Analysis on the selection and inspection method of compressor capacitor

Compressor capacitors are essential in many home appliances. For example, air conditioners also have compressor capacitors, but they must be mastered and understood in terms of selection and inspection. After all, for compressor capacitors, its quality affects the normal operation of the equipment. Therefore, we must pay attention to understanding and mastering relevant knowledge.

For the compressor capacitor inspection, it is first necessary to check from the appearance. Compressor capacitors are divided into dry type and oil-immersed type. Dry-type capacitors are mostly packaged in plastic shells, while oil-immersed capacitors are packaged in metal shells. Therefore, if the shell is found to be deformed, convex, cracked, or leaking, it means that the capacitor It has been damaged and can no longer be used; the replacement capacitor should be the original specification model as far as possible, and cannot be replaced at will.

The second is to check the capacity of the capacitor. Relatively speaking, the capacity of the capacitor will attenuate due to the harsh environment and the extension of time. Generally, if the attenuation is greater than 20%, there will be difficulties in starting, large starting current, and long starting time; especially when the power supply voltage is lower than 20 %, there will be a start trip, over-current protection, and even burn out the compressor. Therefore, when there are phenomena such as difficulty in starting, long start-up time, and instantaneous stop, the capacitor should be checked first.

Measurement methods:

1、Roughly measure the charge and discharge time with the resistance gear of the pointer multimeter: the red and black test leads respectively touch the two poles of the capacitor, the needle rises rapidly and then falls back to the original position slowly and quickly, which is a good capacitor.If the needle does not rise or does not return to its original position after rising, it means that the capacitor is broken;

2、Use a digital multimeter capacitance file or a special capacitor to measure and measure; the choice of compressor capacitor needs to be selected from its appearance and capacity, and at the same time it is necessary to master and understand its inspection method, which can effectively help people understand and check whether it appears question.Only in this way can it be ensured whether there is a problem with the compressor capacitor and the failure to operate normally.

High-voltage chip capacitors, also known as ceramic multilayer chip capacitors, are a production technology using ceramic powder. The interior is made of precious metal palladium and gold, and silver is plated on ceramics as electrodes by high-temperature sintering.The products are divided into two materials: high-frequency porcelain NPO (COG) and low-frequency porcelain X7R. NPO has a small package volume, a capacitor with a high temperature resistance coefficient, and good high-frequency performance. It is used in a high-stable oscillation circuit as a circuit filter capacitor.X7R ceramic capacitors are limited to be used as bypass or DC blocking in circuits with common operating frequencies, or in occasions that do not require high stability and loss. Such capacitors are not suitable for use in alternating current (AC) pulse circuits, because they are easy to be damaged. Pulse voltage breakdown, so it is not recommended to use in AC circuits.

There are three types of high voltage chip capacitors:

One type is temperature-compensated NPO medium, NP0, also known as COG, has very stable electrical properties and basically does not change with temperature, voltage, and time.It belongs to the ultra-stable, low-loss capacitor material type,it is suitable for high frequency, ultra high frequency and very high frequency circuits that require high stability and reliability.

The second type is high dielectric constant type X7R dielectric, X7R is a strong dielectric, so it can manufacture capacitors with larger capacity than NPO dielectric. The performance of this kind of capacitor is relatively stable. With the change of temperature and voltage time, its unique performance change is not significant. It belongs to the type of stable capacitor material, it is used in DC blocking, coupling, bypassing, filter circuits and medium and high frequency circuits with high reliability requirements.

The third type is semiconductor type X5R dielectric. X5R has a high dielectric constant and is often used to produce large-capacity capacitor products with large specific capacitance and high nominal capacity. However, its capacity stability is better than that of X7R, and its capacity and loss are more sensitive to test conditions such as temperature and voltage. It is mainly used in oscillation, coupling, filtering and bypass circuits in electronic complete machines.

Advantages: small package size, stable quality, high insulation performance, high voltage resistance; Disadvantages: small capacity, currently capped at 100UF, easy to be broken down by pulse voltage.

Performance parameters: 1. Material NPO(COG).X7R.X5R.Y5V; 2. Capacity 0.1PF-100PF-1NF-1UF-100UF; 3. Voltage 6.3V-100V-1KV-2KV-5KV; 4. Package 0201- 0805-1206-1812-2225.

Scope of application: The products are widely used in module power supply, automotive electronics, communication power supply, LED lighting power supply and other fields, and have broad application and development prospects.