JPH073108U - Safety device for magnetic desorption device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a safety device for preventing a high voltage from being output from a thyristor when a magnetic field generating coil is disconnected in a magnetizing device or a demagnetizing device. [Structure] A voltage dividing circuit 1 configured to divide a high voltage by including a resistor 11 connected in parallel to a thyristor 6a of a magnetizing device and resistors 11 to 13 connected in parallel to a magnetic field generating coil 1.
0, the low-pass filter 14 that receives the divided voltage of this voltage-dividing circuit as an input, the charge interruption control circuit 15 and the breaker 3 that interrupt the charging operation of the charging circuit 5 when the output voltage of the low-pass filter reaches a predetermined level. Is equipped with. The voltage dividing circuit 10 is configured to reach a predetermined level with the divided voltage at the rising point of the high voltage in a state where the parallel connection is released due to the non-connection of the magnetic field generating coil 1.
The low-pass filter 14 has a high-cut characteristic capable of attenuating the output voltage of the thyristor 6a in the connected state of the magnetic field generation coil 1 so as not to reach a predetermined level.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention is configured by connecting a thyristor controlled to be fired so as to generate a magnetic field for magnetizing or demagnetizing after completion of charging, between a charging circuit for charging a charging capacitor to a high voltage and a magnetic field generating coil. The present invention relates to a safety device for a magnetic desorption device.

[0002]

[Prior art]

 In this type of magnetizing device or demagnetizing device, a high voltage is applied to a cored or air-core magnetic field generating coil and a large current is supplied to generate a magnetic field for magnetizing or demagnetizing. There is. This magnetic field generating coil has low resistance, but if the wire is disconnected or disconnected, the output end of the thyristor goes into a high-impedance state, and if a worker touches the coil or coil connecting terminal, the thyristor ignition control will be performed. Alternatively, there was a problem that the thyristor was ignited by its dv / dt characteristic and a high voltage was applied, resulting in electric shock even if it did not result in fatal injury. Also, when a plurality of magnetic field generating coils are selected by a switch, regardless of whether there is a break or the like, if switching is inadvertently performed while the device is operating, there is a problem such as sparking through the switch. there were.

[0003]

[Problems to be solved by the device]

 However, conventionally, no particular consideration has been given to the problem caused by such a high voltage.

Therefore, the object of the present invention is to provide a safety device for a magnetic desorption device of the kind described at the beginning which can prevent a high voltage from being output from the thyristor when the magnetic field generating coil is disconnected. And

[0005]

[Means for Solving the Problems]

 In order to achieve this object, the present invention generates a magnetic field for magnetizing or demagnetizing between the charging circuit and the magnetic field generating coil, which receives a boosted commercial voltage as an input and charges the charging capacitor to a high voltage. In a magnetic desorption device in which a thyristor controlled to be fired is connected and the charging time is set longer than the firing time of the thyristor, in the high impedance state due to the disconnection of the magnetic field generating coil. This is a safety device that prevents high voltage output from the thyristor.It is composed of a resistor connected in parallel with the thyristor and a resistor connected in parallel with the magnetic field generation coil, and a voltage divider circuit that divides the high voltage. A low-pass filter that receives the divided voltage of the circuit as input, and a charge interruption procedure that interrupts the charging operation of the charging circuit when the output voltage of this low-pass filter reaches a specified level. The voltage divider circuit is configured to reach a predetermined level with the divided voltage at the time of rising of the high voltage when the parallel connection of the magnetic field generation coils is released due to the disconnection of the magnetic field generation coils. The low-pass filter is characterized by having a high-cut characteristic capable of attenuating the output voltage when the thyristor is ignited in the connected state of the magnetic field generating coil so as not to reach a predetermined level.

[0006]

[Action]

 In normal operation, the charging voltage is applied to the magnetic field generating coil by controlling the firing of the thyristor for magnetization or demagnetization when the charging circuit charges the specified high voltage. A current corresponding to the resistance value flows, and a magnetic field for magnetizing or demagnetizing is generated. At this time, the voltage instantaneously applied to the magnetic field generating coil by thyristor ignition is attenuated by the low-pass filter, and the output voltage cannot reach the predetermined level.

When the magnetic field generating coil is disconnected, the voltage dividing circuit is connected in parallel by the low resistance magnetic field generating coil, that is, a substantial short circuit is released. It performs a pressure function, and the divided voltage at the start of charging is output from the low-pass filter with almost no attenuation due to the gentle charging characteristic compared to ignition, and the charging interruption means is activated.

