JPS5819074B2 - How to test a capacitor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for testing polar capacitors such as electrolytic capacitors.

Normally, this type of capacitor is inspected in the order of measurement of short circuit, leakage current, and Ctan δ while being transported on a belt conveyor or the like.

Before each inspection step, there is usually a step of charging the capacitor to the voltage value required for that inspection.

By the way, when measuring leakage current, it is necessary to charge the capacitor with a high voltage, but in the next Ctan δ measurement step, a charging voltage as low as 1.5 V is sufficient, so the capacitor after leakage current measurement can be used as is. It cannot be sent to the next process, and a process is required to discharge the charged high voltage.

For this reason, an increase in the number of processes is unavoidable, but in addition to this disadvantage, there is a problem in terms of work efficiency because it takes a long time to discharge because it is charged to a high voltage. It also has some drawbacks.

In other words, if you short the terminals of a capacitor charged to a high voltage, it can be discharged in a short time, but this will generate a surge current and damage the capacitor, so connect a high resistance and gradually discharge the capacitor. In other words, it is necessary to discharge the battery over time.

Normally, the time required for this discharge is about 10 seconds.

Moreover, after completing this discharge, it is necessary to charge the Ctan δ to the charging voltage required for measurement, and taking this charging time into consideration, one cage current must be measured and then Ctan δ
It takes a considerable amount of time to measure.

In this regard, the present invention focuses on the fact that the charging voltage required for the next measurement step is lower than the charging voltage required for measuring the leakage current, and improves the discharging process after measuring the leakage current. This method attempts to obtain the charging pressure required for the measurement in the next process all at once during the process, thereby solving the drawbacks and disadvantages of the conventional capacitor testing methods.

The capacitor inspection method of the present invention will be explained below. Figure 1 is a process diagram showing various inspections of capacitors.
In the charging step 1, the battery is charged to a required voltage and sent to the short-circuit inspection step 2, where it is inspected for the presence or absence of a short circuit.

If this test result determines that the product is good, it is recharged to the required voltage in the second charging process 3 and leakage current measurement process 4.
The leakage current is measured.

Next, the capacitors determined to be good in the measuring step 4 are sent to the discharging step 5, where their charge voltage is discharged, but since a clamp circuit, which will be described later, is used in this step 5, the capacitors are completely The battery is not discharged and is clamped to a voltage of, for example, 1.5μ, which is necessary for charging in the next step 6.

Then, the capacitor clamped to the required charging pressure in step 5 is sent to the next Ctaro δ measurement step, and the Cta port δ is
The entire inspection process is completed with the measurement of .

FIG. 2 shows the clamp circuit used in the discharge step 5, and Cx is the capacitor to be measured after leakage current measurement, and is charged to a high voltage as described above.

R is a discharge resistor, and discharge starts through this discharge resistor R at the same time as the capacitor to be measured Cx is connected.

As is well known, the time constant of this discharge is CxR.

E is a bias power supply for measurement in the next step 6, and the power supply E and diode D serve to clamp the capacitor Cx to be measured to a required voltage.

That is, when the capacitor Cx whose leakage current has been measured is connected as shown in FIG. 2, the charged high voltage is first discharged through the discharge resistor R, but the voltage between the terminals of the capacitor Cx is biased. When the voltage drops to be equal to the voltage of the power source E, it is charged by the bias power source E via the diode D, so the voltage does not drop below that level and is clamped to the bias voltage.

As described above, in the capacitor inspection method according to the present invention, in the discharging process after measuring the leakage current of the capacitor to be measured, the capacitor is connected in the forward direction with a diode and a series circuit with a constant voltage bias power supply. Since the terminal voltage of the measurement capacitor is clamped to a voltage equal to the bias power supply required for the next measurement process, it only requires a single process, the discharge process, which reduces the number of processes and completely eliminates the need for conventional methods. Compared to the method of discharging and then charging, this method can significantly shorten the time and can be expected to improve work efficiency.

Note that when measuring C, tan δ, an AC voltage is applied to the capacitor under test, but if the DC bias method of the method of the present invention is not applied, a leakage current will flow during the measurement of Cta port δ, and tan δ will appear. However, when the method of the present invention is applied, Its Cta
If the charging voltage is clamped at the required charging pressure in the discharging process before the nδ measurement process, the above-mentioned drawbacks can be overcome without increasing the number of processes.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the capacitor testing method according to the present invention, and FIG. 2 is an electric circuit diagram showing an example of the main operations of the method of the present invention.

Claims (1)

[Claims] 1. In the discharging process after measuring the cage current of a polar capacitor to be measured, by connecting a diode and a series circuit with a constant voltage bias power supply to the same capacitor in the forward direction, the terminal voltage of the capacitor to be measured can be adjusted to the next step. A capacitor inspection method characterized by clamping to a voltage equal to the bias power supply required for measurement.