DD271194A1 - PROCESS FOR REFORMATING ELECTROLYTE CAPACITORS - Google Patents

Abstract

The invention relates to a method for reformulating bipolar electrolytic capacitors after the manufacturing process. It is an object of the invention to minimize by a suitable Nachformierverfahren the damage of the oxide layer by incorrect polarity, to obtain two uniformly well-formed anode foils. This is achieved by subjecting pre-assembled capacitors whose coils have not yet been reformed to 50 Hz alternating current treatment. Due to the high power dissipation is selected very short in duty cycle and so long pauses between the power-up phases that the capacitor is not heated up and destroyed by the power loss inadmissible.

Description

Field of application of the invention

The invention relates to a method for reforming bipolar electrolytic capacitors after the manufacturing process, before they are subjected to the final test.

Characteristic nos known prior art For the production of electrolytic capacitors are coated with a dielectric oxide layer coated aluminum foils

used, called anode foils for short. The aluminum oxide layer is formed by the so-called preforming process in

Continuous process applied to the aluminum foils. The quality of this he oxide layer (dielectric) determines the quality

of the capacitor. During the subsequent production process, the foamed anode foils land on the

cut corresponding bandwidths, resulting in cut edges that have no oxide layer. By rewinding and producing the capacitor winding, the very sensitive, brittle and only max. 0.7 mm thick oxide layer damaged.

For these reasons, it is imperative after the impregnation of the coil or after completion Jes capacitor

To subject this to a reforming to heal all defects of the oxide layer and the cut edges

form.

This process is only correct if the anode foil has a positive polarity, since the oxide layer is only polarized in this polarity Compound with the electrolyte acts as a barrier and new oxide can form. In case of wrong polarity is the oxide layer

practically conductive and is reduced in continuous wrong polarity with higher voltage in their quality.

In polar electrolytic capacitors no problems arise in this regard, since in these a polarity reversal is not required For bipolar electrolytic capacitors, both anode foils must be reformed. In the assembled capacitor is

a temporary polarity reversal of the two anodes inevitably necessary.

In a known manner, it is possible to first correct the one and then the other anode foil, and in each case the

total necessary time of z. For example 6 hours each. This process has the disadvantage that the last incorrectly poled anode loses very much its quality, the residual current has increased considerably, an already improved cycle, in which the two anodes are reformed, and each foil, for example, is improved 3 times 2 hours is on voltage and thus the

Polarity is shorter. It is even better if the cycle times are shorter towards the end of the formation,

z. B. per anode 3.2 and 1 hour in alternation, so that the total time of 6 hours is maintained. But even with the wrongly poled anode damage remains, despite the long forming time of 2 times 6 hours.

Object of the invention

The aim of the invention is to minimize by a suitable Nachformten / experienced for bipolar capacitors, the damage of the oxide layer by false polarity to obtain two uniformly well-formed anode foils.

Explanation of the essence of the invention

The invention is based on the object, a bipolar electrolytic capacitor in the already assembled state, in which the access to a possibly lying between the two anode sheets neutral unformed film is not possible to reformate so that by the case inevitable false polarity of an anode whose oxide layer not harmed. Bipolar electrolytic capacitors, e.g. Motor starting capacitors are operated in the application with relatively high AC voltage in the range between 100 and 380V.

As a result of the large loss factor of electrolytic capacitors, up to 10% of the AC power goes into heat

implemented. For this reason, starting electrolytic capacitors are only allowed for duty cycle up to 3s bji a nominal playing time of 3 min. The duty cycle is between 0.55 and 1.7%. Based on this mode of operation, the proven

No damage to the oxide layers results, the problem of reforming was solved as follows. Ready assembled capacitors that have not yet been reformed as a coil undergo AC treatment

of 50Hz for the purpose of reforming. Due to the high power dissipation, the duty cycle is chosen to be very short and pauses between the power-up phases so long that the Kondensatorsich not permitted by the power dissipation heats up and is destroyed. However, a certain degree of self-heating has a positive effect on the process.

If you want to avoid the strong self-heating, so you choose an AC of lower frequency. It has been shown that with this method, the Nachformierspannungen can be chosen smaller, z. B. only the Nominal AC voltage instead of 1.4 times the same. Another advantage of this method is the recognition that the total Nachformierzeit including pause time at AC forming can be reduced from 12 to 1-2 hours, with the quality of the capacitors being better than

after the old procedure. By shortening the total time it becomes possible for the first time, the capacitors in the

Automatically re-formulate throughfeed processes. embodiment The inventive method will be explained in more detail by an embodiment. Ready mounted bipolar capacitors with a capacity of 100pF and a nominal AC voltage of 320 V are included

following parameters: *

Reforming voltage: 320 V AC 50 Hz Duty cycle: 3 s Break time: 3 min Total time: 2 h

For the purpose of gentle treatment, the voltage at the beginning of the formation on z. B. 80% reduced and only after half of the Gesamtformierzeit be regulated to the specified height.

The process according to the invention leads to capacitors whose anode foils are uniformly reformed and result in extremely low residual currents. The other properties such. B. heat balance are positively influenced in this way.

Claims (5)

1. A method for reforming of electrolytic capacitors, such as motor starter capacitors, at
where both anodes are formed one after the other, one of which is always exposed to a wrong polarity, characterized in that the reforming with alternating voltage in the
Intermittent operation is performed. 2. The method according to claim 1, characterized in that the height of the AC voltage
is between 50 and 140% of the nominal AC voltage of the capacitor and the frequency in
Range is selected from 1 to 120 Hz, preferably the respectively available
Mains frequency. 3. The method according to claim 1 and 2, characterized in that the formation with
AC voltage in intermittent operation takes place, in particular with 0.2 to 3% relative duty cycle. 4. The method according to claim 1 to 3, characterized in that the Gesamtformierdauer 0.25 to 6 hours, in particular 2 hours. 5. The method according to claim 1 to 4, characterized in that to comply with the changing
Forming conditions of the overall process is carried out automatically.