Special note: as a safety capacitor Y capacitors, the requirements must be certified by the safety testing organizations. Y capacitors are mostly orange or blue in appearance, generally marked with safety certification mark (such as UL, CSA, etc. mark) and withstand voltage AC250V or AC275V words. However, its true DC withstand voltage up to 5000V or more. It must be emphasized that Y capacitors should not be used arbitrarily, such as nominal withstand voltage AC250V or DC400V ordinary capacitors to substitute.
In parallel between the fire wire and zero line suppression of capacitance, generally known as X capacitance. Because this capacitor is connected to the location of the more critical, also need to comply with the relevant safety standards. x capacitor also belongs to the safety of one of the capacitors. According to the actual need, X capacitance is allowed to be larger than the capacitance of Y capacitance, but at this time must be connected in parallel with a safety resistor at both ends of the X capacitance, used to prevent the power cord unplugged, due to the capacitance of the process of charging and discharging the power cord plug for a long time with the electricity. Safety standards require that when the power cord is unplugged from a working machine, within two seconds, the voltage (or potential to ground) charged at both ends of the power cord plug must be less than 30% of the original rated operating voltage.
As one of the safety capacitors X capacitors, but also required to obtain the certification of the safety testing organizations. X capacitors are generally marked with the safety certification mark and the withstand voltage AC250V or AC275V words, but its real DC withstand voltage up to 2000V or more, do not use the time to use the nominal withstand voltage AC250V or DC400V and other ordinary capacitors to substitute.
Usually, the X capacitors are selected to withstand the ripple current is relatively large polyester film capacitors. This type of capacitor, the volume is larger, but it allows instantaneous charging and discharging of the current is also very large, and its internal resistance is correspondingly small. Ordinary capacitors have low ripple current indicators and high dynamic internal resistance. Using ordinary capacitors instead of X-capacitors, in addition to the capacitive withstand voltage can not meet the standard, the ripple current index is also difficult to meet the requirements.
According to IEC 60384-14, capacitors are categorized into X-capacitors and Y-capacitors, 1. X-capacitors are capacitors spanning between L-N and 2. Y-capacitors are capacitors spanning between L-G/N-G. (L=Line, N=Line, N=Line, N=Line, L=Line, N=Line). (L=Line, N=Neutral, G=Ground)
X capacitors are divided into X1, X2, X3, the main difference is: 1. X1 withstand high voltage is greater than 2.5 kV, less than equal to 4 kV, 2. X2 withstand high voltage is less than equal to 2.5 kV, 3. X3 withstand high voltage is less than equal to 1.2 kV
Y capacitors are divided into Y1, Y2, Y3, Y4, the main difference is: (DC voltage level)
1. Y1 withstand high voltage greater than 8 kV, 2. Y2 withstand high voltage greater than 5 kV, 3. Y3 withstand high voltage n/a 4. Y4 withstand high voltage greater than 2.5 kV they are used in the power supply filter, play a role of power supply filtering, respectively, on the ****-mode, the difference between the mode of the work of the disturbance to the filtering effect.
Safety capacitors are used in situations where the failure of a capacitor does not result in an electric shock and does not jeopardize personal safety. It includes x-capacitor and y-capacitor. X capacitance is the capacitance across the power line between the two lines (L-N), generally choose the metal film capacitor; Y capacitance is the capacitance across the power line between the two lines and the ground respectively (L-E, N-E), generally appear in pairs. Based on the leakage current limitation, Y capacitance value can not be too large, generally X capacitance is uF level, Y capacitance is nF level. X capacitance suppresses the differential mode interference, Y capacitance suppresses **** mode interference. Safety level of safety capacitors Safety level of safety capacitors? Peak pulse voltage allowed in the application? Overvoltage class (IEC664) X1? >2.5kV ≤4.0kV? Ⅲ X2? ≤2.5kV? Ⅱ X3? ≤1.2kV -- Safety class of safety capacitors? Insulation type? Rated voltage range Y1? Double insulation or reinforced insulation? ≥ 250V Y2? Basic or additional insulation ≥ 150V ≤ 250V Y3? Basic or additional insulation ≥ 150V ≤ 250V Y4? Basic or additional insulation <150V
Y The capacitance of capacitors must be limited to achieve the control of the rated frequency and the rated voltage, the size of the leakage current flowing through it and the impact on the system EMC performance. GJB151 stipulates that the capacity of Y capacitor should be no more than 0.1uF. In addition to meeting the corresponding grid voltage withstand voltage, Y capacitors are also required to have enough safety margins in electrical and mechanical properties, to avoid breakdown and short-circuit phenomena in extremely harsh environmental conditions, Y capacitor's voltage withstand performance is of great significance to the protection of personal safety.
The capacitance of Y capacitor must be limited, so as to achieve the control in the rated frequency and rated voltage, the leakage current flowing through the size of it and the purpose of the impact on the EMC performance of the system. GJB151 stipulates that the capacity of Y capacitor should be not more than 0.1uF. Y capacitor in addition to meet the corresponding grid voltage withstand voltage, but also requires that this capacitor in the electrical and mechanical properties of the sufficient safety margin, to avoid extreme harsh environmental conditions of breakdown short-circuit phenomenon, the Y capacitance is important to protect personal safety. Safety margin, to avoid breakdown short-circuit phenomenon in extremely harsh environmental conditions, Y capacitor voltage resistance performance is important for the protection of personal safety