A method of manufacturing a dual coil plastic film capacitor

Abstract

The present invention relates to design and manufacturing process of plastic film capacitors for energy conservation in air conditioners. More particularly it relates to a design of plastic film capacitors by connecting two capacitor coils in parallel combination there by improving current handling capacity and reducing current consumption and losses during its use in air conditioner across compressor where running current is high and ultimately conserving energy, and also to increase life expectancy.

Description

Field of invention: The present invention relates to a plastic film capacitor. More particularly it relates to dual coiled plastic film capacitor. Further, more specifically it relates to a dual coil plastic film capacitor where the coils are connected in parallel to improve current handling capacity and reduce power consumption during its use in air conditioners and refrigerators. Also it relates to method of manufacturing such a dual coil plastic film capacitor. Prior art: Currently in the field of air conditioning and refrigeration, a single coil plastic film capacitor is used. This capacitor is connected across the compressor of the air conditioner or refrigerator where running current is high. Some time only one single coil plastic film capacitor is sufficient but many times more than a single coil in plastic film capacitor is required. In such a situation these several single coil capacitors are connected in series and parallel as per the need. Such arrangement of single coiled capacitors in air conditioners and refrigerators suffers from the following problems: 1. Poor contacts among the plurality of single coiled capacitors 2. More space requirement 3. Poor current handling capacity 4. Low pulse rise time i.e low dv / dt value 5. High power consumption 6. Heat generation during operational use 7. Life of the capacitors get reduced Due to all the above mentioned problems the dielectric strength of the capacitor get reduced and ultimately leads to failure of capacitor. Hence there is need to overcome the above drawbacks of the prior art capacitor. Objective of the invention: The object of the present invention is to provide improved plastic film capacitors, which eliminates the above said drawbacks associated with the prior art plastic film capacitor. Another object of the present invention is to provide an improved plastic film capacitor with improved current handling capacity. Another object of the present invention is to reduce power consumption during use of such plastic film capacitor. Yet another object of the present invention is to improve pulse rise time (i.e dv / dt value) of a plastic film capacitor. Still another object of the invention is to eliminate heat generation during the operational use of a plastic film capacitor. Yet another object of the present invention is to provide an improved plastic film capacitor with long life. Statement of the invention: The aforesaid objects are achieved if instead of using single coil plastic film capacitor of a specific capacitance value someone uses the dual coil plastic film capacitor of the same value in which two capacitor coils having capacitance value equal to half the capacitance value of the double coil plastic film capacitor are connected in parallel. Accordingly there is provided a method of manufacturing a dual coil plastic film capacitor comprising: 1. Preparing separately two capacitor coils having the same value of capacitance, wherein preparation of each capacitor coil includes: a placing in vacuum a plastic dielectric film and depositing a thin layer of metal alloy as electrodes on it; b. winding a metallised film into a cylinder so that a metallised edge extends on each end of the wound capacitor section; c. spraying both ends with small droplets of molten metal that adhere alone & make contact with the metallisation on the film; d. soldering the braided wire lead to this end sprayed metallised portion for making termination contact, 2. Connecting said capacitor coils in parallel to get single capacitor having capacitance value equal to sum of the capacitance value of said two capacitor coils; 3. Preheating said single capacitor obtained in step (2) by keeping it in air ventilated oven at temperature between 70° to 107°C for period of 10-15 minutes; 4. Impregnating said preheated capacitor coil into amine based epoxy under vacuum for period of 10-15 minutes; wherein said amine base epoxy contains amine base resin and hardener in the ratio of 100:72.5 and which having property of getting solid at temperature of between 70°-150°C and said epoxy is kept under vacuum before impregnation to remove excess air inside said epoxy. 5. Drying said impregnated capacitor by keeping it in air ventilated oven at a temperature between 70°tol07°C;and 6. Encapsulating and sealing dried impregnated capacitor. According to one embodiment of the invention both capacitor coils are connected in parallel by soldering the terminals of the said capacitor coils According to one embodiment of the invention the capacitor coil is preheated at temperature of 85°C. According to another embodiment of the invention preheating of capacitor coil is done for period of 12 minutes. According to another embodiment of the invention impregnation is carried out for a period of 10 minutes. Brief description of the drawings: Fig 1: Shows the single coil plastic film capacitor available in prior art. Fig 2: Shows symbolic representation of the single coil plastic film capacitor available in prior art Fig 3: Shows the dual coil plastic film capacitor according to the present invention in which two single coils are connected in parallel. Fig 4: Shows the symbolic representation of the dual coil plastic film capacitor according to the Present invention. Detailed description of the invention: The above, and other objects, features and advantages of the invention will become apparent from the following description read in conjunction with the accompanying drawings. Meaning of the reference numerals used in the drawings is as follows: In figures 1 and 2: 1 : Single coil plastic film capacitor 2 : Wound coil capacitor 3 : Lead wires for terminal contact 4 : Encapsulation and sealing 5 : Dielectric film 6: Electrodes In figures 3 and 4: 11: Dual coiled plastic film capacitor 12 : First capacitor coil 13 : Second capacitor coil 14: Dielectric film 15 : Electrodes 16 : Lead wires for terminal contact 17: Welded / soldered contact points 18 : Encapsulation and sealing Tl : First terminal contact of the first capacitor coil T2 : Second terminal contact of the first capacitor coil T3 : First terminal contact of the second capacitor coil T4 : Second terminal contact of the first capacitor coil The method of manufacturing dual coil plastic film capacitor according to the present invention consists of parallel connection among two single capacitor coils having the same capacitance value. Both of these capacitor coils are prepared first separately manufactured. For manufacturing each of the capacitor coil first a plastic dielectric is placed in a vacuum and a thin layer of metal alloy as an electrodes is deposited on it Then a metallised film is wound into a cylinder so that a metallised edge extends on each end of the capacitor winding. Both ends are then sprayed with small droplets of molten solder mat adhere along and make contact with the metallisation on the film and finally the braided wire lead is