KR950013422B1 - A sliding comtactor of electric machines - Google Patents

Abstract

No content.

Description

Sliding contactor of electric equipment

1A is a plan view of a movable contact portion of a circuit breaker to which the present invention is applied.

1b or side view of the movable contact portion of FIG. 1a.

2 is an electron micrograph showing the metal structure of the sliding contact portion of FIG.

3 is a graph showing a measurement result of the contact resistance on the sliding contact surface.

* Explanation of symbols for main parts of the drawings

1: fixed contact 2,8: high conductor

3: fixed contact 6: movable contact

4: movable contact 5: movable conductor

7: holder 9,10: L-shaped conductor

11: S-shaped conductor 12: support shaft

13 compression spring 14 contact spring

15: sliding contact

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to sliding contacts for connecting electrical conductors in various electrical devices such as circuit breakers, and more particularly to surface treatment of these sliding contacts.

In electrical equipment having a mechanically moving conductive portion, such as a circuit breaker, a disconnect catcher, a load breaker or a connector, the sliding contact is used between the movable portion and the fixed portion.

Since the sliding contactor changes instantaneously during the sliding movement, the contact resistance during the sliding movement tends to be unstable and high compared with the stationary state. When the contact resistance is increased, the contact portion is heated by the electric energy. Here, when the contact surface is copper or a copper alloy, the contact resistance is further increased by oxidation, thereby further promoting oxidation. In order to prevent such a vicious cycle, conventionally, silver (Ag) plating is performed on the contact surface of the sliding contact through which a large electric current flows.

However, Ag plating is soft, so that damage is easily caused, and even at no load opening and closing, the wear of the base portion covered with silver plating is exposed. At the time of energization, the soft nitriding of Ag is also promoted by electric heat, and the plating layer is peeled off by sliding, and when the current becomes large, the contact portion generates heat by melting. This heat generation is suppressed to some extent as the contact force of the sliding contact increases, but as the contact force increases, the mobility of the sliding contact deteriorates accordingly, thereby increasing the size of the driving mechanism and the spring for increasing the contact force. In addition, as the contact force is increased, the frictional force is increased, which causes another damage of the plating layer, which is damaged by the current load.

In order to cope with such a phenomenon, the operation | work which has apply | coated electroconductive grease to Ag plating film is also performed. This method has the effect of preventing damage to the coating film, and also has the effect of stabilizing low contact resistance in the stationary state, but according to the experiments of the present inventors, the contact resistance is high in the non-slip sliding process, and a large current flows. In this case, larger fusion occurred than when no grease was applied. In addition, grease tends to solidify when used at high temperatures for a long time, so its use is limited.

Accordingly, an object of the present invention is to provide a sliding contact that can be energized with a low sliding contact resistance even in a sliding movement process.

The sliding contact of the electrical device of the present invention for achieving this purpose has a composite coated surface of graphite (C) particles dispersed in an Ag matrix, the sliding contact with the mating conductor, the concentration of 2-100g / ℓ The metal in the range is for dispersing potassium cyanide in a concentration of 2-250 g / l, potassium hydroxide in a concentration of 0.5-15 g / l, graphite powder in a concentration of 1-550 g / l, and graphite powder in a plating solution. The coating surface is formed by electroplating using a plating solution containing a dispersant in the range of 2000 ppm.

Other objects and advantages of the present invention can be more readily understood and can also be readily implemented through the means set forth in the following detailed description claims.

Next, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1A and 1B show a sliding contact of a power circuit breaker comprising a fixed conductor and a movable conductor in sliding contact with the fixed conductor as an embodiment of the present invention. In the figure, 1 is a fixing consisting of a fixed conductor 2 of copper material fixed to a case of a circuit breaker (not shown) by screws or other suitable means (not shown) and a contact point 3 attached to the tip thereof. The contactor 4 is a movable contactor consisting of a movable conductor 5 of copper material and a contact 6 attached to the tip thereof, which is driven by an opening / closing mechanism (not shown) and pivots for opening and closing, and 7 is a movable contactor ( Holder 4 of the insulator holding 4) is a high conductor connected to a heating element of an overcurrent trip device (not shown).

Each high conductor 8 is an upright L-shaped conductor 9 fixed to a case with a screw (not shown), an L-shaped conductor 10 horizontally bonded thereto, and an S-shaped horizontally bonded thereto. The L-shaped conductor 10 and the S-shaped conductor 11 are made of a conductor 11, and together with the movable conductor 5 as shown in the figure, while sandwiching the movable conductor 5 as shown in FIG. Done.

