GTO Protection Capacitors


Introduction

NCL snubber capacitors are designed to meet the requirements of the traction industry and for static drive applications. They are built to extremely high standards, offering enhanced properties over other similar looking designs. Wound with a combination of metallised polypropylene film and extended aluminium foil electrodes which, in conjunction with a stable, biodegradable liquid impregnant ensures extremely long life and reliable self-healing capabilities. The loss angle (tandf) is extremely low (<0.0003 at 1kHz) and the aluminium foil electrodes provide excellent thermal characteristics.

Application

NCL snubber capacitors are designed for the severe duty of gate turn-off thyristors (GTOs). They are also for tuning applications in the medium frequency range.
Technology

The advanced polypropylene dielectric system of these capacitors has been specially developed for high peak current and surge voltage applications.

Encapsulated in fire-resistant epoxy resin, the extremely strong robust mechanical design is suitable for the rigours of traction duty, especially vibration conditions and high ambient temperatures. M8x8 mm axial connections are provided, which are securely bonded to the foil electrodes.

The range below should not be considered as definitive. For example:- NCL is able to manufacture special high temperature versions which are capable of operation up to 120°C. For any models not shown within these ranges, please contact us for further details.

Characteristics

The following parameters are applicable to the range of capacitors which appear on the following pages. As mentioned above, should a particular combination of capacitance value or voltage not be available or should there be a dimensional constraint, please contact us for a design suited to your particular needs.

Capacitance value: 0.25¥ìF to 8¥ìF
Tolerance: ± 5%
Voltage rating (Udc): 900V to 3700V
Peak repetitive voltage (UN): 1400V to 5500V
Peak non-repetitive voltage (Us): 1800V to 7200V
Maximum surge current: 700A to 8200A
Loss angle (tandf): <0.0003 at 1 kHz
Insulation resistance: >10,000 sec
Current rating: Up to 120 A rms, depending on capacitance, voltage rating and thermal constraints
Operating temperature (qamb): -40 to +70°C
Storage temperature: -40 to +85°C
Connections/tightening torque: M6 x 6 mm internal thread brass connection - 3 Nm
M8 x 8 mm internal thread brass connection - 6 Nm
International standard: In accordance with IEC 61071 & IEC 61881

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