JPH07161534A - Static induction machine - Google Patents

Abstract

PURPOSE:To estimate the quantity of static electricity generated by fluid charging in a static induction machine accurately and to retard the generation of static electricity if there is any possibility of electrostatic trouble. CONSTITUTION:A relaxation tank 8, a fluid charge generating section 9, a static electricity detecting section 10, and a current meter 12 are arranged sequentially in the vicinity of the upper part of a tank 2 and a part of insulating fluid 1 is fed through them into a cooling circulation circuit 5 from above the tank 2. At a fluid charge generating section 9, an insulating liquid 1 is fluidized while applying an AC electric field to a duct 19 between the electrodes 17 coated with same insulator 16 as that being employed in the static induction machine. A comparing section 25 compares the fluid current measured at the detecting section 10 is compared with a value allowable under the conditions of current velocity, temperature, and AC electric field of the duct 19 and delivers an alarm if the measured value is higher than the allowable value. A mixing tank 33 filled with the insulating liquid 1 containing a charge retardant is installed in a bypass circuit 34 in the way of the cooling circulation circuit 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling-type static induction machine in which an insulating liquid is forcibly circulated, and more particularly, to a static induction machine having a function of monitoring and suppressing static electricity during operation.

[0002]

2. Description of the Related Art Generally, it is a well-known phenomenon that static electricity is generated at a contact surface with a solid when an insulating liquid flows, that is, flow charging occurs. In a static induction machine in which a winding is housed in a tank and filled with an insulating liquid, the insulating liquid is circulated between an external cooler and the tank for the purpose of cooling the winding, which is a heating element. It is known that the flow charging phenomenon of A forced cooling oil-filled transformer is a typical example of such a static induction generator. In this type of transformer, static electricity is generated at the interface with the structure that makes up the transformer due to the flow of insulating oil, and if there is a large amount of static electricity, electrostatic discharge occurs, which may lead to dielectric breakdown of the transformer. There is a nature. Therefore, it is important for the operation and maintenance of the transformer to constantly monitor the static electricity amount during operation and evaluate the static electricity failure. Conventionally, since it is not possible to directly measure the amount of static electricity generated inside a transformer, as a means for estimating it, an external static electricity monitoring device is installed as shown in Japanese Patent Publication No.55-24686, and the static electricity amount is constantly maintained during operation. It is proposed to monitor. That is, the insulating oil is made to flow on the metal electrode surface surrounded by the insulator that has been treated the same as the transformer body,
The static electricity monitoring device for detecting the generated static electricity as the ground current of the metal electrode is arranged in a part of the cooling pipe or in the bypass circuit.

[0003]

According to the conventional means for monitoring static electricity, the flow velocity of the insulating oil is set to be the same as that in the transformer, but other internal conditions of the transformer that affect the flow electrification, namely, The temperature of the insulating oil and the AC electric field applied to the insulating oil are not particularly taken into consideration, and there is a problem in that the amount of static electricity generated inside the actual transformer is not accurately estimated. Also, in the unlikely event that static electricity is generated and there is a risk of static electricity failure, it is effective to reduce the flow rate of insulating oil inside the transformer in order to suppress static electricity generation without stopping the operation. However, lowering the flow velocity means reducing the flow rate, which leads to a reduction in cooling performance, that is, a reduction in load capacity of the transformer. Therefore, it is also required to prevent electrostatic damage without reducing the load capacity of the transformer.

An object of the present invention is to accurately estimate the amount of static electricity generated by flow electrification inside a static induction electric device, and to suppress the amount of static electricity generated when there is a risk of electrostatic damage. It is to provide electric appliances.

[0005]

SUMMARY OF THE INVENTION The present invention is a static induction device for forcibly circulating and cooling an insulating liquid, wherein a static electricity monitoring device comprising a static charge generation part and a static electricity detection part provided downstream thereof is provided as a static induction device. Placed close to the top of the tank, the static charge generator of the static electricity monitor is covered with the same insulating material used in the static induction electric tank, and static induction is applied between the electrodes to which an AC electric field is applied. It is designed to make the insulating liquid flowing from the upper part of the tank of the electric appliance flow.Furthermore, a means for measuring the temperature and flow velocity of the insulating liquid is provided, and the tolerance determined by the magnitude of the AC electric field of these and the flow electrification generation part A comparison / determination unit is provided which compares the static electricity generation amount with the static electricity generation amount measured by the static electricity detection unit of the static electricity monitoring device and issues a warning when the latter value is larger than the former value.
Further, a mechanism is provided for injecting an insulating liquid containing a high-concentration antistatic substance in the middle of the insulating liquid cooling circulation circuit when a warning is issued.

[0006]

According to the present invention, the static charge generating portion of the static electricity monitoring device causes static charge in consideration of the conditions closer to the inside of the static induction electric device, that is, in addition to the flow velocity, temperature and AC electric field, and the static charge generation amount is determined. Because it measures with the static electricity detection section,
It is possible to accurately estimate the flow charge inside the static induction electric device. Further, the comparison / determination unit can determine whether or not there is a possibility of occurrence of electrostatic trouble, and if it is judged that there is a possibility of occurrence of electrostatic trouble, the insulating liquid added with the antistatic substance is injected. The generation of static electricity inside the stationary induction device can be suppressed, and electrostatic discharge due to charge accumulation or a dielectric breakdown accident resulting therefrom can be prevented.

