KR970004582B1 - Overcurrent relay - Google Patents

Abstract

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Description

Overcurrent relay

1 is a detailed circuit of the overcurrent relay according to the present invention.

2 is a flowchart showing the operation of the present invention.

* Description of the symbols for the main parts of the drawings *

1: trip coil 2: switch

5, 6, 7: Current transformers 8, 9, 10: Rectifier circuit

22: analog / digital converter 25: central processing unit

26: RAM 27: input / output device

31, 32: Dip switch 33: Variable resistor

34: Romans 42 ~ 45: Oagate

46, 47: address selector

The present invention is connected to a three-phase power supply, such as a factory equipped with a large number of mechanical equipment to determine when an abnormal condition, such as when the over-current flows for a predetermined time to determine the time to cut off the over-current at a set time It relates to an overcurrent relay.

In the past, when overcurrent flows to a load operated by a three-phase power source, a large number of overcurrent relays are cut off to cut off the supply power. However, since the overcurrent relay is cut off to some extent without considering the operating voltage of the load, it is immediately cut off. Followed by inconvenience in use.

To solve this problem, if an overcurrent flows to the load, it is determined whether the overcurrent is a temporary state or a continuous state, and if the temporary phenomenon is continuous, the power is continuously supplied to the load. Afterwards, many analog type overcurrent relays have been devised to completely cut off the power supply.However, the conventional overcurrent relay adopts an analog circuit and sets the cutoff time by the resistance and the time constant of the capacitor. It is weak to impulsive noise or the range of overcurrent is set by potentiometer, so the set value can be changed according to temperature, the response speed is slow, the volume of the device itself is large, the weight is not only high, There was a very weak problem.

In addition, according to the pre-registered stationary overcurrent relay (Utility Model Notification 92-3955 Utility Model Registration No. 70978), it is resistant to noise using a microprocessor, and can accurately count time using crystal oscillation. It can be set correctly, and the set value does not change according to the temperature, but it is not possible to remember the exact date and time of occurrence of an abnormal condition and also has the disadvantage of losing the data stored in the event of a power failure.

Accordingly, an object of the present invention is to provide a current relay that can store data even in the event of a power failure while remembering the time when an abnormal state such as overcurrent occurs, and also simplifies a method of setting various numerical values.

The present invention for achieving this object is a rectifying circuit for rectifying the alternating current flowing in the three-phase wire to a direct current in order to selectively cut off the power supplied to the load by sensing each current flowing in the three-phase wire And an overcurrent relay having an analog / digital converter for converting the rectified analog current signal into a digital signal, and a reference time generator comprising a crystal oscillator, a resistor, and an inverter to generate a reference time signal;

The address signal for the overcurrent cutoff set in the mode selection first dip switch, the detail selection second dipswitch and rotary encoder type variable resistors, and the address signal for the overcurrent value set by the dipswitch. Provides an address signal for the set overcurrent value to the RAM, ROM, and central processing unit through the data bus under the control of the address of the central processing unit, and turns off the power under the control of the central processing unit in the event of overheating or overcurrent of the switch. An input / output device for generating a; Compare the amount of change in the signal input from the input / output device and the current input from the analog / digital converter, and compare the amount of change in the input current before the time set by the variable resistor, but input before the time elapsed by the variable resistor. If the amount of change in the current is higher than the set value, the output of the input / output device is set to a low state. If the amount of change in the input current is continuously higher than the set value after the elapsed time, the output of the input / output device is set to a high state. A central processing unit for controlling the input / output device so as to be controlled; RAM and ROM controlled by the central processing unit to record and read various data signals; An ore gate and an address selector for generating a signal operating under the control of said central processing unit to control said RAM, input / output device, ROM, and analog / digital converter; A transistor and a light emitting diode operated when the signal generated by the input / output device is in a high state; A photocoupler comprising a light emitting diode and a phototransistor which generate light rays when the light emitting diode is turned on; It is composed of transistors that are turned on during the operation of the photocoupler to turn off the coil and the switch.

Hereinafter, the stationary overcurrent relay according to the present invention will be described in more detail with reference to the accompanying drawings.