soldered to this end sprayed metallised portion for making termination contact In this way both capacitor coils arc prepared separately by above mentioned method. After these both of capacitor coils are connected in parallel. Due to the parallel combination we get the single capacitor having capacitance value equal to the sum of the capacitance value of two capacitor coils. The parallel combination is done by soldering the terminals of the capacitor coils in parallel. Thereafter this composite capacitor which is obtained by the parallel connection of two capacitor coils is preheated by keeping it in air ventilated oven at temperature between 70°C to 107°C for period of 10 to 15 minutes. Then the preheated capacitor is impregnated by an amine base epoxy under vacuum for a period of 10 to IS minutes. The amine base epoxy contains mine base resin and hardener in the ratio of 100:72.5 and having property of getting solid at a temperature between 70° to 150°C. This epoxy is kept under vacuum before impregnation to remove excess air inside said epoxy. Then the impregnated capacitor is dried by keeping it in an air ventilated oven at a temperature between 70° and 107°C and finally the capacitor is encapsulated and sealed. Now referring to figure 1, it shows the single coil plastic film capacitor (1) of the prior art It consists of single capacitor coil (2) which is encapsulated and sealed (4). Such a capacitor (1) is generally connected across the compressor of an air conditioner or refrigerator for the initial start of the system. Many times series or parallel combination of such single coiled capacitors is used as per the need But due to single coiled construction, capacitor consumes more power. Also the current handling capacity becomes very poor. Further heat generation is excessive. This leads to weakening of the dielectric strength of the capacitor and finally capacitor meets the failure. All these problems are resolved by the invented dual coil plastic film capacitor. According to the present invention, instead of using single coil, parallel combination of two coils is used. Suppose if in the prior art a single coil capacitor having capacitance value "C" was used, then according to present invention instead of using single coil capacitor having capacitance value "C", parallel combination of two capacitor coils each having capacitance value "C / 2" is used. Due to parallel combination of two capacitor coils having capacitance value "C / 2", finally we get the capacitor with capacitance value equal to "C". Now referring to figure 3, a dual coil plastic film capacitor (11) is shown. In this capacitor two capacitor coils (12, 13) having same capacitance value are connected in parallel. As shown in figure 3, two capacitor coils (12, 13) having same capacitance value are connected in parallel to obtain a single composite capacitor (11) having capacitance equal to the sum of the capacitance values of the two capacitor coils (12,13). Both coils (12,13) are connected in parallel by soldering their terminal contacts (Tl, T2, T3, T4) in parallel. Terminal contacts (Tl, T2, T3, T4) are made from braided lead wire (16). After that whole assembly is encapsulated and sealed (18). In figures dielectric film (14) and metallic electrodes (15) are also shown. Example: The following example will illustrate how the dual coil plastic film capacitor of die present invention is manufactured and how it is superior man the prior art plastic film capacitor. The example given hereafter is only as an illustration, it does not by any means limits the invention. First we will see how the dual coil capacitor having capacitance value of 45 uf is manufactured by the method of the present invention. First of all two capacitor coils having capacitance value 22.5 uf are prepared separately. Materials and processes given below for manufacturing two coils each with capacitance value 22.5μf arc detailed below : For preparing each capacitor coil having capacitance value 22.5uf, a plastic dielectric film is placed in a vacuum and a thin layer of metal alloy as an electrodes is deposited on it Then a metallised film is wound into a cylinder so that a metallised edge extends on each end of the wound capacitor section. Both ends are then sprayed with small droplets of molten metal that adhere along and make contact with the metallisation on the film and finally the braided wire lead is soldered to this end sprayed metallised portion for making termination contact In this way both capacitor coils having capacitance value 22.5uf are prepared separately by above mentioned method. After this both of the capacitor coils having capacitance value 22.5 uf are connected in parallel. Due to parallel combination we get the single capacitor having capacitance value equal to sum of capacitance value of two capacitor coils i.e 45uf (2.5uf + 22.5uf = 45jif). The parallel combination is done by soldering the terminals of the capacitor coils in parallel. Thereafter single capacitor which is obtained by the parallel connection is preheated by keeping it in air ventilated oven at temperature between 70° to 107°C for period of 10 to 15 minutes. The amine base epoxy contains amine base resin and hardener in the ratio of 100:72.5 and which having property of getting solid at temperature of between 75° to 150° C and this epoxy is kept under vacuum before impregnation to remove excess air inside said epoxy. Then the impregnated capacitor is dried by keeping it in air ventilated oven at a temperature between 70° to 107°C and finally capacitor is encapsulated and sealed Thus we obtain the dual coiled capacitor with capacitance value 45 μf Now we will compare the properties of this dual coiled plastic film capacitor having capacitance value 45 uf With the single coiled plastic film capacitor having capacitance value 45 μf of the prior art For this the single coiled plastic film capacitor having capacitance value of 45 μf of the prior art is installed across the compressor of the air conditioning system. It is observed that during use this capacitor consumes 13.5 Amp continuously. At the same time heat generation during the operational of this capacitor, is also observed. Then the dual coil capacitor having capacitance value 45 μf of the present invention is taken and installed across the compressor of the air conditioning system. It is observed that during use this capacitor , it consumes 11.5 Amp only. At the same time heat generated during use of this capacitor is much less. From this example it is clear that dual coil plastic film capacitor of the present invention consumes less power as compared to the prior art single coiled plastic film capacitor. Also heat generation during the operational use of the dual coiled capacitor is less as compared to the prior art single coiled capacitor. Industrial Applicability: The dual coil plastic film capacitor of the present invention is basically related to electronics and electrical industries. It is generally used in air conditioners and refrigerators. The present invention is not limited to the above described embodiments , and various alterations, modifications, and / or alternative applications of the invention may be possible, if desired, without departing from the scope and spirit of the invention which can be read from the claims and the entire specification. All these possible alterations, modifications and / or alternative applications of the invention are also intended to be within technical scope of the present invention.

