BFC238351333 vs MKT1820468636
| 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 0.033UF 5% 1.6KVDC RAD | CAP FILM 0.68UF 20% 630VDC RAD |
| Package | Bulk | Bulk |
| Series | MMKP383 | MKT1820 |
| Features | - | - |
| Operating Temperature | -55°C ~ 105°C | -55°C ~ 125°C |
| Mounting Type | Through Hole | Through Hole |
| Package / Case | Radial | Radial |
| Applications | High Pulse, DV/DT | DC Link, DC Filtering |
| Tolerance | ±5% | ±20% |
| Size / Dimension | 1.024" L x 0.394" W (26.00mm x 10.00mm) | 1.240" L x 0.531" W (31.50mm x 13.50mm) |
| Termination | PC Pins | PC Pins |
| Voltage Rating - AC | 550V | 220V |
| Voltage Rating - DC | 1600V (1.6kV) | 630V |
| Lead Spacing | 0.886\" (22.50mm) | 1.083\" (27.50mm) |
| Ratings | - | - |
| Height - Seated (Max) | 0.768\" (19.50mm) | 0.925\" (23.50mm) |
| Capacitance | 0.033 µF | 0.68 µF |
| ESR (Equivalent Series Resistance) | - | - |
| Dielectric Material | Polypropylene (PP), Metallized | Polyester, 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. Are film capacitors better than electrolytic capacitors?
Not necessarily
Film capacitors and electrolytic capacitors each have their own advantages and disadvantages, and the specific choice depends on the application scenario.
Advantages of film capacitors
Non-polarity: Film capacitors are non-polar, and there is no need to distinguish between positive and negative poles, avoiding the risk of capacitor explosion due to reverse connection.
Long life: Film capacitors have significantly longer life and better stability.
Wide temperature range: Film capacitors have a wide operating temperature range, generally -40℃~+105℃/110℃, suitable for various ambient temperatures.
High withstand voltage: Film capacitors can withstand overvoltages higher than 1.5 times the rated voltage in a short period of time, and have strong withstand voltage.
Low loss: Film capacitors have low loss and are suitable for high-frequency circuits, especially for occasions requiring low loss and high-frequency applications.
Advantages of electrolytic capacitors
Large capacity: Electrolytic capacitors usually have large capacitance and are suitable for occasions requiring large amounts of energy storage.
Low cost: The cost of electrolytic capacitors is relatively low, suitable for occasions with strict cost requirements.
High energy density: Electrolytic capacitors are a strong choice when cost-effective, high-capacity energy storage is required, especially when maintaining DC output voltage during power outages.
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3. Can film capacitors be used for AC?
Yes
Film capacitors can be used for AC. Film capacitors can work normally in AC circuits and have specific application scenarios and advantages.
Structure and working principle of film capacitors
Film capacitors are mainly composed of metal foil (or foil obtained by metallizing plastic) as electrode plates and plastic film as dielectric. Common plastic films include polyethylene, polypropylene, polystyrene or polycarbonate. These capacitors are usually made by winding or stacking processes to form a cylindrical structure. -
4. 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.