1 is a detailed circuit diagram of the over-current relay according to the present invention, the 220V three-phase power supplied from the outside is supplied to the load not shown through the wires (S, T, N) bar, the lead coil connected to the load An earth leakage breaker operated by the switch (1) and (2) is connected.

Then, one end of the trip coil 1 is connected to the switch 4, which is turned on by the operation of the coil 3 as described in detail later, to cut off the power supplied to the load when an overcurrent occurs.

To this end, current transformers 5, 6, and 7 are installed in each of the three-phase wires to sense a change in the amount of current, and each current transformer 5, 6, and 7 is connected to each of the alternating currents induced by these current transformers by direct current. To rectify, rectifier circuits 8, 9, and 10 composed of a plurality of rectifier diodes are connected, and ceramic varistors 11, 12, and 13 are installed between respective lines to absorb sudden current.

The signals rectified by DC in each of the rectifier circuits 8, 9, and 10 are smoothed by the capacitors 14 to 19, respectively, and then the level is adjusted by the variable resistor 20 to analog / digital through the diode 21. It is input to the voltage input terminal (+ VI) of the converter 22.

At this time, the analog / digital converter 22 inputs an analog signal applied to its input terminal (+ VI) according to the clock pulse obtained by the resistor 23 and the condenser 24 through its digital output terminals DB0-DB7. The signal is converted into output and provided to the central processing unit (CPU) 25, the RAM 26, and the input / output device 27 through the data buses D0-D7.

Here, the RAM 26 adds a backup function by the battery 26a so that data can be stored even during a power failure.

On the other hand, the current obtained from the separate current transformer 28 is converted to a DC voltage by the rectifier circuit 29 and maintained at a predetermined level by the constant voltage IC 30, and then the power is supplied to each circuit shown in FIG. Supply (+ Vcc).

The first dip switch 31 is for selecting modes such as ground fault, under voltage, short circuit, overcurrent, and internal temperature rise, and the second dip switch 32 is in the above mode. It is for selecting and setting the details and the number of digits. For the specification selected by the first and second dip switches 31 and 32, the variable resistor 33 of the rotary encoder method is set to an arbitrary value. Can be set variable.

Accordingly, the time and current values set by the dip switches 31 and 32 and the variable resistor 33 are input to the input / output device 27, and the input / output device 27 is connected to the input set time and current values. As well as the corresponding data, the data of the temperature value of the contact detected by the temperature sensor 55 is provided to the data terminals D0 to D7 of the CPU 25 and the wrap 26.

At this time, the ROM 34 supplies the data signal stored therein to the central processing unit 25 under the control of the central processing unit 25.

On the other hand, the central processing unit 25 is connected to the clock signal generator of the crystal oscillator 35, the resistors 36 and 37 and the inverters 38 to 42 to generate an accurate reference time.

Also, the central processing unit 25 has an oragate 43 to 46 for generating a signal for the central processing unit 25 to control the above-described RAM 26, input / output device 27, and ROM 34. And address selectors 47 and 48 are connected.

In addition, the input / output device 27 displays numbers and molecules on the alphanumeric display unit 57 through the LCD driver 56 under the control of the central processing unit 25 and simultaneously emits light emitting diodes LED1 to LED4. While operating, it generates a signal for driving the coil 3.

That is, when a high state signal is generated at the terminal PC4 of the input / output device 27, the transistor 50 is turned on through the resistor 49, and accordingly, the light emitting diode LED1 is operated to operate the photodiode 51. ) Works too.

At this time, the phototransistor 52 is turned on to turn on the transistor 54 via the resistor 53 to operate the coil 3 to turn on the trip coil contact 4.

Therefore, since the trip coil 1 constitutes a closed circuit, the switch 2 which is turned on is turned off to cut off the power supplied to the load, which will be described in more detail as follows.

