JPS6139103B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a power supply device for an electrostatic precipitator.

Conventionally, as a power supply device for an electric precipitator for air conditioning,
Many are used that apply a method of controlling the application of charging voltage by detecting the circuit current supplied to the electrostatic precipitator. This current detection control method uses, for example, the constant current characteristics of a saturable reactor to temporarily lower the charging voltage due to the drooping characteristics of the saturable reactor when the supply current increases, or to set a certain time limit. Charging is stopped by interrupting the circuit. With a power supply device to which such a system is applied, for example, when the electrode plate of an electrostatic precipitator becomes dirty, the charging voltage can be reduced or cut off by increasing the supply current.

However, in the conventional device, the response is slow, and even though the variable reactor has a drooping characteristic, it returns according to this characteristic, so when a discharge such as a spark occurs, this discharge lasts for a relatively long time. As a result, depending on the type of accumulated dust, sparks caused by the discharge may ignite and cause a fire. According to experiments conducted by the present inventors, it has been confirmed that dust with a composition of 25% carbon, 30% oil, and 45% inorganic is most likely to ignite, and that most ignition occurs when the application time exceeds 1 second. Ta.

The present invention has been made focusing on the above circumstances,
The purpose of this is to shorten the response time to less than one second by adopting a voltage detection method as a power supply control means, to reliably prevent ignition of dust, and to be able to reliably detect only abnormalities. The object of the present invention is to provide a power supply device for an electrostatic precipitator that is highly safe and has reliable control operations.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a circuit configuration diagram of a power supply device for an electrostatic precipitator in the same embodiment.

This device includes a power supply main body 2 that generates a charging voltage from the output (commercial power) of an AC power source (not shown) and supplies it to an electrostatic precipitator 1, and a current detection control circuit 3.
, a voltage detection control circuit 4 provided parallel to this current detection control circuit 3, and a power cutoff circuit 5.
It is composed of.

The power supply main body 2 first guides commercial power through a power switch 21 to a power control element 22 consisting of a triac, and performs switching by this power control element 22. Then, the output is led to the high voltage transformer 24 through the AC side time-limiting resistor 23, and the transformer 24 and the voltage doubler rectifier circuit 25 generate 12KV.
A DC high voltage of 6KV is generated and these voltages are supplied to the electrostatic precipitator 1 as charging voltages.

Further, the current detection control circuit 3 detects the output current of the voltage doubler rectifier circuit 25 via a detection level setting resistor 31 with a current detection section 32; When it is detected that a predetermined level has been exceeded, the gate signal generated from the control circuit 33 is turned off to put the power control element 22 into a non-operating state.

Now, as shown in FIG. 2, for example, the voltage detection control circuit 4 includes a constant voltage diode 41, a detection transistor circuit 42, and a detection level setting resistor 43.
It is composed of a voltage drop detection section 44 equipped with a gate signal stop control circuit section 45, and a recovery control circuit section 46. Gate signal stop control circuit section 45
, a transistor circuit 47 and two relay circuits 4 that become conductive from the detection output of the voltage drop detection section 44;
8, 49, and delay circuits 50 each consisting of a capacitor and a resistor. In addition, the return control circuit section 46 includes a timer circuit 5 which includes a delay relay that performs a timing operation when the relay circuit 49 is energized.
1, and the detection transistor circuit 47 of the voltage drop detection section 44 is forcibly made conductive when the timer circuit 51 times out. Note that the time measured by the timer circuit 51 is set to, for example, about 10 seconds.

Next, the operation of the device configured as above will be explained. During steady charging, if the insulation resistance decreases due to the accumulation of dust, for example, and this causes continuous spark discharge or short circuit, and the charging voltage abnormally decreases as shown in FIG. The voltage applied to both ends of transistors 43 and 52 decreases, and when this voltage becomes lower than the detection level L1 (4KV), the transistor circuit 42 is turned off.
As a result, the transistor 47 of the gate signal stop control circuit section 45 is first turned on, thereby exciting the relay circuit 48 and closing its contact 48a. By closing this contact 48a, the resistance 5
A current flows into the capacitor 55 through the capacitors 3 and 54 to charge the capacitor 55, and when the charging voltage exceeds a predetermined value, the transistor 56 is turned on. In other words, the transistor 56 is connected to the delay circuit 50 consisting of the capacitor 55 and resistors 53 and 54.
Due to the action of , it turns on when an abnormal drop in charging voltage continues for a certain period of time. Here, the delay circuit 5
The delay time of 0 is set to 0.5 to 0.7 seconds. Therefore, even if a temporary voltage drop (generally several μs) occurs due to a spark as shown in FIG. 3B, this drop will not be immediately detected as an abnormality.

