JPS5870850A - High voltage power source of electric dust collector - Google Patents

Abstract

PURPOSE:To make it possible to certainly prevent the generation of heat and ignition due to dust, by detecting leakage current due to dust equal to corona discharge current level without error. CONSTITUTION:In a two-stage type electric dust collector having a charging part and a dust collecting part separately, output terminals D, E of a high voltage generating transformer 5 are exclusively provided to the charging part and the dust collecting part respectively and a smoothing capacitor is not provided to a high voltage integrated circuit for collecting dust or a high voltage power source circuit adjusted to such a value that a total capacity including the own capacity of the dust collecting part does not exceed a predetermined value is provided. In a control apparatus 14, the generation of leakage current between electrodes of the dust collecting part 2 is detected by a potential dividing circuit 12 from the variation of voltage waveform in the dust collecting part and, when this detection succeeds for a predetermined time, it is decided that leakage current due to foreign matters is generated to control the voltage of high voltage power source.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high-voltage power source for a two-stage electric industrial appliance that is divided into a charging section and a drainage section.

In general, electric dust collectors have a dust collecting section in which high voltage electrodes and earth electrodes face each other alternately with a slight gap in order to collect particles of charged substances using an electric field. It is generally accepted that the electric field strength of a rationally designed electric industrial dust generator will occasionally generate sparks between the electrodes during actual operation, and that substances that can ignite due to the spark energy should not be used in electric industrial dust generators. Excluded from the scope of application. However, apart from this, due to insufficient maintenance of electric industrial dust equipment, dust adhering to the electrode plate may straddle the gap between the high voltage electrode and the earth electrode, and the leakage current through the dust may cause the dust to heat up and ignite. In some cases, it is necessary to solve this problem as it is unique to the dust collector.

However, in conventional electrical industrial dust equipment, it is not recognized that it is important for safety to suppress leakage current due to dust adhering between the electrode plates.

Although there is a control means for detecting a short circuit between single Km poles and shutting down the power supply, it is conceivable that the waste may be heated and ignited before the short circuit occurs between the poles.

In other words, the inter-electrode plate leakage current that generates dust #C may be close to the corona discharge current for charging the dust-collecting material, whereas the conventional device uses a high-voltage power supply even if a discharge current of #C is supplied. A smoothing capacitor is provided in the high voltage rectifier circuit so as to supply a sufficiently large current without impairing the [iI characteristics of the voltage. Therefore, even if some leakage current occurs between the plates due to dust K, unless the corona discharge current is sufficiently large, there will be an abnormality between the plates.

The problem of garbage ignition accidents that could not be determined as normal has been identified.

This invention was made in view of the above circumstances.

An object of the present invention is to provide a high-voltage power source for an electric industrial appliance that can reliably prevent heat generation and ignition due to garbage by detecting leakage current equivalent to a corona discharge current due to garbage without error.

The electric industrial dust generator according to the present invention has a two-stage type in which a charging part that charges the dust particles and a dust collection part that collects the charged particles are separated, and the output terminal of the high voltage power transformer is connected to the charging part and the dust collecting part that collects the charged particles. A separate drawer is drawn out for the dust collection section, and the power supply configuration is such that the dust collection section rectifier circuit does not have a smoothing capacitor or has a smoothing capacitor at a lower capacity.

The present invention is characterized by a control device that determines leakage current due to dust from the mode of change in the rectified voltage waveform when interpolar leakage current occurs in the dust collecting section, and performs ignition prevention control such as adjusting the voltage load.

Hereinafter, one embodiment of this invention will be described in detail.

Figure 1 shows the electrode configuration of an electric industrial dust collector, which has a two-stage structure with a charging section 1 provided at the front stage in the direction of dust collection material feeding (indicated by the arrow) and a dust collection section 2 located at the rear stage. be done. The charging part 1 is supplied with a common electrode CIIJIK high voltage to the wire electrode A to generate corona discharge, and the conduit part 2 is supplied with a high voltage between the plate electrode B and the common electrode C to collect charged particles. do. A power supply circuit for supplying power to these electrodes has the configuration shown in FIG.

In FIG. 2, power is supplied from an AC line source 3 to a leakage transformer 5 for high voltage generation through all thyristors 4 that control the supply voltage by controlling the on/off ratio and firing angle. Unlike a general transformer, the leakage transformer 5 has a secondary half-wave rectifier circuit, but it prevents abnormal current from flowing into the primary side due to biased magnetism, and also prevents short circuits on the secondary side from flowing into the primary side.
It is possible to suppress the increase in t current, and the load voltage/current characteristics have a drooping curve, making it possible to self-control the corona current.

The secondary winding of the leakage transformer 5 is a tagged winding in which an output terminal for supplying power to the charging section 1 and an output terminal E for supplying power to the dust collection section 2 are respectively drawn out. The AC high voltage generated between the output terminal 1 and the common terminal 2 is rectified by the rectifying element 6, and is co-supplied between the electrodes A and 0 through the current limiting resistor 7. Similarly, the high voltage generated between output terminal E and terminal 2 is rectified by rectifying element 8, and current limiting resistor 9
be supplied between electrodes B and 0 through.

Here, a smoothing circuit consisting of a smoothing capacitor 10 and a current limiting resistor 11 is provided for the rectifier circuit that feeds power between the load portion WL poles A and 0, and the DC The power supply impedance is configured to be low to prevent voltage drop. On the other hand, the rectifier circuit that supplies power between the dust collection part electrodes B and C does not have a smoothing capacitor, but directly
Connected between L poles B and 0. In addition, the power consumption of the dust collecting section 2 is almost equal to zero during normal operation, and the power consumption is almost zero unless a smoothing capacitor is installed. Since the poles B and C themselves have a floating capacity of, for example, 10 to 10-9F in a small dust collector, sufficient smoothness is achieved.

