Can the safety capacitor be replaced by a common capacitor?
Safety capacitors are used in applications where the capacitor does not cause an electric shock and does not endanger personal safety. Safety capacitors are typically only used for filtering in anti-jamming circuits.
The discharge of the safety capacitor is different from the ordinary capacitor. The charge will remain for a long time after the external power supply is disconnected. If it is touched by hand, it will be charged, and the safety capacitor will not have this problem. For safety reasons and EMC considerations, it is recommended to add a safety capacitor at the power inlet.
At the AC power input, it is generally necessary to add three safety capacitors to suppress EMI conducted interference. They are used in the power supply filter to filter the power supply and filter the common mode and differential mode interference.
Y capacitance
Capacitors that are connected between the live and ground lines and between the neutral and ground lines are generally referred to as Y capacitors. The position of the two Y capacitors is critical, and it is necessary to comply with relevant safety standards to prevent leakage of the electronic equipment or the casing is charged, which may endanger personal safety and life. They are all safety capacitors, so the capacitance value must not be too large, and the withstand voltage must be high. Under normal circumstances, the machine operating in the subtropical zone requires that the earth leakage current should not exceed 0.7mA; working in a temperate machine requires that the earth leakage current should not exceed 0.35mA. Therefore, the total capacity of the Y capacitor generally cannot exceed 4700 PF (472).
The capacitance of the Y capacitor must be limited to control the magnitude of the leakage current flowing through it under the rated frequency and rated voltage and the effect on the EMC performance of the system. GJB151 specifies that the capacity of the Y capacitor should be no more than 0.1uF. In addition to the corresponding grid voltage withstand voltage, the Y capacitor also requires sufficient safety margin for electrical and mechanical performance to avoid breakdown and short circuit under extreme environmental conditions. The pressure resistance of the Y capacitor is correct. Protecting personal safety is of great significance.
In particular, as a Y capacitor for a safety capacitor, it is required to obtain certification from a safety inspection mechanism. The appearance of Y capacitors is mostly orange or blue, and is generally marked with safety certification marks (such as UL, CSA, etc.) and withstand voltage AC250V or AC275V. However, its true DC withstand voltage is as high as 5000V or more. It must be emphasized that the Y capacitor must not be used as a substitute for a common capacitor such as a nominal withstand voltage of AC250V or DC400V.
X capacitance
A capacitor connected in parallel between the live line and the neutral line is generally referred to as an X capacitor. Since the location of this capacitor connection is also critical, it also needs to comply with relevant safety standards. The X capacitor is also one of the safety capacitors. According to the actual needs, the capacitance of the X capacitor is allowed to be larger than the capacitance of the Y capacitor. However, a safety resistor must be connected in parallel with the X capacitor to prevent the power cord from being inserted and removed due to the charging and discharging process of the capacitor. The power cord plug is energized for a long time. The safety standard stipulates that when the working power cord is unplugged, the voltage charged at both ends of the power cord plug (or ground potential) must be less than 30% of the original rated operating voltage within two seconds.
The X capacitor, which is one of the safety capacitors, is also required to be certified by a safety inspection mechanism. X capacitors are generally marked with a safety certification mark and withstand voltage AC250V or AC275V, but its true DC withstand voltage is as high as 2000V or more. When using it, do not use the ordinary capacitors such as AC250V or DC400V at random.
In general, X-capacitors use a polyester film capacitor with a large ripple current. This type of capacitor is bulky, but it allows a large amount of current to be instantaneously charged and discharged, and its internal resistance is correspondingly small. The common capacitor ripple current has a low index and a high dynamic internal resistance. Replacing the X capacitor with a common capacitor, in addition to the capacitor withstand voltage can not meet the standard, the ripple current index is also difficult to meet the requirements.
Watch Screen Protector features a stretchable and retractable TPU Screen Protector that resists air bubbles and fingerprints on your device's screen and provides maximum protection for your device from scratches. The Hydrogel Film repairs screen scratches on its own and is ideal for curved curved screens.
Full Coverage: The soft material matches the edges of the watch screen well. Full coverage provides better protection and looks very discreet.
Oleophobic and waterproof: The oleophobic waterproof transparent layer can prevent the residue of sweat and grease, resist fingerprints, and keep the phone screen as new as ever.
Sensitive touch: only 0.14mm thick ultra-thin protective layer will not interfere with touch screen commands, your touch screen can still operate 100% normally.
If you want to know more information about Smart Watch Screen Protector products, please click the product details to view the parameters, models, pictures, prices and other information of Watch Screen Protector products.
Whether you are a group or an individual, we will do our best to provide you with accurate and comprehensive information about Watch Hydrogel Screen Protectors!
Watch Screen Protector, Watch Hydrogel Screen Protector,Smart Watch Screen Protector,Watch Protective Film,Apple Watch Screen Protector,Watch Screen Protector Cover
Shenzhen Jianjiantong Technology Co., Ltd. , https://www.jjthydrogelprotector.com