[0007]

EXAMPLES The present invention will be described below based on examples.
FIG. 1 is a block diagram of a main body and an external part of a static induction generator showing an embodiment of the present invention. In FIG. 1, an iron core 3 and windings 4 wound around the iron core 3 are provided inside a tank 2 filled with an insulating liquid 1.
Is stored in the tank 2, and a cooler 6 and a pump 7 are provided outside the tank 2 via a cooling circulation circuit 5 for cooling the iron core 3 and the windings 4.
The static electricity monitoring device 1 is provided between the upper part of the tank 2 and the cooling circulation circuit 5 and is arranged in the vicinity of the upper part of the tank 2 and includes a relaxation tank 8, a flow electrification generation part 9 and an electrostatic detection part 10.
1, the flowmeter 12 is arranged in this order, and a part of the insulating liquid 1 in the upper part of the tank 2 flows into the cooling circulation circuit 5 through them. The amount of the insulating liquid 1 flowing into the static electricity monitoring device 11 is adjusted by changing the opening / closing amount of the valve 13 and the valve 14 provided in the cooling circulation circuit 5. On the other hand, FIG. 2 shows a specific configuration diagram of the static electricity monitoring device 11 including the flow charge generation unit 9 and the static electricity detection unit 10. In FIG. 2, the flow charge generation unit 9
The electrode 17 covered with the same insulator 16 as that used in the main body of the stationary induction device is arranged to face each other in the grounded storage container 15, and the electrode 17 is fixed by the support insulator 18. At the same time, the insulating liquid 1 is allowed to flow through the duct 19 facing the insulator 16. Further, an AC high voltage is applied to the one electrode 17a by the AC power supply device 20 through the high voltage terminal 21, and the other electrode 1a
7b is grounded, and a predetermined AC electric field is applied between the electrodes 17, and the magnitude of this AC electric field is converted into an electric signal in the AC power supply device 20 and shown in FIG. In this way, the comparison and determination section 23 is loaded. Further, the storage container 15 is provided with a temperature sensor 24 for detecting the temperature of the insulating liquid 1. The temperature measured here is converted into an electric signal and is compared through a signal line 25 as shown in FIG. It is adapted to be taken into the determination unit 23. The flow charge is generated in the duct 19 portion in FIG. 2, and the charged insulating liquid 1 flows into the static electricity detection unit 10 provided downstream of the flow charge generation unit 9 and is insulated from the surroundings by the insulator 26. It stays in the relaxation container 27, where the charged electric charge in the insulating liquid 1 leaks to the ground through the ammeter 28. The current measured at this time, the so-called
The magnitude of the flowing current is converted into an electric signal by the ammeter 28 and taken into the comparison / determination unit 23 through the signal line 29 as shown in FIG. Further, in FIG. 1, the velocity meter 12 measures the value converted into the velocity in the duct 19, and the measured value is converted into an electric signal and is compared through the signal line 30 as shown in FIG. It is adapted to be taken into the determination unit 23. As described above, the comparison / determination unit 23 shown in FIG. 1 fetches the magnitude of the AC electric field in the duct 19, the temperature and flow velocity of the insulating liquid 1, and the magnitude of the flowing current as information, and the duct 19 pre-insulates the insulation property. The allowable value of the flowing current determined by the temperature and the flow velocity of the liquid 1 and the magnitude of the alternating electric field, that is, the magnitude of the flowing current satisfying the condition that the static induction of the static induction electric device main body due to the flow charging does not occur is input, The comparison / determination unit 23 has a function of comparing the allowable value of the flowing current determined by the temperature and flow velocity of the insulating liquid 1 and the magnitude of the alternating electric field with the measured value, and issuing an alarm when the latter value is larger than the former value. There is. On the other hand, in the middle of the cooling circulation circuit 5 between the tank 2 and the pump 7, a bypass is provided in which a mixing tank 33 filled with the insulating liquid 1 containing a high-concentration antistatic substance is placed via valves 31 and 32. A circuit 34 is provided.

