Safety capacitor

Safety capacitor(Metal Oxide Varistor) for such occasions, that the failure of the capacitor would not lead to electric shock, do not endanger the personal safety which includes the X capacitor and Y capacitors. x capacitance is connected across the capacitance between the two lines in the power line (LN), generally used in the metal thin film capacitor; The Y-capacitor is connected across the capacitance between the two lines and the ground of the power line (LE, NE), and generally occur in pairs . Based on the leakage current limit, the the Y capacitor value can not be too large, the general X capacitor uF level, Y capacitor is nF level. X capacitor differential mode interference suppression. The Y capacitor suppress common mode interference.

The safety capacitor security level

Permissible peak pulse voltage the safety capacitor security level applications overvoltage level (with the IEC664)

  

X1> 2.5kV ≤ 4.0kV Ⅲ

X2 ≤ 2.5kV Ⅱ

X3 ≤ 1.2kV -

A safety capacitor security level type of insulation rated voltage range

Y1 double insulation or reinforced insulation ≥ 250V

Y2 basic or supplementary insulation ≥ 150V ≤ 250V

Y3 basic or supplementary insulation ≥ 150V ≤ 250V

The Y4 basic or supplementary insulation <150V

The Y capacitor capacitance must be limited, so as to control the role of the rated frequency and rated voltage flowing through its leakage current size and the purpose of the system EMC performance. GJB151 provisions of the Y-capacitor should be no greater than 0.1uF. Y capacitor in addition to complying with the corresponding grid voltage withstand requirements of this capacitor in the electrical and mechanical properties sufficient safety margin to avoid short-circuit breakdown phenomena under extreme environmental conditions, Y capacitor voltage performance on protect the personal safety of great significance.(Metal Oxide Varistor)

Precautions

Capacitor for electromagnetic interference suppression

When the capacitor to eliminate noise in the power supply across the line circuit, not just the normal voltage, must also take into account the generation of abnormal pulse voltage (such as lightning), this capacitor may cause smoke or fire. So, across line capacitor safety standards for strict regulations in different countries, it must be used the safety certification capacitor.

Does not allow the DC capacitor used as a cross-line capacitor

For X2 electromagnetic interference suppression should be applied to not result in failure of the capacitor a shock hazard occasions, such as power cross-line connection, can withstand 2.5kV pulse voltage capacitor.

Y2 class electromagnetic interference suppression capacitor should be applied to the occasion of shock hazard, do not result in the failure of the capacitor for the power cross-line connection, can withstand 5kV pulse voltage shock, thus preventing the breakdown phenomena.

The safety capacitor IEC standard, advanced production technology and strict quality assurance system.

According to IEC 60384-14, the capacitor divided into X capacitors and Y capacitors the X capacitor capacitor cross the LN Y capacitor is a cross between the LG / NG capacitors. (L = Line, N = Neutral, G = Ground)

X capacitor bottom divided into X1, X2, X3, main difference is that: 1. X1 resistance to high pressure is greater than 2.5 kV, less than or equal to 4 kV the X2 high pressure resistance less than or equal to 2.5 kV, 3. X3 high pressure resistance less than equal to 1.2 kV

Y capacitor is divided into under the Y1, Y2, Y3, Y4, main difference is that: 1. Y1 8 kV high voltage is greater than 2. Y2 resistance to high pressure greater than 5 kV, 3 Y3 resistant high n / a 4 Y4 resistant high pressure greater than 2.5 kV

X, Y capacitor are safety capacitors, FireWire zero line between the X-capacitor, FireWire and ground Y capacitors are used in the power supply filter, play power filtering effect, respectively, of the common mode and differential mode interference from the filtering effect. safety capacitor for such occasions, that the failure of the capacitor will not lead to electric shock, do not endanger their personal safety. peak pulse voltage the safety capacitor security level application allows the over-voltage level (with the IEC664) X1> 2.5kV ≤ 4.0kV Ⅲ X2 ≤ 2.5kV Ⅱ X3 ≤ 1.2kV - the safety capacitor rated voltage range of the security level of insulation type Y1 double insulation or reinforced insulation ≥ 250V Y2 basic or supplementary insulation ≥ 150V ≤ 250V Y3 basic insulation or additional Insulation ≥ 150V ≤ 250V Y4 basic or supplementary insulation <150V Y capacitance of the capacitor must be restricted so as to control the effect of the rated frequency and rated voltage, flow through its leakage current size and performance of the system EMC purposes . GJB151 provisions of the Y-capacitor should be no greater than 0.1uF. Y capacitor in addition to complying with the corresponding grid voltage withstand requirements of this capacitor in the electrical and mechanical properties sufficient safety margin to avoid short-circuit breakdown phenomena under extreme environmental conditions, Y capacitor voltage performance on protect the personal safety significance

X capacitor filter circuit is jumper the LN-line; Y capacitor is NG line. The safety standards pulse voltage points X1, X2, X3 capacitance; insulation class points Y1, Y2, Y3 points. (None of these points is what material to learn more later.) As for the safety standards of various countries, there are some differences, but the rated voltage of no more than 250 and 400. The safety capacitor major manufacturers do is to meet the demand of the safety standards, a safety capacitor to meet the requirements of the Y capacitor, can be made to meet the requirements of the X capacitor. So there is the the safety capacitor superscript X1Y1, X1Y2 ...(Metal Oxide Varistor)

Indirect FireWire and 0 line capacitor is X, the FireWire and ground indirect capacitor like Y. Directly as FireWire and 0 line capacitance affected by the voltage peak to avoid the pressure rating of the short-circuit, pay more attention to the parameters, not set limits on the capacitance value. FireWire and direct ground capacitance leakage security problems related to its focus on the parameters insulation levels, as james bai said much capacitance values ​​will power outage on the devices of the people have an impact.

Safety certification

As security Y capacitor capacitance requirements must obtain a safety certification testing organizations. The Y capacitor appearance of orange or blue, are generally marked with a safety certification mark (such as UL, CSA logo) and pressure AC250V or AC275V words. However, the real DC withstand voltage up to 5000V. It must be emphasized that the Y-capacitor are not free to use the alternative nominal pressure AC250V or DC400V like ordinary capacitor.

2, also require safety testing organization must obtain certification as a security one X capacitor capacitance. X capacitors are generally marked with a safety certification mark and pressure AC250V or AC275V words, but its true DC withstand voltage up to 2000V nominal pressure AC250V or DC400V like ordinary capacitor to substitute when not free to use.

Breakdown problems

Cx capacitor filter if the breakdown, equivalent to the AC power grid short circuit, at least cause the device to stop working; capacitor Cy breakdown, equivalent to the AC grid voltage is applied to the casing of the device, a direct threat to the personal safety, and spread metal shell reference circuit or equipment safety, and often leads to some of the circuit or equipment burned.

Actual needs

X capacitor value according to actual needs, allowing larger than the Y-capacitor value, but must be a safety resistor in parallel at both ends of the X capacitor used to prevent When plugging or unplugging the power cord, the process of charging and discharging of the capacitor cause the power cord long charged. Prescribed safety standards when working into the machine power cord is unplugged, within two seconds, the charged voltage across the power cord (or ground potential) must be less than 30% of the original nominal operating voltage.(Metal Oxide Varistor)