A support shaft 12 for rotating the movable conductor 5 is inserted between the movable conductor 5 and the conductors 10, 11, and both ends of the support shaft 12 are held by the holder 7. It is. Compression springs 13 are respectively inserted between the two conductors 10 and 11 and the holder 7 to bring the conductors 10 and 11 into pressure contact with the movable conductor 5. Reference numeral 14 denotes a contact spring inserted between the means and the case of each movable conductor 5 to pressurize the movable conductor 5 in the counterclockwise direction of the drawing, and to contact the contact pressure between the fixed contact 3 and the movable contact 6. Generate.

In this state, the current flowing from the stationary contactor 1 to the movable contactor 4 includes the sliding contact 15, the L-shaped conductor 10, and the S-shaped conductor 11, which are indicated by an oval dotted line in FIG. 1A. It flows to the high conductor 8 via it, and reaches the load side terminal board again via an overcurrent trip device (not shown). When the operation handle (not shown) in the closed state is operated in the open state or the overcurrent trip device trips, an opening / closing mechanism (not shown) is operated to move the movable contactor 4 rapidly. 12) is a turning point in the clockwise direction of Fig. 1B. At this time, the movable conductor 5, the L-shaped conductor 10, and the S-shaped conductor 11 slide in each sliding contact portion 15.

According to the present invention, at least one sliding contact surface in each sliding contact portion is coated with a composite in which C is dispersed in the Ag matrix. As is well known, carbon C has excellent lubricity and good conductivity and does not fuse with Ag at all. Therefore, by coating the sliding surface with a finely dispersed film of C powder in the Ag matrix, the occurrence of damage is eliminated, and the contact resistance is kept low during the sliding process. Further, even when a large current flows, even when the contact portion melts due to heat generation, the contact portion is not fusion-bonded, and the sliding contact surface remains flat and smooth, so that stable energization can be continuously performed.

According to the present invention, by forming a coating surface of a composite material in which C is dispersed in the Ag matrix on the sliding contact surface, the contact resistance in the sliding movement process is kept low, and heat generation by the energizing current is suppressed, and the mechanical sliding movement wear is also reduced. As a result, the sliding contactor having a high current carrying capacity and a long service life can be formed. In addition, since the heat generation is small, the contact force can be reduced, and as a result, a spring mechanism for imparting the contact force or a drive mechanism for moving the contactor can be configured with a small capacity, thereby miniaturizing the whole apparatus.

The following examples, which represent composites, will facilitate an understanding of the present invention.

Example 1

In the sliding contact portion 15 of the illustrated circuit breaker, in the embodiment, Ag-6% having 6% (vol%) of C dispersed in the Ag matrix on the movable conductor 5 and the high conductor 8, respectively, in the following manner. The film of C composite was coated by electroplating to a thickness of 7 탆 to form a coated surface.

FIG. 2 is an electron micrograph (900 times magnification) showing a dispersion state of C in the plating coating surface obtainable by Example 1, in which black spots in the drawing represent C. FIG.

The reason for stirring in the following "B plating conditions" is to make the graphite powder mixed in the plating liquid uniformly distributed throughout.

As the plating process proceeds, the graphite powder in the plating liquid is gradually consumed, thereby decreasing the concentration of the graphite powder. In order to precisely control the content of C in the coating film of silver plating, it is necessary to constantly maintain the concentration of the graphite powder in the plating solution, so that when the concentration decreases, the graphite powder is immediately replenished and replenished. Since the distribution of the graphite powder supplied immediately after the diffusion of the graphite powder is biased in the plating liquid, the plating liquid is agitated for uniform distribution.

A. Composition of Plating Solution

Metallic silver concentration: 35g / ℓ

Potassium Cyanide: 110g / ℓ

Potassium Hydroxide: 8g / ℓ

Graphite powder: 20g / ℓ (C particle size: Long diameter 0.5-2μm, Short diameter 0.2-0.5μm)

Dispersant of Graphite Powder in Plating Solution: 200ppm

B. Plating Condition

Anode: Silver Plate

Plating solution temperature: 20 ℃

Current density: 1 A / dm ²

Agitation: Yes

Example 2

In the same manner as in Example 1, the movable conductor 5 and the high conductor 8 were each formed by electroplating a coating surface of Ag-3% C (vol%) with a thickness of 7 μm. The plating conditions at this time were the plating liquid temperature of 35 degreeC, C-5 particle | grain long diameter of 0.8-5 micrometers, and short diameter of 0.3-1 micrometer, except the same as that of Example 1.