Claims

We claim:

1. A method of manufacturing a dual coil plastic film capacitor comprising: i. Preparing separately two capacitor coils having same value of capacitance, wherein preparation of each of said capacitor coils includes: a. placing in a vacuum a plastic dielectric film and depositing a thin layer of metal alloy as an electrodes on it; b. winding a metallised film into a cylinder so mat metallised edge extends on each end of the wound capacitor section; c. spraying both ends with small droplets of molten metal that adhere along & make contact with the metallization on the film; & soldering the braided wire lead to this end sprayed metallised portion for making termination contact; ii. Connecting said capacitor coils in parallel to get single capacitor having capacitance value equal to sum of the capacitance of said two capacitor coils; iii. Preheating the capacitor coil obtained in step (ii) by keeping it in air ventilated oven at temperature 70° to 150°C for period of 10-15 minutes; iv. Impregnating said preheated capacitor coils into amine base epoxy under vacuum for a period 10 to IS minutes; wherein said amine base epoxy contains amine base resin and hardener in the ratio of 100:72.5 and which having property of getting solid at temperature of between 70° to 150°C and said epoxy is kept under vacuum before impregnation to remove excess air inside said epoxy; v. Drying said impregnated capacitor coil by keeping it in air ventilated oven at a temperature up to 70° to 107°C; and vi. Encapsulating and sealing dried impregnated capacitor coil.

2. A method of manufacturing dual coil plastic film capacitors as claimed in claim 1 wherein both capacitor coils are connected in parallel by soldering the terminals of said capacitor coils in parallel.

3. A method of manufacturing a dual coil plastic film capacitor as claimed in claim 1 wherein capacitor coil is preheated at 85°C.

4. A method of manufacturing a dual coil plastic film capacitor as claimed in claim 1 wherein capacitor coil is preheating of capacitor coil is done for a period of 12 minutes.

5. A method of manufacturing a dual coil plastic film capacitor as claimed in claim 1 wherein capacitor coil is preheating of capacitor coil is done for a period of 10 minutes.

6. A dual coiled plastic film capacitor manufactured by the method as claimed in claims 1 to 5.

7. A method of manufacturing a dual coil plastic film capacitor as herein before described and illustrated with reference to accompanying drawings.

8. A dual coil plastic film capacitor as herein described and illustrated with reference to accompanying drawings.