In the context of a PCB (Printed Circuit Board), CY typically refers to a type of capacitor, specifically a safety capacitor used in EMI (Electromagnetic Interference) filtering. These capacitors are commonly found in power supplies and electronic devices to reduce interference and ensure safety when connected to the AC mains.
CY Capacitor (Y-Capacitor)
- Definition:
- CY capacitors, also known as Y-capacitors or Y-safety capacitors, are used to connect between live and ground or neutral and ground in a circuit. They help prevent electrical shock and filter high-frequency noise.
- They are classified as “safety capacitors” because they are designed to meet strict safety standards, ensuring that they do not fail in a way that could pose a risk to the user or the circuit.
- Function:
- CY capacitors are crucial in power line filtering to suppress noise and prevent the passage of harmful high-frequency interference from the power lines into the device.
- They provide isolation between high-voltage AC and ground to ensure safe operation.
- Classifications:
- Y1 Capacitors: Rated for higher voltage (typically up to 500VAC) and used in applications where greater safety margins are required.
- Y2 Capacitors: Rated for lower voltage (typically up to 250VAC) and used in less stringent environments.
- Applications:
- Used in AC-DC power supplies, chargers, and other equipment that connects directly to the mains.
- Commonly found in devices with a metal case, preventing users from receiving an electric shock if there is a fault.
- Important Characteristics:
- High Reliability: CY capacitors are designed to have high reliability and safety because they operate between live or neutral lines and ground.
- Low Capacitance: They usually have small capacitance values (typically in the picofarad range) to avoid drawing too much current, which could compromise safety.
- Safety Standards:
- CY capacitors are built to comply with international safety standards like IEC 60384-14, which sets the guidelines for their design, testing, and reliability.
- If a failure occurs, the capacitor is designed to break down safely without causing a short circuit or hazard.
Summary
- CY (Y-capacitors) are safety capacitors used in PCB designs, especially in power supply circuits, to filter out EMI and protect users from electrical shock. They are designed to handle high-voltage AC and are subject to strict safety standards.