Comparative Example

In addition, as a comparative example, 7 μm Ag plating was prepared with a movable conductor 5 and a high conductor 8 (comparative example 1) having the same shape, and a grease applied thereto (comparative example 2).

[Comparison Experiment Result]

The movable conductor 5 and the high conductor 8 were assembled in a circuit breaker, and the no-load switching test and the large current interruption test were carried out. In addition, in the no-load switching test, the sliding contact unit 15 repeats the reciprocating sliding movement in the non-energized state, and in the large current breaking test, the sliding contact unit 15 is slid in the energized state, and the experimental results are shown in Table 1.

As shown in Table 1, the sliding contact plated with the Ag-C composite material of the present invention did not expose the base material under the plated coating surface. However, it can be seen that the application of grease is particularly damaged under the condition of having the same strength or less as shown in Table 1.

TABLE 1

3 shows the results of measuring the contact resistance of the sliding contact portion 15 by sliding the DC10A in the sliding contact contacts of Examples 1, Comparative Example 1 and Comparative Example 2 while flowing. The contact resistance in the stationary state is small between the three characters, but during the sliding movement, the contact resistance of the sliding contact plated with Ag-6% C (volume%) is the lowest and the variation is small. In general, the temperature of the electrical contact of the contactor is proportional to the voltage of the contact, that is, the value of current x contact resistance, so the temperature during energization during sliding movement is minimal when plated with Ag-6% C (volume%) composite.

In the above embodiment, two examples of the sliding contact of the circuit breaker are shown, but the effect of the present invention depends on the properties of C, but the volume percentage of C or the size of C particles is not limited thereto. Since the degree of damage or melting of the sliding contact is also affected by the area of contact or the surface pressure, the volume percentage of C or the size of C can be determined collectively by considering all of these factors. However, conductive C has electric resistance of several hundred to several thousand times Ag. Therefore, it is not preferable to pass the plating thickness by using large C particles in a state where the volume percentage of C is unnecessarily increased, since the heat generation of the sliding contact portion is increased.

In addition, in the above embodiment, the case of the electroplating coating is shown, but the important point here is the fact that the coating is a composite of Ag and C, the coating film forming method is not limited to electroplating.

Contributing to the prevention of damage or welding is the presence of C on the sliding contact surface, so forming only Ag-C coating on either of the movable conductor and the fixed conductor is effective. In that case, it is preferable to perform Ag plating on other parts, but since C has an anti-oxidation effect, it is possible to obtain electrical current having only copper itself. In addition, it is not necessary to coat the coating film on the front surface of the conductor, and it is preferable to form only the sliding contact surface.

In addition, fine particles having a hard nature as the third particles to Ag-C, for example, SiC, WC, ZrB, Al ₂ O ₃ , ZrO ₂ , Cr ₂ O ₃ , TiO ₂ , R ₂ O ₃ , ThO ₂ , Dispersing the particles of Y ₂ O ₃ , MoO ₃ , W ₂ C, TiC, B ₄ C, CrB _2, etc. increases the hardness of the entire coating film, and can form a contact portion with a longer life in wear.

In addition, as the plating condition, a basic powder was used in the plating solution composition in the range of 2-100 g / l of metal silver, 2-250 g / l of potassium cyanide, and 0.5-15 g / l of potassium hydroxide. It can be used even in the range of -550g / l. Graphite diameters of 0.05-25 μm may be used, but 0.2-10 μm is more preferred.

Although various embodiments have been described above, the scope of the present invention is not limited thereto, and various changes and modifications may be made by those skilled in the art without departing from the spirit and scope of the following claims. This is possible.

Claims (2)

In the sliding contact of an electrical device having a coating surface coated with a composite material in which graphite (C) particles are dispersed in an Ag matrix, and in sliding contact with a counter conductor, a metal having a concentration in the range of 2 to 100 g / l is a concentration of 2 Plating solution containing potassium cyanide in the range of 250 g / l, potassium hydroxide in the range of 0.5-15 g / l, graphite powder in the range of 1-550 g / l, graphite powder and dispersant in the concentration range of 10-2000 ppm The sliding contact of the electric machine, characterized in that for forming the coating surface by electroplating. According to claim 1, SiC, WC, ZrB, Al ₂ O ₃ , ZrO ₂ , Cr ₂ O ₃ , TiO ₂ , R ₂ O ₃ , ThO ₂ , Y ₂ O ₃ , MoO ₃ , W ₂ C, TiC, A sliding contact of an electric machine, wherein fine particles having a hard property selected from the group consisting of B ₄ C, CrB ₂ , and the like are dispersed in an Ag-C composite material as third particles.