[0008]

【Example】

 FIG. 1 shows a circuit configuration of a magnetizing device having a safety device according to an embodiment of the present invention. In the figure, 1 is a magnetizing magnetic field generating coil with an air core or a yoke, to which a flywheel diode 2 is connected in parallel. Reference numeral 3 is a breaker that cuts off the commercial power supply voltage supplied to the step-up transformer 4. Reference numeral 5 is a charging circuit composed of a thyristor 5a and a charging ignition control circuit 5b, which charges the charging capacitor 5c to, for example, 2 kV by the ignition control of the secondary side voltage of the step-up transformer 4 by the thyristor 5a. Reference numeral 6 denotes a voltage application circuit, which is composed of a unidirectional thyristor 6a and a voltage application ignition control circuit 6b. The ignition voltage of the thyristor 6a immediately after completion of charging causes the charging voltage of the charging capacitor 5c to pass through the magnetic field generating coil 1. To discharge. Reference numeral 7 is a discharge circuit of a charging capacitor 5c composed of an electromagnetic switch 7a and a discharge resistor 7b. By closing the contact of the electromagnetic switch 7a for a predetermined time after the operation of the magnetizing device, charging is performed through the discharge resistor 7b. The residual voltage of the capacitor 5c is discharged.

The charging circuit 5 controls ignition so that the magnetic material is sequentially charged so as to be slowly charged within, for example, about 5 seconds within a magnetizing work time interval, and the cost of related parts such as the step-up transformer 4 is reduced. I try not to make it unnecessarily expensive. On the other hand, the voltage application circuit 6 instantly discharges the charged high voltage through the low resistance magnetic field generating coil 1 in a thyristor characteristic, for example, in the order of several tens of ms, and instantaneously magnetizes it.

Although such a circuit configuration itself is well known, according to the present invention, a charging voltage component composed of a resistor 11 connected in parallel to the thyristor 6a and resistors 12 and 13 connected in parallel to the magnetic field generating coil 1 is used. The voltage circuit 10 and the divided voltage of this voltage dividing circuit are used as inputs, and the low-pass filter 14 composed of the resistor 14a and the capacitor 14b and the breaker 3 are activated when the output voltage of the low-pass filter reaches a predetermined level. According to the above, a safety device including a charge interruption control circuit 15 for interrupting the charging operation of the charging circuit 5 and for sounding the buzzer 19 as an informing means is attached. The breaker and the charge interruption control circuit constitute the charge interruption means of the present invention.

The resistances 11 and 12 are 1 MΩ, the resistances 13 and 14 a are 100 kΩ, and the capacitor 14 b is 0.47 μF. The voltage dividing circuit 10 substantially functions as a voltage dividing circuit for the charging voltage when the parallel connection of the low resistance of about 5Ω is released due to the disconnection or disconnection of the magnetic field generating coil 1. Fulfill In order to prevent the high voltage from being directly applied to the capacitor 14b by reducing the output voltage when the thyristor 6a is turned on in the normal state, the resistor 12 and the resistor 13 are used for the output voltage component when the thyristor 6a is ignited. It constitutes a pressure circuit. The low-pass filter 14 has a high-cut characteristic that attenuates the divided voltage generated by the pulse-shaped resistors 12 and 13 generated when the thyristor 6a is ignited so as not to reach a predetermined level. On the other hand, when the magnetic field generating coil 1 is not connected, the charging voltage of the charging capacitor 5c is divided by the resistors 11, 12 and 13, and the divided voltage generated in the resistor 13 is supplied to the charging interruption control circuit 15 through the low pass filter 14. It At that time, the change in the charging voltage has a sufficiently low frequency component as compared with the applied voltage due to the ignition, and the low-pass filter 14 hardly attenuates the voltage. The charge interruption control circuit 15 is operated with the divided voltage of.

The discharge circuit 7 is provided with a contact monitoring circuit 20 for monitoring the welding of the contacts of the electromagnetic switch 7a. This contact monitoring circuit forms a charge stopping means in cooperation with the breaker 3 and operates at the initial stage of the operation of the charging circuit 5, so that when a predetermined voltage is detected in the discharge resistor 7b at the start of charging, the contact is detected. Is determined to be welded, the breaker 3 is actuated and the buzzer 29 as the notification means is rung.

The operation of the magnetizing device thus configured will be described with reference to FIG. In normal operation, the thyristor 6a is controlled to be fired when the charging capacitor 5c is charged with a predetermined high voltage (FIG. 2A) by the charging circuit 5, so that a voltage of about 2 kV is instantaneously applied to the magnetic field generating coil 1. Applied (FIG. 2B), a current corresponding to the resistance value instantaneously flows, and a magnetizing magnetic field is generated. This magnetizing magnetic field is generated in the charging cycle of the charging circuit 5, and magnetizes the magnetic material that is successively carried in.

