JP4729324B2 - Surge current generator - Google Patents

Description

  The present invention relates to a surge current generator used for testing whether a lightning protection element or the like operates properly in a product incorporating the lightning protection element or the like.

  Conventionally, it is necessary to test whether or not a product performs a predetermined function, and it is necessary to test whether or not the lightning protection element operates properly even in a product in which the lightning protection element is incorporated. There is.

  The basic principle of such a test is to generate a pseudo lightning surge and input it to a product to test its operation and to withstand a surge current.

  For example, as a method for testing the surge current withstand capability, a method has been proposed in which a surge current withstand capability is measured from the amount of heat generated by the device by applying a pulse current of gradually increasing levels to the device (see Patent Document 1). .

  Although the surge current itself may enter the product alone, it often overlaps with the signal or the like. FIG. 3 is a circuit diagram of a surge current generator conventionally used for testing the operation check of a lightning protection element or the like in an intrusion mode that invades superimposed on such a signal or the like.

  The circuit in FIG. 3 is a surge current generating circuit, and the DC bias current is generated by a DC bias current generating circuit (not shown) and superimposed on the surge current and applied to the load.

  Such a surge current generator is of a capacitor discharge type, and rectifies that a rectifier 104 that rectifies an AC voltage, a capacitor 103 that is charged by the rectifier 104, and a predetermined charge is charged in the capacitor 103. When the unit 104 detects it, it comprises a discharge switch 105 that is controlled to close the discharge circuit, and resistors 106 and 107 that set a discharge time constant together with the capacitor 103, and a load (test body) is connected to the output. It has become.

  In order to allow a desired surge current to flow to the load during the test, the impedance (equivalent impedance) of the load 100 is confirmed, and the charging voltage of the capacitor 103 by the rectifier 104 is set based on this impedance, and the resistor 106 , 107 are set.

  When the setting of the charging voltage and resistance value is completed, charging of the capacitor 103 is started, and the voltage of the capacitor 103 is detected by the voltage detector 114 provided in the rectifying unit 104. When the detected voltage reaches the set voltage, the voltage detector 114 controls the discharge switch 105 to close the discharge circuit.

When the discharge circuit is closed, the electric charge of the capacitor 103 is discharged with a time constant determined by the equivalent impedance of the resistors 106 and 107 and the load 100, and a surge current flows through the load.
JP 2002-250752 A

  However, the surge current value is determined by examining the impedance of the load 100 in order to cause the surge current having the daily current value to flow to the load 100 according to the equivalent impedances of the resistors 106 and 107 and the load 100. It is necessary to set the resistance values 106 and 107 and the charging voltage, and there is a problem that a lot of time is required for preparation before starting the test.

  In addition, when a surge current is superimposed on a DC bias current, it is necessary to take measures to prevent the surge current from flowing into the DC bias current generation circuit side, or conversely, the DC bias current from flowing into the surge current generation circuit side. There was a problem that caused the circuit to become complicated.

  Therefore, the present invention provides a surge current generator in which a surge current having a target current value is superimposed on a DC bias current, and the surge current having the current value flows to the load regardless of the impedance of the load. The purpose is to provide.

In order to solve the above-mentioned problem, the invention according to claim 1 is directed to a DC power supply comprising at least a bias power supply terminal that provides a DC bias current supply source, a surge power supply terminal that provides a surge current supply source, and a bias power supply terminal. Connected to a DC bias current circuit that outputs a DC bias current of a predetermined value and a surge power supply terminal connected to the DC bias current for a predetermined time regardless of the impedance of the load. A surge current circuit that outputs so as to be able to flow to a load, and the surge current circuit includes a test start switch that is turned on at the start of a test, and a pulse having a time width that is preset according to the turning on of the test start switch A timer that outputs a signal, an application control transistor that outputs a surge current by turning on in response to a pulse signal from the timer, A voltage converter that generates a voltage value corresponding to the surge current value output through the control transistor, and a voltage value of the control gate in the application control transistor is changed according to the voltage value, and the output surge current value is characterized Rukoto a current control transistor for feedback control so that the preset current value.

As a result, even if a surge current is superimposed on the DC bias current and applied to the load, the current with the test current value superimposed on the load can be passed through the load with a simple configuration, regardless of the impedance of the load. Can be performed in a short time. In addition, a surge current having a predetermined time width can be applied to the load. In addition, a surge current having a predetermined current value can be applied to the load.

The invention according to claim 2, selected voltage converter, a resistor different groups comprising a plurality of resistors of resistance value, the first resistor in the resistor group so that the surge current can be output current value corresponding to the test object And a current value changeover switch.

  As a result, a surge current having a current value corresponding to the test purpose can be applied to the load.

The invention according to claim 3 is characterized in that a diode for preventing wraparound of the current output from each of the output terminals of the DC bias current circuit and the surge current circuit is provided.

  Thus, the DC bias current and the surge current can be superimposed only by connecting the output of the DC bias current circuit and the output of the surge current circuit.

According to a fourth aspect of the present invention, there is provided an inverter that outputs a pulse signal of one pulse when the test start switch is turned on to the timer, and a capacitor that suppresses the influence on the inverter due to chattering when the test start switch is turned on. And further comprising .

