JPH03272437A - Particle counter - Google Patents

Abstract

PURPOSE:To improve a measuring accuracy by providing an orifice type flowmeter for measuring the quantity of liquid flowing to a particle counter and a flowrate regulator for regulating a flow rate in response to the pressure difference of the flowmeter. CONSTITUTION:A particle counter 3 measures the quantity of dust in oil of an oil-immersed electric device 1.The counter 3 is so regulated by correction curves of the difference (h) and the flow rate of an orifice type flowmeter 5, obtained in advance that a flowrate regulator 4 becomes a pressure difference (h) to easily feed at a suitable flow rate thereto. Then, since the difference (h) of the counter 5 is varied if the temperature of oil is altered due to variations in the atmospheric temperature, a load, etc., the difference (h) is regulated by the regulator 4. Thus, the measuring accuracy of the counter can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a particle counter for measuring the amount of dust in a liquid, and particularly to a flow meter for a particle counter for on-line measurement.

[Conventional technology]

For example, at manufacturing sites for semiconductors and oil-filled electrical equipment,
In order to reduce defective rates and improve reliability, the amount of dust in water, solvents, machine oil, and insulating oil is controlled.

A particle counter is mainly used to measure the amount of dust in a liquid, and is measured by the following method.

First, in the online method, liquid is collected in a particle measurement container, the container is placed in a particle measurement chamber, and the pressure is adjusted according to the viscosity and specific gravity of the liquid so that a certain amount of liquid flows through a part of the sensor per unit time. This method measures the number of particles in the liquid by adjusting the inside of the chamber. This method has a problem in that it is difficult to constantly monitor the influence of dust attached to the container from which the liquid is collected and the amount of dust in the liquid.

Therefore, by connecting a particle counter to a part of the liquid flow path and adjusting the flow rate so that a certain amount of liquid flows through a part of the sensor per unit time, it is possible to measure the amount of dust in the liquid without collecting it into a container. There is an online method that can be used to measure it. However, many of the flowmeters used in the online method are float type, which are made specifically for water. Therefore, when measuring the number of particles in a liquid with a viscosity or specific gravity different from that of water, the indicated value of the flowmeter must be calibrated using a measuring cylinder or the like before use.

[Problem to be solved by the invention]

In the conventional online particle counter as described above, there is no particular problem when the measuring liquid is water or when measuring the amount of dust in a liquid whose temperature is controlled to be constant, even if the liquid is not mercury.

However, when measuring the amount of dust in insulating oil used in oil-filled electrical equipment, for example, the viscosity and specific gravity of the insulating oil are as shown in Figures 4 and 5.
As shown in the figure, it has characteristics that vary greatly depending on temperature. In addition, the oil temperature in oil-filled electrical equipment changes due to changes in outside temperature and load, so even if you adjust the flow rate flowing to a part of the sensor at a certain temperature, if the oil temperature changes, the viscosity and specific gravity of the insulating oil will change. There was a problem in that the number of particles in the insulating oil per unit flow rate could not be accurately measured because the flow rate per unit time changed.

The present invention was made to solve such problems, and an object of the present invention is to provide a particle counter with high measurement accuracy by flowing a certain amount of liquid through a part of the sensor of the particle counter.

[Problem to be solved by the invention]

The particle counter according to the present invention uses an orifice type or bellows as a flow meter that is not affected by the viscosity or specific gravity of the liquid in order to control the amount of liquid flowing through a part of the sensor.

[Effect]

The particle counter in this invention always maintains a constant amount by controlling the flow rate so that the pressure difference at the orifice remains constant even if the liquid temperature in the device changes and the amount of liquid flowing through a part of the sensor changes. Flow liquid to part of the sensor.

In another embodiment of the invention, a bellows is used to deliver a volume of liquid to a portion of the sensor.

〔Example〕

FIG. 1 shows an embodiment of the present invention, in which A is a configuration diagram and the mouth is a sectional view of an orifice. 1 is an oil-filled electrical device such as an oil-filled transformer or an accelerator, 2 is a pump for sending insulating oil to a particle counter 3, and 3 is a light scattering device for measuring the amount of dust in the oil of the oil-filled electrical device 1. A new optical particle counter, 4 is a regulator for adjusting the flow rate,
5 is an orifice type flow meter.

In the apparatus for measuring particles in insulating oil configured as described above, the pressure difference is adjusted by the regulator 4 so that an appropriate flow rate flows to the particle counter based on the pressure difference of the orifice type flowmeter 5 and the calibration curve of the flow rate determined in advance. The flow rate of the particle counter 3 is preferably about 100 cc/min from the viewpoint of resolution.

At this time, if the measurement time of the particle counter is set to 1 minute, the number of particles per 100 cc of insulating oil can be determined.

Next, if the oil temperature changes due to changes in outside temperature or load fluctuations,
Since the pressure difference of the orifice flowmeter changes, the pressure difference can be adjusted using a regulator.

In the above embodiment, the case where the regulator is adjusted manually is described, but if the regulator is controlled by the pressure signal of the orifice type flowmeter, the number of particles in the insulating oil can be constantly monitored unattended. .

Fig. 2 shows another embodiment for sending a fixed amount to the particle counter 3, in which piping is connected to the oil-filled electrical equipment 1 with a flexible tube 6, and check valves 8a and 8b are installed to prevent backflow of oil. Move the attached bellows 7 left and right (arrow El) A at a constant speed using a motor or the like.

By moving it in the direction B), a fixed amount of liquid can be sent to the particle counter 3 regardless of the viscosity or specific gravity of the insulating oil.

FIG. 3 shows another embodiment in which the bellows 7 is used in a flowmeter, in which the position of the bellows 7 is detected by electric or mechanical limit switches 9a, 9b, and the operating time of the limit switch is measured by a timer 11. By doing so, the amount of liquid flowing into the particle counter 3 can be measured.

Incidentally, in the above explanation, the case where the amount of dust in oil-filled electrical equipment is measured has been explained, but it goes without saying that the present invention can also be used in other machine-like devices.

〔Effect of the invention〕

As explained above, this invention has a simple structure in which an orifice-type flow meter and a bellows are attached, so even if the viscosity or specific gravity of the liquid changes, the particle counter can prevent the liquid from coming into contact with the outside air or being released to the outside. The amount of fluid that flows can be controlled.

[Brief explanation of drawings]

FIG. 1A is a block diagram showing one embodiment of the present invention, FIG. FIG. 4 is a diagram showing the temperature characteristics of the kinematic viscosity of the liquid, and FIG. 5 is a diagram showing the temperature characteristics of the specific gravity of the liquid. In the figure, 1 is oil-filled electrical equipment, 2 is a pump, 3 is a particle counter, 4 is a liquid volume regulator, 5 is an orifice type flow meter, 7 is a bellows, 8a, 8b are check valves, 9a, 9b are limits The switch ]1 is a timer. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (3)

[Claims] (1) In a particle counter connected to a part of the liquid flow path to measure the amount of dust in the liquid, an orifice type flowmeter for measuring the amount of liquid flowing to the particle counter;
A particle counter characterized by being equipped with a flow rate regulator for adjusting the flow rate according to the pressure difference of the orifice type flowmeter. (2) A particle counter connected to a part of a liquid flow path for measuring the amount of dust in the liquid, characterized in that the particle counter is equipped with a bellows that sends a fixed volume of liquid to the particle counter. (3) A particle counter connected to a part of the liquid flow path for measuring the amount of dust in the liquid, which is equipped with a bellows, and a limit switch and a timer for measuring the travel time of the bellows. counter.