When the transistor 56 is turned on, the relay circuit 49 is excited and its contact 49a is closed, and as a result, the power control element 22 of the power supply main body 2
The gate signal supply path to is opened. Therefore, the power control element 22 is turned off, and as a result, the charging voltage becomes zero. However, electric dust collector 1
The supply of charging voltage to is reliably stopped within one second after an abnormality occurs. Therefore, even if the dust is ignitable, such as in a parking lot, ignition will not occur.

By the way, when the relay circuit 49 is excited, the contact 49b is closed, and therefore the timer circuit 51 of the return control circuit section 46 starts a timing operation. Then, when 10 seconds have elapsed, the contact 51a closes and the transistor circuit 42 is turned on, and this forced on control causes the transistor circuits 47 and 56 to turn on.
are turned off, and each relay circuit 48, 4 is turned off.
9 is demagnetized. As a result, the contact 49a returns to the closed state, thereby causing the power control element 22 to communicate and supplying the charging voltage to the electrostatic precipitator 1 again.

However, at this time, there were still abnormalities such as short circuits,
When the charging voltage is below the detection level L1, the transistors 42 and 47 are turned off and on, respectively, and the relay circuit 48 is excited.As a result, the relay circuit 48 is activated after a certain period of time (0.5 to 0.7 seconds) determined by the delay circuit 50. 49 is excited, the power control element 22
The gate signal supply path to is opened. Therefore, the supply of charging voltage is stopped again, for example, as shown in FIG. 3C. At the same time, the timer circuit 51
starts counting, and when 10 seconds have elapsed, the charging voltage is supplied. From then on, as long as the abnormal condition continues, the charging voltage supply is stopped and restored repeatedly.

By the way, during the repetition of the above-mentioned stop and return, current is side-flowed to the temperature sensing circuit 5a of the power cutoff circuit 5 during each stop period, and heat is stored in the temperature sensing element. When the temperature sensing element reaches a predetermined temperature due to this heat accumulation, the thermal reed switch is turned on and the AC power circuit of the power supply main body 2 is cut off. is maintained. That is, the repetition of the above-mentioned stop and return causes the above-mentioned temperature sensing circuit 5a to
When the predetermined time Ts continues, the power supply main body 2 regularly cuts off the power supply operation as shown in FIG. 3D. At this time, the time until the above-mentioned shut-off is set to about 60 seconds.

Note that during the repeated stop and return period, when dust etc. are removed by ventilation and spark discharge and the normal state is restored, the charging voltage returns to a steady value as shown in FIG. Charging takes place.

In this way, a series of charging voltage supply controls are performed by the voltage detection control circuit 4.

On the other hand, if the current supplied to the dust collector increases above a predetermined value due to dirt on the electrode plate of the electric dust collector, the increase in current is detected by the current detection control circuit 3 even if the charging voltage has not decreased below 4KV. is,
This circuit 3 opens the gate signal stop control circuit section to the power control element 22. As a result, the power control element 22 is turned off, and the supply of charging voltage is stopped. Thereafter, the return and stop are repeated at regular intervals. Then, during this repeated period, the temperature sensing circuit 5a of the power cutoff circuit 5 operates, and when the heat storage temperature reaches a predetermined value, that is, after approximately 60 seconds have elapsed, the charging voltage supply operation of the power supply main body 2 is stopped. .