  As a result, the timer operates normally even if an inexpensive mechanical switch is used as the test start switch.

According to the present invention, a DC power supply including at least a bias power supply terminal that forms a DC bias current supply source, a surge power supply terminal that forms a surge current supply source, and a DC power supply having a predetermined value is connected to the bias power supply terminal. a DC bias current circuit for outputting a bias current, is connected to a surge power terminal, as the surge current of a predetermined value irrespective of the impedance of the load can be supplied to the load by superimposing only on a DC bias current a predetermined time output A surge current circuit, a test start switch that is turned on at the start of a test, a timer that outputs a pulse signal having a preset time width according to the turning on of the test start switch, and the timer An application control transistor that turns on in response to the pulse signal from the output and outputs a surge current, and outputs via the application control transistor A voltage converter that generates a voltage value according to the surge current value to be output, and a voltage value of the control gate in the application control transistor is changed according to the voltage value, so that the output surge current value becomes a preset current value Runode a current control transistor for feedback control such that, with a simple configuration, even when the DC bias current as applied to the load by superimposing a surge current, regardless of the impedance of the load, the test current value Thus, a current superimposed with the surge current can be passed through the load, and the test can be performed in a short time.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a circuit diagram of a surge current generator according to the present invention. Examples of the test target include DSU (Digital Service Unit) in an ISDN circuit that is required to withstand the invasion of a surge current of several hundred mA to several A, for example.

  The surge current generator 1 generates a surge current and a DC bias current, and superimposes these to output to a load 5. The surge current generator 2, the DC bias current generator 3, and these A DC power supply 4 for supplying power is provided.

  The direct current power source 4 receives alternating current, rectifies it into direct current, and outputs it. The output terminal is provided with a bias power source terminal T1, a surge power source terminal T2, and a circuit operation power source terminal T3. GND) terminal T4 is provided.

  For example, a medium voltage of + 60V is output to the bias power supply terminal T1, a high voltage of + 200V is output to the surge power supply terminal T2, and a low voltage of + 5V is output to the power terminal T3 for circuit operation. It has become.

  A constant current diode 11, a resistor 12, and a diode 13 are connected to the bias power supply terminal T 1 in this order and input to the terminal 14 a of the application switch 14. Therefore, when the application switch 14 is closed, a DC bias current having a current value determined by the constant current diode 11 is output to the load 5. That is, they operate as a DC bias current circuit 3.

  On the other hand, the surge current circuit 2 is configured as follows. That is, a resistor (voltage converter) 15, a transistor (application control transistor) 16, a resistor 17, and a diode 18 are connected in this order to the surge power supply terminal T 2 of the DC power supply 4 and connected to the terminal 14 a of the application switch 14. It is connected.

  Therefore, when the transistor 16 is turned on, the current from the surge power supply terminal T2 is applied to the load 5. This current acts as a surge current.

  The diode 13 prevents the surge current from the surge current circuit 2 from flowing into the DC bias current circuit 3, and the diode 18 prevents the DC bias current from the DC bias current circuit 3 from flowing into the surge current circuit 2. It is for doing so.

  Accordingly, it is possible to apply a current obtained by superimposing the DC bias current and the surge current to the load 5 only by connecting the outputs of the DC bias current circuit 3 and the surge current circuit 2.

  A timer 20, a resistor 24, and a capacitor 22 are connected to the circuit operation power supply terminal T3 of the DC power supply 4. The other terminal of the timer 20 is connected to the GND terminal T4, and power is supplied from the terminals T3 and T4. When the output of the inverter 23 becomes “H” level, a positive pulse having a predetermined time width (for example, 2 ms) is generated. A signal is output.

  The timer time may be arbitrarily set. Generally, in the case of lightning surge, the time width is almost fixed and may be fixed. However, the operation margin test of the specimen and different items (in this example, the operation test of lightning protection elements etc. In some cases, such as when a surge current resistance test is performed, it may be desired to test, and it is preferable that the timer time can be arbitrarily set so that it can also be used.

  On the other hand, the resistor 24 is connected to the terminal 21a of the test start switch 21 and to the inverter 23, and the terminal 21b of the test start switch 21 is connected to the GND terminal T4. The capacitor 22 is connected in parallel with the resistor 24.

  The inverter 23 is composed of a Schmitt circuit that outputs one pulse signal for one input, and the test start switch 21 is a switch that instructs the load 5 to apply a surge current. When the test start switch 21 is closed, The inverter 23 outputs one pulse of the pulse signal.

  However, since this test start switch 21 is composed of an inexpensive mechanical switch, chattering may occur when the test is started, and this inconveniences that a plurality of application commands are input to the inverter 23. . Therefore, the capacitor 22 is connected in parallel to the resistor 24 to suppress the influence of the chattering.

  That is, before the test start switch 21 is turned on, the potential from the circuit operation power supply terminal T3 is applied to the input terminal of the inverter 23, and the capacitor 22 is not charged. Since the potential from the circuit operation power supply terminal T3 is the “H” level potential, the output of the inverter 23 becomes the “L” level, and the timer 20 does not output a pulse signal.