First, before operating the circuit of FIG. 1, the user selects a mode such as overcurrent, ground fault, low voltage, and temperature rise inside the short circuit of the line using the first dip switch 31, and then uses the second dip switch 32 again. After selecting the digits of each current value and time as well as the details of the long time, short time and instantaneous time in the overcurrent, the setting value according to each option is added according to the state of adjusting the resistance value of the variable resistor 33. A random value is selected by the rotary encoder method which subtracts.

The interruption time and the overcurrent value set in this way are respectively applied to the address terminals of the input / output device 27, and accordingly, the central processing unit 25 outputs the address signal to the input / output device 27 to control the set digital data. It transmits to the RAM 26 and the central processing unit 25 via the bus (D0 ~ D7).

In the central processing unit 25 receiving data, the LCD driver 56 is displayed as numbers and letters on the alphanumeric display unit 57 while driving the LCD driver 56 through the address terminals PB0 to PB7 of the input / output device 27. Let the user know.

On the other hand, the signal rectified by the current transformers 5, 6, and 7 is continuously input to the analog / digital converter 22 via the diode 21.

Therefore, when a signal according to the fluctuation state of the input is input to the analog / digital converter 22, the analog / digital converter 22 converts the input analog signal into a digital signal and performs central processing through the data buses D0 to D7. To the device 25.

At this time, the oscillation signals generated by the crystal oscillator 35 and the resistors 36 and 37 and the inverters 38 and 39 constituting the reference time generator connected to the central processing unit 25 may drive the inverters 40, 41, and 42. Since the central processing unit 25 is provided as a clock signal via the central processing unit 25, the central processing unit 25 first applies an input / output request signal IORQ to one of the input terminals of the oragate 43 and the oragate 46. The write signal WR is generated and input to the oragate 45 and the oragate 46.

OA gate 46 operates analog / digital converter 22 in write mode.

In addition, the write signal generated at the OR gate 44 is input to the write terminal WR of the input / output device 27. In addition, a signal generated at the oragate 43 is applied to the write enable terminal WE of the wrap 26 to operate the RAM 26 in the write mode.

In this write mode, the digital signals set by the dip switches 31 and 32 and the variable resistor 33 are input through the address terminals of the input / output device 27. Thereafter, the CPU 25 generates a read signal RD and applies the read signal RD to the oragate 43 and the oragate 44.

The read signal generated by the OA gate 43 is simultaneously input to the analog / digital converter 22 and the read terminal RD of the input / output device 27, where the analog / digital converter 22 is currently input. The signal is converted into a digital method using the pulses determined by the resistor 23 and the condenser 24 and transmitted to the central processing unit 25 through the data buses D0 to D7, and the input / output device 27 Transmits the input signal to the RAM 26 and the CPU 25 through the data buses D0 to D7.

Then, the CPU 25 compares the signal input from the analog / digital converter 22 with the data signal input from the input / output device 27.

That is, address signals are applied to the RAM 26, the input / output device 27, the ROM 33, and the address selectors 47 and 48 through the address buses A0 to A15, respectively, to enable them.

The signal input from the RAM 26 is compared in the comparator in the central processing unit 25, if the signal input from the analog / digital converter 22 is smaller than the signal transmitted from the input / output device 27. In this case, the central processing unit 25 outputs an address signal to the input / output device 27 to bring the output terminals PC4 to PC7 all low.

At this time, the light emitting diodes LED2 to LED5 operate.

However, when the signal input from the analog / digital converter 22 is larger than the signal input from the input / output device 27, the central processing unit 25 first of all has a dip switch 32, 32 and a variable resistor. The time set by (33) is counted. For example, when the setting time is 16 seconds, the central processing unit 25 performs the down count.

In the middle of performing this down count (16 → 15… 0 seconds), if the signal input before 16 seconds has elapsed lower than the actual signal by the user, the central processing unit 25 receives the address signal as described above. The terminal outputs the terminal PC5 to PC7 in a low state, and keeps the terminal PC4 in a low state.

However, when all of the down counts are completed, that is, when "0" seconds is reached, the terminal PC4 of the input / output device 27 becomes high to turn on the transistor 50 via the bias resistor 49.

When the transistor 50 is turned on, the light emitting diode LED1 operates, and accordingly, the light emitting diode 51 constituting the photo coupler operates to generate a light beam to turn on the phototransistor 52.