During this time, the pulse voltage of about 2 kV applied to the magnetic field generating coil 1 is divided into about 1/10 by the resistor 13, further attenuated by the low-pass filter 14, and the output voltage thereof (see FIG. 2C). The voltage level and the pulse width are shown enlarged) and the predetermined level cannot be reached. If the magnetic field generating coil 1 is disconnected or disconnected, or if there are a plurality of magnetic field generating coils 1 and they float when switching is selected, the substantial short circuit between the resistors 12 and 13 due to the magnetic field generating coil 1 is released, and the charging voltage is reduced. The voltage is divided by about 1/20 in the resistor 13, and is input to the low-pass filter 14 and is input to the charge interruption control circuit 15 with almost no attenuation (the voltage level is enlarged and shown in FIG. 2D). As a result, the charge interruption control circuit 15 operates at the start of charging when the charging voltage rises to several tens of volts, shuts off the breaker 3 to stop the charging operation, and sounds the buzzer 19. Even when the magnetic field generating coil 1 is disconnected when the high voltage rises, the breaker 3 is naturally cut off by the same operation.

At the time of ending the operation of the apparatus, the contact of the electromagnetic switch 7a is turned on for a predetermined time in response to the operation end signal, and the residual voltage of the charging capacitor 5c is discharged. At that time, if a contact welding accident occurs due to repeated large current, the contact monitoring circuit 20 is activated by the voltage generated in the resistor 7b at the beginning of charging at the start of operation of the next magnetizing device, and the breaker 3 is cut off. The charging operation is stopped and the buzzer 29 is rung.

Instead of the above-described embodiment, the charging interruption means may be configured to interrupt the control operation of the charging ignition control circuit 5b without operating the breaker 3. Depending on the case, the resistor 12 may be omitted and the output voltage of the thyristor may be directly attenuated by the low-pass filter while maintaining the high voltage. Furthermore, the present invention eliminates the flywheel diode 2 in the above-described embodiment and replaces the thyristor 6a with a bidirectional thyristor, or connects the reverse direction diode to the thyristor 6a in parallel. , It is also applied to a demagnetizing device that generates a demagnetizing magnetic field by controlling the ignition so as to generate an attenuating AC voltage in a shorter period than the charging period.

[0017]

[Effect of device]

 As described above, according to the present invention, when the magnetic field generating coil is detached or disconnected, or a plurality of magnetic field generating coils are switched and selected during operation of the magnetic desorption device, the magnetic field generating coil is detected at a low charging voltage time point and automatically. High voltage generation is interrupted. Therefore, the electric shock of the worker or the arc generation in the coil changeover switch caused by the ignition control of the thyristor in the high impedance state or the conduction by the dv / dt characteristic thereof is prevented. Even if a high voltage is generated due to timing, it is immediately interrupted.

According to the second aspect, the resistance connected in parallel to the magnetic field generating coil is further configured as a voltage dividing circuit, whereby the input voltage of the low pass filter can be reduced.

[Brief description of drawings]

FIG. 1 is a diagram showing a circuit configuration of a safety device attached magnetic device according to an embodiment of the present invention.

FIG. 2 is a waveform diagram illustrating the operation of the device.

[Explanation of symbols]

 1 Magnetic field generating coil 3 Breaker 5c Charging capacitor

Claims (2)

[Scope of utility model registration request] 1. A firing control is performed between a charging circuit for charging a high voltage to a charging capacitor using a boosted commercial voltage as an input and a magnetic field generating coil so as to generate a magnetic field for magnetizing or demagnetizing after completion of charging. In the magnetic desorption device in which the thyristor is connected and the charging time is set longer than the ignition time of the thyristor, the high voltage output from the thyristor in the high impedance state due to the disconnection of the magnetic field generation coil is set. A safety device for preventing a voltage dividing circuit configured to divide the high voltage by a resistor connected in parallel to the thyristor and a resistor connected in parallel to the magnetic field generating coil, and a divided voltage of the voltage dividing circuit. A low-pass filter that receives as input, and a charge interruption procedure that interrupts the charging operation of the charging circuit when the output voltage of the low-pass filter reaches a predetermined level. Wherein the voltage dividing circuit has the predetermined voltage at the divided voltage at a rising time point of the high voltage in a state where the parallel connection of the magnetic field generating coils is released due to non-connection of the magnetic field generating coils. The low-pass filter is configured to reach a level, and has a high-cut characteristic capable of attenuating the output voltage when the thyristor is ignited in the connected state of the magnetic field generation coil so as not to reach the predetermined level. A safety device for a magnetic desorption device, which is characterized in that 2. A resistance connected in parallel to the magnetic field generating coil reduces the output voltage of the thyristor in the parallel connection state when the thyristor is ignited and inputs the output voltage to a low pass filter.
The safety device for a magnetic desorption device according to claim 1, further comprising a voltage dividing circuit for an output voltage.