Kingtronics Blog

Kingtronics International Company — Inspired by Innovation

Reliable Film Capacitor Solution for Snubber and Pulse Applications
Kingtronics FKT-SA double-sided metallized polypropylene film capacitors for pulse and high voltage designs

When designing high-voltage or high-frequency systems, engineers frequently confront one major challenge: finding a capacitor that delivers predictable performance under demanding pulse and snubber conditions. Many film capacitors look sufficient on paper—but when exposed to fast discharge events, elevated temperatures, and repeated cycles, issues such as rising dissipation, capacitance shift, or insulation degradation can appear in real operation.

The Kingtronics FKT-SA Series is specified as a double-sided metallized polypropylene film capacitor with a non-inductive configuration. According to the datasheet, it offers low loss and small inherent temperature rise, a negative temperature coefficient of capacitance, and an epoxy resin dip-sealed construction for flame-resistant circuits. It is referenced to IEC 61071 and designed for high voltage, high frequency and pulse applications, lamp capacitors for electronic ballast compact lamps, and snubber / SCR commutation circuits.

View FKT-SA Product Page →

Key Technical Characteristics
Datasheet-based parameters for engineering selection

• Double sided metallized polypropylene structure with non-inductive configuration.
• Low loss and small inherent temperature rise; negative temperature coefficient of capacitance.
• Reference Standard: IEC 61071.
• Climatic Category: 40 / 105 / 56.
• Operating temperature range: −40 °C to +105 °C.
• Rated temperature range:
  • up to +85 °C for rated DC voltage (VR(DC))
  • up to +75 °C for rated AC voltage (VR(AC))
• Derating above these points: from +85 °C to +105 °C for DC, and from +75 °C to +105 °C for AC, with a decreasing factor of 1.25% per °C for VR.
• Rated voltages: 250 V, 400 V, 630 V, 1000 V, 1600 V, 2000 V.
• Capacitance range: 0.00022 µF to 3.9 µF.
• Capacitance tolerance options: ±2%, ±3%, ±5%, ±10%, ±20%.
• Voltage proof: 1.60 UR (5 s).
• Dissipation factor: ≤ 0.0010 @ 1 kHz, 20 °C.
• Insulation resistance at 20 °C, 100 V, 1 min:
  • CR ≤ 0.33 µF: ≥ 50 000 MΩ
  • CR > 0.33 µF: ≥ 15 000 s

Typical Applications
High voltage, high frequency and pulse circuits, snubber and lamp capacitor use

The FKT-SA Series is listed for the following application areas in the datasheet:

• High voltage, high frequency and pulse circuits.
• Lamp capacitor for electronic ballast compact lamps.
• SNUBBER and SCR commutation circuits.

Temperature and Frequency Characteristics
Capacitance, dissipation, operating voltage and insulation behaviour

The FKT-SA datasheet includes charts that show how capacitance, dissipation factor, operating voltage and insulation resistance behave over temperature, as well as capacitance and dissipation vs. frequency. These curves give engineers a reference for estimating capacitor behaviour in high voltage, high frequency and pulse circuits when actual operating conditions differ from nominal test points.

FKT-SA Pulse and Snubber Application Video
Overview of Kingtronics FKT-SA film capacitor series

The following video introduces the Kingtronics FKT-SA film capacitor series and highlights how this double-sided metallized polypropylene construction can be used in pulse and snubber applications.

FKT Series Catalog for Sourcing and Design
Family overview and detailed electrical ratings

Procurement Considerations for Engineers & Buyers
Matching rated values, derating curves and application requirements

When specifying film capacitors for pulse and snubber applications, engineers and procurement teams typically review:

• Rated voltage and capacitance ranges appropriate for the target circuit.
• Operating temperature range and the stated derating factors vs. temperature.
• Dissipation factor and insulation resistance under specified test conditions.
• Climatic category and reference standard (IEC 61071 for FKT-SA).

Because these parameters are clearly listed in the FKT-SA datasheet, the series can be evaluated and compared against the electrical and environmental requirements of high voltage, high frequency and pulse systems.

Final Notes

For applications involving high-voltage pulses, snubber networks or high-frequency switching, the Kingtronics FKT-SA Series provides a double-sided metallized polypropylene film capacitor option with clearly defined ratings and characteristics for engineering evaluation.

