Solid-state HF welder

A solid-state HF welder has been installed at ZPT JSV Bulgaria

The EMMEDI & Annealing Division of SAET GROUP has installed an advanced MOSWELD solid-state HF Welder 200kW output power at ZPT JSC Bulgaria.

ZPT is a factory located in Straldzha, manufacturing carbon steel tubes. The new MOSWELD is installed on a tube mill producing tubes from 60mm to 150mm and WT up to 4mm.

The solid-state welder generation MOSWELD, based on a MOSFET-type inverter is able to work up to 450kHz. As typical working frequencies in tube welding process are in the range 300– 45kHz, MOSFETS are one of the most cost-effective choices for this application, the company claims.

A system control board communicates with the inverter through optical fibres that are provided on the unit. The inverter is a current fed type and the output oscillating circuit is directly connected to the inverter.

The company says MOSWELD has the following advantages: high efficiency; modular design; easy maintenance; it is short circuits proof; it has much lower voltages inside the cabinets compared with oscillator tube technology; power components are not subject to obsolescence; it uses the same coils as the classic oscillator tube welder; and it offers long-term reliability.

The modular structure and a complete diagnosis system allow quick and easy maintenance in order to reduce production stops. A special digital control system has been developed for an optimum phase locking (and then for an efficiency increasing) with the possibility to follow the change of frequency due to load variation in any working condition.

PUBLISHED: 12 Dec 09