The Function of Safety Capacitors
Safety capacitors play several important roles in electrical and electronic devices:
Power Line Filtering: Safety capacitors are commonly used in power lines to filter out high-frequency noise, reducing electromagnetic interference and improving circuit stability and reliability.
Isolation: These capacitors have high insulation capability, allowing them to isolate different circuits within a device from each other. This prevents high-voltage components from affecting low-voltage parts, thereby enhancing device safety.
Electrical Safety: Designed to meet specific electrical safety standards, safety capacitors protect users from voltage fluctuations in electrical equipment, ensuring safe operation.
Advantages of Capacitors
High Safety
Designed to international safety standards, they offer superior safety performance suitable for various electrical devices.
Good Stability
By filtering high-frequency noise on power lines, they enhance circuit stability and reliability.
Effective Isolation
They provide significant isolation between circuits on power lines, improving the electrical isolation performance of devices.
Disadvantages
Higher Cost
Compliance with stringent standards in design and manufacturing makes safety capacitors more expensive compared to standard capacitors.
Relatively Large Size
To achieve high insulation capability, safety capacitors are generally larger in size compared to some standard capacitors.
Differences: Safety capacitors discharge differently from standard capacitors; after the external power is disconnected, standard capacitors can retain charge for a long time, posing a shock hazard when touched, whereas safety capacitors do not have this issue. In AC power input applications, typically three safety capacitors are used to suppress EMI conducted interference.
Safety Capacitors Classification
Safety capacitors are primarily categorized into X and Y classes:
X Class Capacitors
Used for power line filtering, less sensitive to voltage fluctuations, suitable for use at the power input terminals.
Y Class Capacitors
Used internally to isolate different circuits within devices, more sensitive to voltage fluctuations, suitable for direct connection to internal circuits.
Safety Capacitors Typical Applications
Power Adapters
Widely used in power adapters to ensure stable and safe output voltage through filtering and isolation.
Electronic Device Power Inputs
Found at the power input terminals of various electronic devices to enhance stability and filtering performance.
Electrical Appliances
Extensively used in household appliances, office equipment, and other electrical devices to ensure safety and reliability.
Safety Capacitors in 220 V AC Input Circuit for Switching Power Supplies
As shown in the figure above is the X capacitor and Y capacitor application circuit, which is a 220 V AC input circuit for a switching power supply, also known as a transient filter circuit or known as an EMI filter. R1 in the circuit is a varistor, L1 and L2 are ferrite coils, and FU1 is a fuse.
The EMI filter is set between the 220 V AC inlet line and the rectifier circuit, which is used to filter out the voltage transient and high-frequency interference in the utility grid, and at the same time prevent the high-frequency interference generated by the switching tubes in the switching power supply from transmitting to the utility grid, forming a high-frequency interference to other electrical appliances.
Differential Mode High Frequency Interference Signal and X-Capacitor Circuit Analysis
There are two 220 V AC incoming wires, one is the fire wire and the other is the zero wire. These two lines will produce two kinds of high-frequency interference signals, namely, differential-mode high-frequency interference signals and common-mode high-frequency interference signals, as shown in the figure.
As can be seen from the figure, high-frequency interference signals U1 and U2 in the same direction, and they are equal in size, so that the two signals are called common-mode signals; high-frequency interference signals U3 and U4 in the opposite direction, and they are equal in size, so that the two signals are called differential mode signals.
Common mode high-frequency interference signal and Y capacitor circuit analysis
The figure below shows the Y capacitor to eliminate common mode high-frequency interference signal schematic, inhibit common mode high-frequency interference signal must be two Y capacitors, because the firewire and zero line have high-frequency interference signal.
The common-mode high-frequency interference signal on the fire line through the Y capacitor C1 to ground, the common-mode high-frequency interference signal on the zero line through the Y capacitor C2 to ground, so that the common-mode high-frequency interference signal can not be added to the back of the circuit, to achieve the purpose of the suppression of common-mode high-frequency interference signal.
About Us
UF Capacitors is an ISO9001-certified manufacturer in China, founded in 1995. We hold military qualifications for tantalum capacitors, MLCC, and other products. Additionally, we have a UL-recognized test laboratory located at our factory site.
Our marketing position is to provide a superior alternative to first-tier brands such as TDK, Murata, AVX, EPCOS, Vishay, and Panasonic. We offer similar quality but at better prices, with faster lead times and excellent service. With extensive experience working with renowned international companies like GE, Philips, Jabil, and Flex, we have built a strong reputation.
UF Capacitors serves the consumer electronics, computing, communications, and industrial markets. As a professional Chinese electronic components manufacturer, we are dedicated to delivering high-quality electronic components, exceptional management, strict quality control systems, and excellent sales service. We strive to foster mutually beneficial partnerships and drive business growth.
UF Capacitors Safety Capacitors Cross Reference
UF Capacitors’ safety capacitors have get the approvals of ENEC,UL,CQC,KC/KTL.
Both X and Y safety Capacitors are available.
Cross reference as below：
Y1Y2 Safety Capacitors Cross reference
|
Photo |
Descriptiom |
UF Capacitors' |
Vishay |
TDK/Epcos |
Murata |
AVX/Mallory |
|
|
Y1 Series |
30LVS Series |
CD45 Series |
DE1 Series |
K1Y Series |
|
|
|
Y2 Series |
WYO Series |
CS45 Series |
DE2 Series |
KJY Series |
X2 Safety Capacitors Cross Reference
|
Photo |
Description |
UF Capacitors |
Vishay |
Kemet |
|
|
X2 Series |
|
R46 Series |
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