In this way, in this embodiment, when the current value increases due to dirt on the electrode plate of the electrostatic precipitator, etc., the current detection control circuit 3 reliably shuts off the current value before it reaches a dangerous value. Therefore, it can be used safely, and if it is cleaned at that time, it can always be used efficiently. Furthermore, in this embodiment, in addition to the current detection control described above, the supply of the charging voltage is controlled by detecting a drop in the charging voltage and controlling the power control element by switching, so that the charging voltage can be stopped quickly within 1 second. As a result, even when handling dust that has a risk of ignition, the power supply can be reliably stopped before ignition occurs. Therefore, a device with even higher safety can be provided. In addition, in this embodiment, the power supply stop time when an abnormality occurs is set to 0.5 to 0.7 seconds by intervening the delay circuit 50, so that short-term discharges such as sparks other than when an abnormality occurs are immediately abnormal. Therefore, accurate detection can be performed. Furthermore, since the power supply main body includes a high-voltage capacitor, it takes time to start up when the power is turned on. For this reason, if the detection time is set to a short time, it may not be possible to start up in just one time. However, in this embodiment, although the detection time is set to 0.5 to 0.7 seconds as described above,
It can be stood up by the return operation.

Note that the present invention is not limited to the above embodiments. For example, in addition to using a temperature sensing element and a thermal reed switch, a counter may be used as the power cutoff circuit 5, and the counter counts the number of repetitions of stopping and returning, and stops the power supply when a predetermined number of times has been reached. You may also do so. In this way, it is possible to shift to a stop more accurately than when using a temperature sensing element or the like. In addition, the circuit configuration of the voltage detection control circuit, the configuration of the power supply device body, etc. can be modified in various ways without departing from the gist of the present invention.

As detailed above, according to the present invention, the power supply is controlled by adopting a voltage detection method and controlling the power control element by switching based on its detection output, thereby reducing the response time to less than 1 second. Thus, it is possible to provide a power supply device for an electrostatic precipitator that can reliably prevent ignition of dust and can reliably detect only abnormalities, thereby providing high safety and reliable control.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of a power supply device for an electrostatic precipitator according to an embodiment of the present invention, Fig. 2 is a circuit diagram showing the main parts of the device, and Fig. 3 is an operation of the power supply device shown in Fig. 1. It is a voltage change characteristic diagram for use in explanation. 1... Electrostatic precipitator, 2... Power supply unit, 3...
...Current detection control circuit, 4...Voltage detection control circuit,
5... Power cutoff circuit, 44... Voltage drop detection section,
45...Gate signal stop control circuit section, 46...Return control circuit section, 50...Delay circuit, 51...Timer circuit.

Claims (1)

[Scope of Claims] 1. A power supply main body that generates a charging voltage from an AC power output by a power supply circuit having a power control element and supplies it to an electrostatic precipitator, and a power supply unit that detects the charging voltage in a supply path to the electrostatic precipitator. a voltage detection and stop control circuit that controls switching of the power control element to stop supplying the charging voltage to the electrostatic precipitator when the charging voltage continuously drops below a predetermined voltage for a first period of time; A return control circuit that restores the supply of the charging voltage when a second time period has elapsed after the stop; and a return control circuit that restores the supply of the charging voltage when the voltage detection stop control circuit and the return control circuit have repeatedly performed the supply of the charging voltage for a third time or more; A power supply device for an electrostatic precipitator, comprising a cutoff circuit that regularly cuts off the supply of charging voltage to the precipitator. 2. A power supply main body that generates a charging voltage from an AC power output by a power circuit having a power control element and supplies it to the electrostatic precipitator; a voltage detection stop control circuit that controls switching of the power control element to stop supplying the charging voltage to the electrostatic precipitator when the voltage drops below a predetermined voltage continuously for a period of time; a return control circuit for restoring the supply of the charging voltage when the period has elapsed; and a return control circuit that detects the current supplied to the electrostatic precipitator and stops the supply of the charging voltage to the electrostatic precipitator when this current increases to a predetermined value or more. a current detection stop control circuit; a current return control circuit for restoring the supply of charging voltage when a fourth period of time has elapsed after the current detection stop control circuit stopped supplying the charging voltage; and repeating the return by the return control circuit, or repeating the stop by the current detection stop control circuit and the return by the current return control circuit.
1. A power supply device for an electrostatic precipitator, comprising: a cutoff circuit that regularly cuts off the supply of charging voltage to the electrostatic precipitator when the charging voltage is maintained for a period of time or longer.