  When the test start switch 21 is turned on in this state, the potential of the input terminal of the inverter 23 becomes “L” level, the timer 20 operates, and charging of the capacitor 22 is started. When the capacitor 22 is charged, chattering can be suppressed within the threshold range of the input terminal of the inverter 23 even if the test start switch 21 causes chattering.

  The output of the timer 20 is input to the base of the transistor 27 via the resistor 25, the emitter of the transistor 27 is connected to the GND terminal T4, and the collector is connected to the base of the transistor 16 via the resistor 28.

  Therefore, when a positive pulse signal is output from the timer 20, the base potential of the transistor 27 increases and turns ON. When no positive pulse signal is output from the timer 20, the GND potential is applied to the base of the transistor 27 through the resistor 26, so that the timer 20 is in the OFF state.

  When the transistor 27 is turned on, the base potential of the transistor 16 is lowered and turned on. At this time, if the application switch 14 is closed, the current from the surge power supply terminal T2 flows as a surge current to the load 5.

On the other hand, the surge power supply terminal T2 is connected to the emitter of the transistor (current value control transistor) 30 and is connected to the base via the resistor 15 and the resistor 29. The base of the transistor 30 is connected to the collector of the transistor 16 through the resistor 31 and is connected to the GND terminal T4 through the resistor 32.

  When the transistor 16 is turned on, a current flows through the resistor 15, so that the base voltage of the transistor 30 changes according to the value of the current flowing through the resistor 15. As the base voltage of the transistor 30 changes, the current flowing between the collector and emitter of the transistor 30 also changes, and the base voltage of the transistor 16 changes. When the base voltage of the transistor 16 changes, the current flowing between the collector and the emitter of the transistor 16, that is, the current flowing through the resistor 15 changes.

  By such feedback acting on the transistor 16 and the transistor 30, the surge current value flowing through the load 5 becomes a predetermined current value regardless of the impedance of the load 5. Accordingly, it is possible to prevent the inconvenience that the surge current having the target test current value does not flow to the load 5 or the surge current having an excessive current value flows to the load 5.

  Since the resistor 31 is set to a very high resistance value, the current flowing through the load 5 via the resistors 15, 29, 31, and 17 is very small and can be ignored.

  By the way, since it may be desired to test the current value of the surge current with a plurality of values, in such a case, the resistor 15 in FIG. 1 is replaced with a plurality of resistors 35a to 35c having different resistance values as shown in FIG. The resistors 35a to 35c having a resistance value corresponding to a desired current value may be selected. Each of the resistors 35a to 35c is selected by a current value changeover switch 36.

  Thereby, it becomes possible to flow a surge current according to the test purpose regardless of the impedance of the load 5, and convenience is improved.

It is a circuit diagram of the surge current generator applied to description of the best mode for carrying out the present invention. It is a fragmentary diagram of a circuit diagram of the surge current generator when the surge current value can be changed. It is a circuit diagram of the surge current generator applied to description of a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Surge current generator 2 Surge current circuit 3 DC bias current circuit 4 DC power supply 5 Load 11 Constant current diode 12, 17, 24, 25, 26, 28, 29, 31, 32, 35 (35a-35c) Resistance 13, 18 Diode 14 Application switch 15 Resistance (voltage converter)
16 transistor (application control transistor)
20 Timer 21 Test start switch 22 Capacitor 23 Inverter 27 Transistor 30 Transistor (current value control transistor)
36 selector switch

Claims (4)

A DC power supply comprising at least a bias power supply terminal that forms a supply source of a DC bias current and a surge power supply terminal that forms a supply source of a surge current;
A DC bias current circuit connected to the bias power supply terminal and outputting a DC bias current of a predetermined value;
A surge current circuit connected to the surge power supply terminal and outputting so that a surge current of a predetermined value is superimposed on the DC bias current for a predetermined time regardless of the impedance of the load and can flow to the load ;
The surge current circuit, a test start switch that is turned on at the start of the test,
A timer for outputting a pulse signal having a preset time width in response to turning on of the test start switch;
An application control transistor that turns on in response to a pulse signal from the timer and outputs a surge current;
A voltage converter that generates a voltage value corresponding to a surge current value output through the application control transistor;
Rukoto a current control transistor that said application control by changing the voltage value of the control gate of the transistor, a feedback control so that the surge current value to be output is preset current value according to the voltage value A surge current generator characterized by. Said voltage converter, the resistor group consisting of a plurality of resistors having different resistance values,
Surge current generator according to claim 1, characterized in that it comprises a current changeover switch for selecting one of the resistors in said resistor group so that the surge current can be output current value corresponding to the test object. The surge current generator according to claim 1 or 2, wherein a diode for preventing the wraparound of the current output from each of the output terminals of the DC bias current circuit and the surge current circuit is provided. An inverter that outputs a pulse signal of one pulse when the test start switch is input to the timer;
The surge current generator according to any one of claims 1 to 3 , further comprising a capacitor that suppresses an influence on the inverter due to chattering when the test start switch is turned on.

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