In the configuration of the present invention shown in FIGS. 1 and 2, the process of the generation of the flow charge in the duct 19 of the flow charge generation unit 9 and the measurement of the static electricity amount in the static electricity detection unit 10 is as follows. First, the insulating liquid 1 that has flowed from the upper part of the tank 2 into the relaxation tank 8 is in a substantially non-charged state due to the neutralization of positive and negative ions and the leakage of charges to the ground. Flowing into the duct 19,
At this time, charge separation, that is, an electric double layer is formed at the interface with the insulator 16, and the insulator 16 and the insulating liquid 1 are formed.
Are charged with opposite polarities. For example, it is known that in oil-filled transformers, mineral oil, which is an insulating liquid, is positively charged, and insulators such as pressboards are negatively charged. The insulating liquid 1 thus charged to one of the polarities flows into the static electricity detection unit 10 on the downstream side and stays in the relaxation container 27. At this time, the product of the volume resistivity and the dielectric constant of the insulating liquid 1 is obtained. If the capacity of the relaxation container 27 is set so as to stay sufficiently longer than the relaxation time represented, almost all the charges in the insulating liquid 1 will leak to the ground through the ammeter 28, and this measured flow The magnitude of the current indicates the amount of static electricity generated in the duct 19, that is, the magnitude of the flow charge. By the way, the factors that control the magnitude of the flow charge inside the static induction device are the operating conditions, that is, the type of insulating liquid, the type of insulating material, the temperature and flow velocity of the insulating liquid, and the interface between the insulating liquid and the insulating material. It is the magnitude of the alternating electric field. In the duct 19 of the flow electrification generation unit 9 of the present invention, the type of insulating liquid, the type of insulating material, the temperature and flow velocity of the insulating liquid, and the magnitude of the AC electric field applied to the interface between the insulating liquid and the insulating material are statically induced. Since it can be set to be almost equal to the operating condition inside the electric appliance, the magnitude of the flowing current measured by the static electricity detection unit 10 can be said to accurately estimate the magnitude of the flowing electric charge inside the static induction electric appliance, though relatively. . Further, the comparison / determination unit 23 has a temperature, a flow velocity, an AC
The relationship between the condition of the electric field and the allowable value of the flowing current, that is, the value lower than the lower limit value of the flowing current with a margin under the condition that electrostatic discharge occurs inside the static induction device is input, and the measured flowing current is When the value is larger than this value, the comparison / determination unit 23 issues an alarm, so that it is possible to predict the occurrence of electrostatic discharge due to flow electrification inside the stationary induction machine. Further, when an alarm is issued by the comparison / determination unit 23, the valves 31 and 32 are opened to inject the insulating liquid 1 ′ containing the antistatic substance in the mixing tank 33 into the insulating liquid 1 of the cooling circulation circuit 5. As a result, the insulating liquid 1 containing the charge suppressing substance flows into the tank 2, and the charge suppressing substance suppresses the flow charge generated inside the main body such as the iron core 3 and the winding 4. For example, benzotriazole is a typical example of the antistatic substance in mineral oil used in oil-filled transformers.

[0009]

According to the present invention, it is possible to accurately estimate the magnitude of flow electrification inside a static induction electric generator, predict the occurrence of electrostatic discharge, and cool the electrostatic discharge if it is suspected. It is possible to suppress the generation of flow electrification inside the static induction electric device by the injected electrification suppressing substance without reducing the flow rate of the circulating insulating liquid. Therefore, it is possible to prevent a dielectric breakdown accident from occurring due to the occurrence of electrostatic discharge due to flow electrification without impairing the cooling performance in the static induction machine.

[Brief description of drawings]

FIG. 1 is a block diagram of a static induction generator showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a static electricity monitoring device according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Insulating liquid, 2 ... Tank, 4 ... Winding, 5 ... Cooling circulation circuit, 8 ... Relaxation tank, 9 ... Flow electrification generation part, 10 ... Static electricity detection part, 11 ... Static electricity monitoring device, 12 ... Velocity meter, 1
6 ... Insulator, 17 ... Electrode, 20 ... AC power supply device, 23 ...
Comparison / determination unit, 24 ... Temperature sensor, 27 ... Relaxation container, 28
... ammeter, 33 ... mixing tank.

Claims (5)

[Claims] 1. A static electricity monitoring device for forcibly circulating an insulating liquid between a tank accommodating a winding wire and an external cooler via a cooling pipe, and for monitoring static electricity generated by flow electrification outside the tank. In the static induction equipment provided,
The static electricity monitoring device comprises a static charge generation unit and a static electricity detection unit provided downstream of the flow static electricity generation unit, and is arranged between the tank and a cooling pipe close to the upper portion of the tank. . 2. The static electrification generating section of the static electricity monitoring device according to claim 1, wherein electrodes facing each other are covered with the same insulator as the inside of the tank, and a duct through which an insulating liquid flows between the electrodes. A static induction generator composed of a high-voltage device that applies an AC voltage to one electrode and grounds the other electrode. 3. The static induction machine according to claim 1, further comprising a relaxation tank which is grounded between the static electricity monitoring device and an upper portion of the tank and in which an insulating liquid is retained. 4. The temperature and flow velocity of an insulating liquid are measured downstream of the static electricity monitoring device according to claim 1, and these values and an AC electric field applied between electrodes of the flow electrification generating unit are taken in as information, A comparison determination unit that compares the allowable value of the static electricity generation amount that is determined in advance with the static electricity amount measured by the static electricity detection unit and issues a warning when the latter value is larger than the former value is provided. Stationary induction device. 5. The function of injecting an insulating liquid containing a high-concentration antistatic substance, which is stored in advance, into the insulating liquid of a main body of a static induction electric device when a warning is issued by the comparison / determination unit according to claim 1. A static induction electric device having the cooling pipe in the middle thereof.