When the phototransistor 52 is turned on, the current flows through the coil 3 because the transistor 54 is turned on by the voltage signal via the resistor 53.

At this time, since the contact point 4 is turned on, the trip coil 1 is turned off to switch off the switch 2 to cut off the power supplied to the load, thereby protecting the load from overcurrent.

And the operation of the present invention will be described according to the flowchart of FIG.

The user selects a mode such as low voltage, overcurrent, and internal temperature rise using the first dip switch 31 (step 100), and again, a time limit, a time limit, and a time limit of the over current using the first dip switch 32. Instantaneous, of course, to select the value of the voltage and current and the details according to time (step 101), and then input the data of the numerical value according to each detail through the variable resistor 33 (step 102), input / output The central processing unit 25 receiving data through the device 27 initializes the internal data (step 103), and the analog / digital converter 22, the RAM 26, and the ROM 34 are newly inputted by the newly input data. ) To start the operation (step 104), and operate the LCD driver 56 via the input / output device 27 so that the numerical value of the details and data that the user selects and sets by the alphanumeric display unit 57 is set. To view (step 105).

Then, the detection results of the current transformers 5, 6, and 7 are inputted through the analog / digital converter 22 to check whether the ground fault is present (step 106), and if it is corrected, the resistance of the RAM 26 is checked by checking the occurrence time of the ground fault. While (step 107), the light emitting diode is turned on (step 108), and the occurrence time and current value of the ground fault are displayed via the alphanumeric display unit 57 (step 109).

In step 106, if it is not a ground fault, it is checked whether it is low voltage (step 110), and if it is corrected, the time is checked from the time of occurrence and stored in the RAM 26 (step 111), while the corresponding light emitting diode is turned on (step 112). The generation time of the low voltage and the low voltage value are displayed on the display unit 57 (step 113).

In step 110, it is checked by checking the wires of each phase whether it is a low voltage or not (step 114), and if it is corrected, turning on the corresponding light emitting diode (step 115), the number of phases of the shorted wires is changed, and the character display unit 57 is changed. (Step 116).

If it is not a short circuit in step 114, it is checked whether it is an overcurrent (step 117), and in which phases (S, T, N) the long-time, short-time and instantaneous currents are generated (step 118), and if it is correct, the current is increased again. While calculating the time (step 119), while calculating the decreasing delay time (step 120), the light emitting diode is turned on (step 121), and the above detection result is displayed on the alphanumeric display unit 57 (step 122).

If it is not the overcurrent in step 117, it is checked whether the temperature of the contact point of the switch 2 input through the temperature sensor (TH) 55 is in an overheat state (step 123). After operation (step 124), the light emitting diode is turned on (step 125), and the number is displayed to the outside through the character display unit 57 (step 126).

While detecting the abnormal state, the input state of another key is checked (step 127), or the selected specification is processed first (step 128), or real time is calculated so that accurate time calculation is performed (step 129).

Therefore, according to the overcurrent relay of the present invention, the numerical data is input by using the rotary encoder variable resistor 33 while selecting the user's options with the first and second dip switches 31 and 32. The user's setting is easy, and the input / output device 27 receiving the data is operated to operate the alphanumeric display unit 57 through the LCD drive 56 so that the user can recognize the operation state quickly and accurately. Of course, the overheating state at the contact point of the switch 2 can be recognized by the temperature sensor 55 to check whether the inside is in an abnormal operation state such as a defective contact, and at the same time, the backup unit installed in the RAM 26 The battery 26a is characterized by preventing the loss stored even in the event of a power failure.

Claims (1)

In the overcurrent relay, the mode selection signal through the first dip switch 31, the details of each mode through the second dip switch 32, the numerical information and the temperature sensor 55 input through the variable resistor 33 Input / output device 27 to receive the temperature sensing results from the input to the central processing unit, and displayed on the alphanumeric display unit 57 by numbers and letters by the signal output through the input / output device 27 An overcurrent relay, characterized in that consisting of LCD driver 56.