaker

1 is a control circuit diagram of a conventional circuit breaker.

2 is a control circuit diagram of a circuit breaker according to the present invention.

3 is a trip control characteristic diagram according to FIG.

4 is a flowchart of operation according to FIG. 2;

* Explanation of symbols for main parts of the drawings

1: rectifier 2: burden and voltage source

3: filter and sample / hold circuit 4: analog / digital converter

5: microprocessor 6: trip device

11: static current setting means 12: switching unit

Z1-Z4: Zener diode V _R1 : Variable resistor

The present invention relates to a control circuit of a circuit breaker, and more particularly, to a control circuit of a circuit breaker that can be ideally operated in the lower feeder by varying the breaking capacity according to the rated setting current value.

Generally, general circuit breakers, magnetic contactors, and relays are used as circuit breakers for protecting a system from overcurrent, and this is inevitably applied in industrial fields. The ultimate goal of these products is to protect the assets against damage to assets such as human body protection, fire prevention and equipment damage. Technology should be developed and applied.

Here, the protection method refers to protection coordination, selective protection, and cascading, and this protection method has four characteristics such as long time, short time, instantaneous time, and short circuit. use.

In this case, the short circuit characteristic is an important characteristic and can be referred to as the life of the breaker current together with the mechanism.

As shown in FIG. 1, the control circuit of the conventional circuit breaker includes a current converter CT for detecting a three-phase power source (3? 3W), a rectifier 1 for full-wave rectifying the power source detected by the current transformer CT. And a load and voltage source 2 for level-adjusting the rectified DC power supply of the rectifying unit 1 to voltage output, and a filter and a sample / hold circuit for filtering and sample / holding the load and the output voltage of the voltage source 2. And an analog / digital converter 4 for converting the output signal of the filter and the sample / hold circuit 3 into digital data, and the analog / digital converter 4 and the filter and sample / hold circuit 3. The microprocessor (5) generates a synchronous clock and generates trip control signals such as long time, short time, instantaneous time, short circuit, etc. by receiving the output data of the analog / digital converter (4). And trip control scene of the microprocessor 5 And a zener diode ZD1 for supplying a short circuit operation signal of the trip device 6 to a tripping device 6 which performs a circuit breaking operation according to an overcurrent detection, and a predetermined zener voltage abnormal value among the output voltages of the rectifier 1. And a resistor R1.

In the control circuit of the conventional circuit breaker configured as described above, the current transformer CT detects a three-phase power source and performs full-wave rectification by the rectifier 1.

The power source rectified by the rectifier 1 is leveled through a load and a voltage source 2, and then leveled and filtered and sampled and held in the filter and the sample / hold circuit 3 by the voltage output. When the sample / holded signal is converted into digital data by the analog / digital converter 4 and input to the microprocessor 5, the microprocessor 5 performs arithmetic processing to perform long-term, short-time, instantaneous, A trip control signal such as a short circuit is generated. At this time, since the zener diode ZD is applied to the rectifier 1 with the rectified voltage at the cathode side, it operates as a peak detector and operates the trip device 6 when the peak value is equal to or higher than the zener voltage.

The microprocessor 5 can be used to select and vary characteristic curves such as long time, short time, instantaneous, and short circuits, but the short circuit characteristic is a simple function and the short circuit capacity cannot be moved according to the current variation. When such a technique is used for the mechanism mechanism, only the same effect as that of using the magnetic trip unit is obtained.

That is, there is no blocking effect due to the current adjustment.

This method is widely used in Japan, Europe, etc., and is also applied to domestic analog control circuits.

However, in the control of the circuit breaker, if the breaking capacity according to the static current value is changed according to the user's request even in the same current frame, the breaking speed effect can be seen, so that the high feeder protection is sufficiently protected. Although good results can be obtained to prevent breakage of the breaker itself, the breaking capacity of the current breaking airflow is the same for each rated current as shown in FIG.

The present invention devised a control circuit of a circuit breaker that allows the rated current to be set in consideration of such a problem and changes the existing uniform duty of operation by varying the breaking capacity for each rated current. This will be described in detail with reference to the accompanying drawings.

