
Class-X and Class-Y capacitors are safety-certified and generally designed and used in AC line filtering in many electronic device applications. These safety capacitors are also known by other names, including EMI/RFI suppression capacitors and AC line filter safety capacitors. (EMI stands for electromagnetic interference. . Class-X and Class-Y capacitors are classified according to: 1. their peak voltage/rated voltage and 2. the peak impulse voltage that they can safely withstand. Tables 1 and 2. . Subclass X2 and Y2 are the most commonly used safety-certified capacitors. Depending upon your own application and requirements, they are. . Because Class-X and Class-Y capacitors must be connected directly to AC lines (line-to-neutral or line-to-ground) in order for them to perform their EMI and RFI filtering functions, they must be rated and certified as "safety. . All safety-certified capacitors should have the proper logo markings/symbols on their casing. See Figure 4 below for an example and see Figure 5 for a definition/description of these logos: [pdf]

Taking the three capacitor values from the above example, we can calculate the total equivalent capacitance, CTfor the three capacitors in series as being: One important point to remember about capacitors that are connected together in a series configuration. The total circuit capacitance ( CT ) of any number of. . Find the overall capacitance and the individual rms voltage drops across the following sets of two capacitors in series when connected to a 12V. . Then to summarise, the total or equivalent capacitance, CT of a circuit containing Capacitors in Seriesis the reciprocal of the sum of the reciprocals of all of the individual capacitance’s added together. Also for capacitors. [pdf]
This capacitive reactance produces a voltage drop across each capacitor, therefore the series connected capacitors act as a capacitive voltage divider network. The result is that the voltage divider formula applied to resistors can also be used to find the individual voltages for two capacitors in series. Then:
We have seen here that a capacitor divider is a network of series connected capacitors, each having a AC voltage drop across it. As capacitive voltage dividers use the capacitive reactance value of a capacitor to determine the actual voltage drop, they can only be used on frequency driven supplies and as such do not work as DC voltage dividers.
The two capacitors which are connected in series have the capacitance values of 10uF and 22uF respectively. Here the circuit voltage is 10V,this voltage is distributed between both capacitors. In the series connection all the capacitors have same charge (Q) on it but the supply voltage (V S) is not same for all capacitors.
Because as we now know, the reactance of both capacitors changes with frequency (at the same rate), so the voltage division across a capacitive voltage divider circuit will always remain the same keeping a steady voltage divider.
Every capacitor will 'see' the same voltage. They all must be rated for at least the voltage of your power supply. Conversely, you must not apply more voltage than the lowest voltage rating among the parallel capacitors. Capacitors connected in series will have a lower total capacitance than any single one in the circuit.
But just like resistive circuits, a capacitive voltage divider network is not affected by changes in the supply frequency even though they use capacitors, which are reactive elements, as each capacitor in the series chain is affected equally by changes in supply frequency.

Power capacitors are electrical energy storage devices, thus you must always handle them with caution. Even if they are turned off for a long period of time, capacitors might still be charged with high voltage, and this may be lethal. For this reason, please be extremely careful when handling capacitors and electrically. . The most frequent risk factors which cause capacitor damage and possible failure of the internal protective devices are: 1. Exceeding the. . Never use capacitors that have dents of more than 1 mm depth or any other mechanical damage. This applies also in cases of leakage. To ensure the functionality of the overpressure disconnector, do not. . The capacitor manufacturer cannot predict every possible stress which a power capacitor may be subjected to, and which has to be taken into account in a proper design. This means that the user bears crucial co-responsibility.. [pdf]
The shelf life of most capacitors depends on environment factors such as humidity, temperature, and atmospheric pressure. Subjecting capacitors to harsh conditions can significantly affect their electrical properties, or even damage them completely.
Ceramic capacitors should be stored at temperature and humidity conditions specified by the manufacturer. Before using a capacitor, you should check the recommended shelf life, date of receipt, and inspect terminations. For most capacitors, the shelf life is significantly determined by storage conditions.
( 2 ) Operating temperature and applied ripple current shall be within the specification. qThe capacitor shall not be used in an ambient temperature which exceeds the operating temperature specified in the specification. wDo not apply excessive current which exceeds the allowable ripple current.
The electrical characteristics that are affected when these capacitors are stored for a long time without charge are equivalent series resistance (ESR), leakage current, and capacitance. ESR and leakage current increase while capacitance decreases. Nevertheless, the changes are small if these capacitors are stored at room temperature.
Before using a capacitor, it is important to check its receipt time. Some capacitors require reforming after they have been stored for an extended period of time without recharge. To maximize the life of capacitors, they should be stored under conditions specified by the manufacturer.
Subjecting capacitors to harsh conditions can significantly affect their electrical properties, or even damage them completely. The effect of environmental factors on the shelf life of capacitors varies depending on the chemical composition and construction of a capacitor.
Committed to delivering cutting-edge energy storage technologies,
our specialists guide you from initial planning through final implementation, ensuring superior products and customized service every step of the way.