Kingtronics International Company — Inspired by Innovation

The Kingtronics® XKT Metal Oxide Varistor (MOV) Series is a surge protection component designed for power supply protection, LED driver protection, and industrial power reliability. When designing power circuits or LED drivers, engineers face one key challenge: preventing sudden transient voltage spikes from damaging sensitive components. The Kingtronics XKT Series provides fast, repeatable surge suppression that helps maintain long-term system stability.

Reliable Surge Protection Across 18V–1800V
Kingtronics XKT Metal Oxide Varistor surge protection for power and LED driver designs

The XKT MOV Series is engineered for industrial-grade surge protection, covering a wide operating voltage range from 18 V up to 1800 V. With fast clamping response and high energy absorption capability, the device helps protect AC/DC power supplies, LED lighting modules, industrial controllers, and consumer electronics from transient surges or lightning-induced spikes.

Key advantages of Kingtronics XKT Series:

• Wide operating voltage range supports multiple circuit designs and ratings
• High surge capability (series options up to 20 A peak rating, per datasheet test conditions)
• Designed to absorb high-energy transients (up to hundreds of joules depending on series size)
• Full compliance with RoHS and REACH environmental requirements
• Protection for industrial control modules, telecom DC rails, and power converters

Compared with well-known brands such as EPCOS (TDK), the Kingtronics XKT Series targets equivalent functional performance while offering a more competitive cost position for sourcing and design-in.

How a Metal Oxide Varistor (MOV) Protects Your Power Circuit
Transient surge suppression and voltage clamping behavior

A Metal Oxide Varistor (MOV) is a voltage-dependent resistor. Under normal operating voltage, the MOV remains in a high-impedance state and does not significantly affect the circuit. During a surge event, the MOV switches to a low-impedance path and clamps the excessive voltage, diverting surge current away from the sensitive load. This fast response helps prevent damage to downstream ICs, drivers, or control modules.

In typical usage, the Kingtronics XKT MOV is placed across the input line of a power circuit. When a spike appears on the line, the varistor reacts within microseconds to suppress dangerous peaks and stabilize the line voltage.

Image alt text: Kingtronics XKT Metal Oxide Varistor (MOV) showing disc package, used as a transient surge suppression component for AC and DC power lines.

Typical Application Areas for the XKT MOV Series
Power supply protection / LED driver surge protection / industrial electronics

• Power supply surge suppression and AC line transient protection
• LED lighting and LED driver surge protection
• Industrial automation equipment and control modules
• Consumer electronics and power adapters
• Communication and telecom systems (DC rail protection)

XKT Series Demonstration Video
Reliable surge protection across 18 V–1800 V applications

The following video introduces the Kingtronics XKT Series and shows how this MOV-based surge suppression approach helps protect real-world power systems.

Explore the Kingtronics XKT Metal Oxide Varistor Series
Product information, datasheet, RFQ / sample request

Download the Kingtronics Varistor Catalog
Full XKT family overview and detailed electrical ratings

Kingtronics XKT / RKT / WKT / NKT Varistor Catalog (PDF)

View the complete Kingtronics varistor product range, including XKT Series Metal Oxide Varistors, package dimensions, voltage range, surge energy capability, and ordering information.

Open Full Catalog (PDF)

The catalog helps sourcing teams compare part numbers and check available voltage ratings across 18 V to 1800 V application requirements.

Technical Reference for Engineering Teams
Operating range, energy rating, environmental compliance

• Operating temperature range: –40 °C to +105 °C
• Available disc sizes / series: 5D, 7D, 10D, 14D, 20D
• Energy absorption capability: approximately 0.4 J up to 606 J (10/1000 µs waveform, depending on series size)
• High peak surge current performance (up to 20 A series rating class)
• RoHS and REACH compliant
• AC and DC working voltages from 18 V class up to 1800 V class across the full Kingtronics XKT range

Kingtronics® XKT Metal Oxide Varistor Series — surge protection for power supply, LED driver, telecom and industrial control applications.
Protect your design, improve long-term reliability, and maintain stable operation under real-world transient conditions with a qualified surge suppression component.