Physical meaning of non-inductive capacitance

Non-inductive capacitors are designed with a winding structure that minimizes inductance, making them ideal for high-frequency applications. While no capacitor is completely free of inductance, the design ensures that the inductive effects are negligible at high frequencies. This makes them particularly useful in circuits where fast switching and high-speed performance are required.

Although many metallized film capacitors exhibit non-inductive properties, the term "non-inductive capacitor" typically refers to specific types used in power electronics, such as surge suppression capacitors for IGBT protection. These capacitors are optimized for handling high voltage and current spikes, which makes them unsuitable for general-purpose use like grid surge protection due to their specialized design and cost.

A key characteristic of non-inductive capacitors is their ability to handle large du/dt (rate of change of voltage) values, which means they can withstand high pulse currents without significant losses. They are commonly used in high-frequency applications, such as in the front-end of power supplies or in motor drives, where minimizing parasitic inductance is crucial for performance and reliability.

Non-inductive capacitors often have short or no leads, which further reduces their inductance. They are typically rated in picofarads (PF) and are designed to operate under extreme conditions. The term "no sense" here refers to the fact that these capacitors do not introduce unwanted inductance into the circuit, ensuring better signal integrity and stability. In a circuit where capacitance and inductance interact, this balance is essential for proper operation.

Non-Inductive Capacitor Products – MPA Series

The MPA series non-inductive capacitors are specifically engineered for high-voltage and high-current environments. They feature a polypropylene film dielectric, with a cylindrical core connected in a special electrode configuration. The core is wrapped with a plastic tape, and the ends are sealed with flame-retardant epoxy resin, providing excellent mechanical and electrical protection.

Key features include: - Extremely low self-inductance - Low equivalent series resistance (ESR) - High insulation resistance - Excellent frequency response - Ability to withstand high voltage and current surges

These capacitors are widely used in applications such as buffer circuits, energy conversion systems, switch-mode power supplies, and inverters. They are especially effective as snubber capacitors for IGBTs, thyristors, and Darlington transistors, where rapid voltage changes must be controlled to prevent damage to the components.

Main Parameters:

• Operating Temperature: -40°C to +70°C
• Capacitance Tolerance: ±10% (K), ±5% (J)
• Rated DC Voltage (VRDC): 630V, 1200V, 1600V, 2000V, 2500V, 3000V
• Rated AC Voltage (VRAC): 380V, 500V, 630V, 660V, 700V, 750V
• DC Surge Voltage (VPKDC): 2400V, 3000V, 3500V
• Test Voltage: 1.5 VRDC for 10 seconds at 25°C between leads; 2kV AC for 60 seconds at 25°C between lead and case
• Inherent Inductance: ≤ 1nH/mm (including lead length)
• Loss Tangent: ≤ 5×10⁻⁴ for CR ≤ 1.5μF at 1kHz; ≤ 8×10⁻⁴ for CR > 1.5μF at 1kHz
• Insulation Resistance: ≥ 30GΩ (60 seconds, 100V DC measurement)
• Capacitance Stability: -4% after 30,000 hours at rated DC voltage

These specifications make the MPA series an ideal choice for demanding industrial and power electronics applications where precision, reliability, and performance are critical.