2 is a control circuit diagram of a circuit breaker according to the present invention, and as shown therein, a rectifier 1 for full-wave rectifying the three-phase power detected through the current converter CT and the output of the rectifier 1 are burdened. A load and voltage source 2 for converting the voltage and the output voltage of the voltage source 2 through a circuit, a filter and a sample / hold circuit 3 to sample / hold the load and an output voltage of the voltage source 2, and a filter and a sample / hold circuit Analog / digital converter (4) for converting the output signal of (3) into digital data, and output data of the analog / digital converter (4) are input and subjected to arithmetic processing in accordance with a program for a long time, a short time, an instantaneous time, In a control circuit of a circuit breaker comprising a microprocessor (5) for generating a trip control signal such as a short circuit and a trip device (6) for circuit breaking control according to the trip control signal of the microprocessor (5), the variable resistor Via (V _R1 ) The rated current setting means 11 for setting the rated current and the output of the rectifying unit 1 are commonly applied to the cathode side of the zener diodes Z1-Z4, and the set rated current of the microprocessor 5 The switching unit 12 includes a switching unit 12 for selectively switching the outputs of the anodes of the zener diodes Z1 to Z4 and outputting the cutoff control signal of the trip device 6.

Referring to the operation and effects of the present invention configured as described above are as follows.

The 3-phase power supply (3 ø3W) is detected using a current converter (CT0), full-wave rectified by the rectifier (1), and the output of the rectifier (1) is converted to a voltage source through the load and voltage source (2) and then filter And a sample / hold in the sample / hold circuit 3 to convert it into digital data in the analog / digital converter 4. The digital data is input by the microprocessor 5 according to the characteristic curve algorithm of the current converter CT. The trip device 6 generates a trip control signal for long-time, short-time, instantaneous and short-circuit control according to the calculated result, and drives the trip device 6. The long-time, short-time, etc. in the characteristic curve are irrelevant. Instantaneously, the characteristics of the short circuit side change according to the rated current.

FIG. 3 is a trip control characteristic diagram according to the present invention, and FIG. 4 is an operation flow diagram according to FIG. 2, in which a user inputs an analog / digital converter 4 through a variable resistor V _R , which is a rated current setting means 11. When the rated current is set, it is read by the microprocessor 5, which causes the microprocessor 5 to address control the switching section 12. The switching unit 12 selects the zener diodes Z1-Z4 according to the address control of the microprocessor 5, and the selected zener diodes Z1-Z4 have the maximum current rectified by the rectifier 1. When the voltage is higher than the voltage, the trip device 6 trips.

That is, the instantaneous and short circuit characteristics are selected as in FIG. 3 in accordance with the set rated current value.

Therefore, the zener diodes Z1-Z4 are selected in accordance with the conversion of the rated current through the variable resistor V _R , and the instantaneous and short-circuit characteristic curves automatically determine the lower curve as shown in FIG. Can be prevented.

As described above, in the conventional static breaker control, the uniform short circuit current interruption is the same regardless of the rated current type, and thus, instantaneous and short circuit characteristics may overlap in a frame having a wide rated current range. In this case, since the existing breaker can not be controlled variably, the interruption operation is performed even when the interruption operation is not necessary depending on the load, and thus unnecessary interruption of operation is involved during operation. In this design, the operation of the redundant operation is determined according to the trip time in this case, so that the short-circuit rated capacity is changed for each rated current so that the instantaneous and short-circuit operation can be overlapped by converting the rated current so as to prevent overlapping. It has the effect of sufficiently protecting the speed effect and the lower feeder protection as well as preventing the breaker itself from being damaged.

Claims (1)

Detects the current of the three-phase power supply and rectifies it in the rectifying unit 1, converts the output of the rectifying unit 1 into voltage, and receives the microprocessor 5 as digital data and interprets it according to an algorithm. In a circuit breaker control circuit configured to control the trip device 6 by means of instantaneous and short-circuit trip control signals, comprising: a zener diode (Z1-Z4) for detecting the maximum value of the rectifier 1 with different control voltages, and The Zener is controlled by the address control of the microprocessor 5 according to the rated current setting means 11 and the rated current setting means 11 for setting a current and inputting the digital signal to the microprocessor 5. And a switching unit (12) for selecting the diodes (Z1-Z4) and controlling the trip device (6) with a variable capacitance according to the rated current.