However, it is permissible to add a smoothing capacitor to the extent that it does not interfere with the determination of leakage current in the dust collection section by a control device, which will be described later.

At the high pressure generation port wrVc with such a configuration, dust collection W5
Foreign objects with high resistance, such as dust, are located between the two electrode plates.

It is determined by the control device 14 using the ejection voltage of the voltage dividing resistor 12 of the high voltage voltage detecting voltage dividing resistors 12 and 13, and ignition is prevented by controlling the discrimination glass iris 4 and the like.

If we take out only the 1wk part 20 electric circuit, the equivalent circuit &C shown in FIG. 3 will be obtained. Here, 15 is a self-cancellation (city) possessed by the dust collecting part IF pole, and 16 is a high-resistance foreign object.The resistance value of the foreign object 16 is infinite, that is, the electrodes B and C
If there is no foreign object between them, the voltage waveform between electrodes B and C will be completely direct current. Ten thousand,! A foreign object straddles the poles,
If a leakage current occurs during that time, the resistance value of the foreign object 16 becomes a finite value, so the voltage between electrodes B and C will include ripples. This ripple content is the fourth
It is known that the characteristics shown in the figure are obtained.

Therefore, ripples are generated by monitoring the voltage between electrodes B and C as the detection output of the voltage dividing circuit 12.

In other words, it is possible to know that a leakage current has occurred in the skin electrode of the dust collection area, and by determining that this leakage current is caused by a foreign object, measures such as turning off the power and shutting down the system can be taken before there is a danger of the foreign object igniting. can be taken. Discrimination of foreign objects and ignition prevention control based on this leakage current detection are performed in 1. Control device 1j
14 K.

The control device 14 takes in the detected voltages from the voltage dividing circuits 12 and 13 as a digital signal through an analog-to-digital converter, performs digital processing using a microcombiner, etc., and controls the firing phase of the thyristor 40.
In addition to controlling the voltages of the charging section 1 and the dust collecting section 2, the thyristor 4 is controlled by determining the leakage current in the drain part due to foreign matter from the detection system signal of the voltage dividing circuit 12. This control device 14
Of course, it is possible to provide the same functions not only in the above-mentioned digital system but also in an analog/4G system.

The control device 14 determines the leakage current caused by the foreign object IC by the following operation.

First of all, if snow condensation occurs in the charged part or the dust collection part of the dust collector, this is not a safety problem, but since there is no smoothing capacitor between the dust collector electrodes or the capacity is small, the voltage waveform In addition, fluctuations in the power supply voltage sometimes cause voltage disturbances between the dust collection electrodes.In order to prevent these disturbances from being mistaken for ripples caused by foreign objects, the control device 14 Although the company recognized the occurrence of ripples, it did not immediately recognize the occurrence as an abnormality, and instead repeatedly conducted voltage tests to detect ripples.

Voltage disturbances and power supply voltage disturbances caused by sparks end in an extremely short time, whereas ripples caused by foreign objects continue for a relatively long time. Therefore.

The control device 1114 performs the detection 51 for a period sufficiently longer than the ripple generation time due to voltage disturbance due to power fluctuation during sparking.
i! Only when ripples are observed in all of the cases, it is determined that the ripples are caused by a foreign object.

Incidentally, the total canocity C between the dust collection electrodes, which is used to determine whether ripples are generated due to foreign matter, can be obtained from the following formula.

However, f is the power supply frequency, ■ is the chemical dust part voltage, i is the value of the leakage current to be detected, and n is the number of bits of digital data that is the resolution of the detection voltage in the control device 14.

As described above, in the present invention, in a two-stage electric industrial dust device in which a charging section and a dust collection section are separated, a voltage is applied to the charging section and the dust collection section from terminals drawn out individually from a transformer, Do not install a smoothing capacitor in the dust collection section, or use a capacitor with a very small amount of capacitance. It is possible to reliably prevent ignition accidents by identifying at each station whether a foreign object is straddling the object, which is distinguished from the occurrence of a foreign object.

[Brief explanation of drawings]

FIG. 1 is a diagram of the electrode configuration of a two-stage Kamiki drain duster, and FIG. 2 is a high-voltage power supply circuit diagram showing an embodiment of the present invention. FIG. 3 is an equivalent circuit diagram of the dust collection section multiplied by FIG. 2k. FIG. 4 is a ripple voltage characteristic diagram in FIG. 3. 1; Charged part, 2; Dust part. 5; Leakage transformer, lO; Smoothing capacitor, 12.13; Voltage dividing circuit, 14; Control device, 1
5: Self-capacity of the stain, 16: Leakage impedance. Patent applicant: Fuji'II Machinery Research Institute, Inc.
Person Patent Attorney Yoshihisa Narioka Figure 1 Figure 2 Figure 3 Figure 4 Figure 2πf-RC (F-Q)

Claims (1)

[Claims] In a two-stage electric industrial dust collector in which a charging section and a dust collection section are separated, the output terminals of the high voltage generation transformer are dedicated to the charging section and the dust collection section, respectively, and The high-voltage rectifier circuit for the part shall not be equipped with a smoothing capacitor, or a high-voltage power supply circuit shall be provided whose m-response to the self-capacity of the dust collecting part does not exceed a predetermined value. A control device is installed that detects the occurrence of leakage current between the electrodes in the dust collection section from fluctuations in the voltage waveform at the bottom, and when this detection continues for a predetermined period of time, determines that the leakage current is caused by foreign matter and controls the paper power supply voltage. A high-voltage power supply for electrical industrial equipment.