BFC237520243 vs F339MX246831MII2B0
| Part Number |
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| Category | Film Capacitors | Film Capacitors |
| Manufacturer | Vishay Beyschlag/Draloric/BC Components | Vishay Beyschlag/Draloric/BC Components |
| Description | CAP FILM 0.024UF 5% 1KVDC RADIAL | CAP FILM 0.68UF 20% 630VDC RAD |
| Package | Bulk | Bulk |
| Series | KP/MKP 375 | F339M |
| Features | - | - |
| Operating Temperature | -55°C ~ 105°C | -55°C ~ 110°C |
| Mounting Type | Through Hole | Through Hole |
| Package / Case | Radial | Radial |
| Applications | High Pulse, DV/DT | EMI, RFI Suppression |
| Tolerance | ±5% | ±20% |
| Size / Dimension | 1.024" L x 0.276" W (26.00mm x 7.00mm) | 1.024" L x 0.335" W (26.00mm x 8.50mm) |
| Termination | PC Pins | PC Pins |
| Voltage Rating - AC | 400V | 310V |
| Voltage Rating - DC | 1000V (1kV) | 630V |
| Lead Spacing | 0.394\" (10.00mm) | 0.886\" (22.50mm) |
| Ratings | - | X2 |
| Height - Seated (Max) | 0.787\" (20.00mm) | 0.709\" (18.00mm) |
| Capacitance | 0.024 µF | 0.68 µF |
| ESR (Equivalent Series Resistance) | - | - |
| Dielectric Material | Polypropylene (PP), Metallized | Polypropylene (PP), Metallized |
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1. Is a film capacitor AC or DC?
AC, DC
Film capacitors can be used in both AC and DC circuits. According to the current type, film capacitors can be divided into DC film capacitors and AC film capacitors.
DC film capacitors
DC film capacitors are mainly used in DC circuits and have the following characteristics:
Large capacity: has a higher capacitance.
Low withstand voltage: the withstand voltage value is relatively low.
Polarity: has positive and negative poles.
Application scenarios: commonly used in motor drives, uninterruptible power supplies (UPS), solar inverters, electronic ballasts, small automotive motors, household appliances, etc.
AC film capacitors
AC film capacitors are mainly used in AC circuits and have the following characteristics:
Small capacity: relatively small capacitance.
High withstand voltage: high withstand voltage value.
Pass AC, block DC: conduct electricity in AC circuits, equivalent to open circuits in DC circuits.
Application scenarios: widely used in industrial AC power supplies, asynchronous motor starting and operation, uninterruptible power supplies (UPS) and output filters of photovoltaic inverters, etc. -
2. Will the performance of film capacitors degrade?
Yes
The performance of film capacitors will degrade. The performance degradation of film capacitors is mainly due to their internal structure and material properties.
Reasons for performance degradation
Metal plating oxidation: During the capacitor manufacturing process, there is a trace amount of air between the film layers, which may be ionized under the action of the electric field to produce ozone. Ozone is a strong oxidant that oxidizes the metal plating to produce non-conductive metal oxides, resulting in a reduction in the plate area and a decrease in the capacitor capacity.
Humid air: During the winding process of film capacitors, if the workshop environment is not properly controlled, there will be a large amount of humid air. These humid air will produce air ionization reactions when the capacitor is working, generating ozone, which further causes the capacitor capacity to decay.
Poor quality materials: The film materials used are of poor quality, such as uneven evaporation and defects on the film, which will cause the capacitor capacity to decay.
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3. How do film capacitors fail?
High working environment temperature, improper selection of working current, exceeding the specified working voltage, harmonic current
The main reasons for film capacitor failure include the following:
High working environment temperature: Film capacitors can work normally in a temperature environment of -40℃~+105℃, but exceeding this range will accelerate thermal aging, resulting in a shortened service life, and even bursting in severe cases.
Improper selection of working current: The current value in the circuit should be less than the current value allowed by the film capacitor, otherwise it will cause the capacitor to heat up, and long-term use will shorten the life, and even burst in severe cases.
Exceeding the specified working voltage: Excessive voltage will cause partial discharge, which will then break down the capacitor and cannot be used.
There are harmonic currents: high-order harmonic currents are superimposed on fundamental currents, resulting in an increase in total current, causing capacitor load overload, internal expansion, and explosion.
Buying inferior capacitors: In order to reduce costs, some manufacturers on the market use low-quality materials to produce capacitors, which greatly reduces the actual withstand voltage and life of such capacitors.
The structural characteristics of film capacitors and the impact of the use environment on their performance:
Film capacitors are usually composed of polypropylene film, aluminum foil and plastic shell. Polypropylene film is sensitive to high temperature, which accelerates its aging and shortens the life of the capacitor. In addition, a humid environment will also cause water vapor to enter the capacitor, affecting its performance.
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4. What is the difference between foil capacitors and film capacitors?
Electrode materials, structure, and application areas
The main difference between foil capacitors and film capacitors lies in electrode materials, structures, and application areas.
Electrode materials and structures
Foil capacitors: Foil capacitors usually use metal foil as electrodes. This electrode is formed on a plastic film by vacuum evaporation, which is called a metallized film. This structure can save the thickness of the electrode foil, thereby reducing the volume of the capacitor and making it more miniaturized.
Film capacitors: Film capacitors use plastic films as dielectrics. Common plastic films include polyethylene, polypropylene, polystyrene or polycarbonate. These films overlap at both ends and are rolled into a cylinder to form a capacitor.
