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electronic components and devices
Y1 capacitors-function , application and comparison

SMD capacitors are one of the most common capacitors in electronic circuits, and Y1 capacitors are one of the types, which are widely used in the circuits of various electrical equipment and household appliances. This article will detail the characteristics of Y1 capacitors, their applications, comparison withY2 capacitor, and how to properly select and use them.

Table of Contents

What is Y1 capacitor

What is Y1 capacitor
What is Y1 capacitor ?

In applications such as home appliances, power supplies, motors, and power tools, noise and EMI interference on power lines are numerous and complex, and must be filtered out with capacitors. At the AC power input, it is generally necessary to add 3 safety capacitors (Safety Capacitor) to suppress EMI conducted interference, and these capacitors will not cause electric shock after failure, and will not endanger personal safety.

According to the requirements of IEC 60384-14, safety capacitors are divided into X capacitors and Y capacitors, which filter common-mode and differential-mode interference, respectively. Among them, the X capacitor spans between the two lines of the power line (L-N), and the Y capacitor is connected between the two power lines and the ground (L-E, N-E), and the X capacitor and Y capacitor only indicate the use location, not the material of the capacitor.

What is the function of the Y capacitor

There are three main functions of the Y capacitor:

1. Current compensation: the capacitor element can compensate for the instantaneous current generated by the change of the load, and when the load is adjusted in time, the capacitance of the Y capacitor can change the size of the current, so that the circuit works in the most ideal state.

2. Filter: Y capacitor can store and release electrical energy, which can be used to filter out unwanted electricity or signals.

3. Impedance compensation: Y capacitor can effectively compensate the impedance of the reactor to prevent pulse signal or similar power interference, and it can also compensate for the capacitance change of the distributed capacitor.

What’s the characteristic of Y1 capacitors

Y1 capacitors have relatively high voltage levels and large capacities. They are capable of withstanding the surge voltage between the 220V alternating current (AC) power input line and the device housing. This makes the Y1 capacitor a reliable surge suppression component in electrical circuits. In addition, Y1 capacitors have good high-temperature stability and high-frequency response characteristics, and can operate in high-temperature and high-frequency environments.

What’s the application of Y1 capacitors

In circuit applications, Y1 capacitors are often used to protect other components in a circuit from overload voltages and surge voltages caused by, for example, inductor step-down. They also act as power isolation capacitors to prevent unclean AC signals on the power line from affecting circuit performance. In addition, Y1 capacitors can also be used in radio transmission systems, computer peripherals, motor protection devices, power switches, dimming lights, LED lighting and white goods.

How to select and use Y1 capacitors

When we want to select and use Y1 capacitors, there are some important factors to consider.

First, we need to know the voltage and capacity range required by the circuit. We also need to pay attention to the appearance dimensions of Y1 capacitors to ensure that they meet our application requirements.

In addition, we need to select a standard-compliant Y1 capacitor according to the specified power isolation standard.

Finally, we need to select the working capacitance and voltage level of the Y1 capacitor according to the high temperature environment and high frequency environment generated by the circuit.

In short, SMD Y1 capacitor is one of the basic components in electronic circuits, with high voltage level and capacity, widely used in household appliances and various electrical equipment. When correctly selecting and using Y1 capacitors, we need to consider factors such as the voltage and capacity requirements of the circuit, the appearance size, the power isolation standard, and the high temperature and high frequency environment. Only in the case of correct selection and use, we can give full play to the role of Y1 capacitors to ensure the stability and reliability of electrical circuits.

What is the difference between Y1 and Y2 capacitors

safety capacitor-Y1 capacitor and Y2 capacitor

1. The pitch is different

The conventional pitch of the Y1 capacitor is 10mm;

The typical pitch of the Y2 capacitor is 7.5mm.

2. The withstand voltage is different

The rated voltage of Y1 capacitor is 500VAC, withstand voltage can reach 4000VAC;

The rated voltage of Y2 capacitor is 500VAC, and the withstand voltage reaches 1800-2600VAC.

3. The insulation is different

The Y1 capacitor belongs to double insulation (JD);

The Y2 capacitors are basic insulation (JY).

4. Different application

The Y1 capacitor is used to span the primary and secondary sides;

The Y2 capacitor is used to protect the earth, that is, the FG line, across the secondary side.

5. The volume is different

In the case of the same capacity, the volume of the safety Y1 capacitor is appropriately larger than the safety Y2 capacitor.


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Y1 capacitor is a kind of safety capacitors.The Y capacitor is connected between the two power lines and the ground (L-E, N-E).

1. Current compensation
2. Filter
3. Impedance compensation

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