Solid State high frequency induction welder

Solid State high frequency induction welder is called as Solid State High Frequency Induction Welder because it use solid state devices.

Vacuum tube high frequency welding pipe equipment has been used by the steel tube industry from a long time. The design and working was up to the peak and every one familiar with its operation and servicing. The equipment quality and the operation stability have been accepted by the general welding pipe enterprises. Due to the vacuum tube involved in the circuit there were high losses in the equipment potential that is why there was a need for better equipment in the industry. When transistors, IGBT and MOSFET were developed and upgraded day by day, eventually solid state HF welders came into existence. Initially there were some flaws due to limitations of the components. Now with availability of very high quality electronic components and advanced technology , the third generation solid state welder is very much stable, rugged and widely accepted by the industry due to its numerous advantages over vacuum tube welder.

The main advantage is its high efficiency with low losses thus save lot of energy cost. Along with the promoted application of solid state welded pipe equipment, its strong advantage for highly effective energy conservation opened a new path for the intense welded pipe profession competition. The third generation solid state high frequency power supply has many fine performances.

In context to the vacuum tube welder, the Solid-state welder gets its name from the way how the path, that electrical signals take through solid pieces of semi-conductor material. Prior to the use of solid-state devices, such as the common transistor, diodes, resistances and allow electricity to passed through the various elements inside of a heated tube/pipe. Solid-state devices, such as a transistor, use conductors to control the flow of signals through a circuit.

§  In a transistor amplifier, a small change on the input signal’s amplitude is immediately reflected in larger amplitude in the output within a transistor.

§  In a vacuum tube amplifier, after the tube warms up, a signal is applied to the “grid” of a tube and the resultant output of the same frequency is at a much higher amplitude.

In the sandwich-like construction of a transistor, the emitter, base, and collector do a similar task at much lower DC voltages, with no “warm-up” time! In digital circuits, an integrated circuit chip is nothing more than that of a collection of transistors and wires that hook them together.
Solid state devices called mosfets have replaced vacuum tubes, used to transform direct current (DC) to alternating current (AC). Cool-running light-emitting diodes (LEDs), another solid-state device used for indicators on the front panel of your computer and monitor, have replaced the earlier incandescent bulbs.


The whole solid state high frequency induction welder has its four main components that are as follows:

    1. Rectifier Cabinet
    2. Inverter Cabinet
    3. Distilled water cooling unit
    4. Operator control Desk
      1. Rectifier Cabinet: – The rectifier cabinet converts the incoming AC power supply into variable DC power supply. The DC power is filtered by installing reactors and filter capacitors. Input Line reactor is installed to limit the current and sudden surges. Many types of protections are incorporated in the circuit for safety of the equipment and components Siemens PLC is used for control circuit logic and interfaced with a digital touch screen on operator control desk. The cabinet is made of high quality CRC Sheet duly fabricated as per dust proof design. The paint is high quality powder coated.
      2. Inverter Cabinet: – High power mosfet modules are used in inverter cabinet. The Mosfet’s are German IXYS Make with fast recovery diode mounted on water cooled copper plate. The modules are designed such as one module can be replaced easily. The inverter cabinet is made of high quality CRC Sheet duly fabricated as per dust proof design. The paint is high quality powder coated. The high power sandwich type capacitors are installed on copper plate, water cooled by closed loop distilled water circulation. The angle lead passes the power to the pipe through the work coil.
      3. Distilled water cooling unit: – The Distilled water cooling unit in solid state high frequency induction welder uses distilled water for cooling the whole unit and the same water supply is circulated through the whole unit. The pump used in high quality industrial grade nonferrous pump. The water is stored in a tank and pumped through a stainless steel plate type heat exchanger into the solid state high frequency induction welder. The plates of heat exchanger are made of stainless steel grade SS316. The whole unit is mounted on structural steel fabricated unit. The heat exchanger unit is the latest technology and very highly efficient. Distilled water flows in alternated plates and in other plate raw soft water is circulated. The heat of distilled water is transferred to the raw water. Raw water is cooled by induced draft type cooling tower.
      4. Control Desk: – The Control Desk provides various interface to the operator to control the power of Solid State high frequency induction welder. The operation push button and power control pots are installed on the desk. Digital LCD Screen is provided to observe the running parameters as well as fault/ healthy state of Solid State high frequency induction welder. Push button controls for speed control of tube mill is also installed on the desk. Indicating lights and meters for parameters are also installed on desk for observation while running the tube mill. Emergency push button is also provided with interlocks as required.


Welder Model
Output Power
Electricity Efficiency
60 KW
450 ~ 500 kHz
≥  85 %
100 KW
400 ~ 450 kHz
≥  85 %
150 KW
350 ~ 400 kHz
≥  85 %
200 KW
300 ~ 350 kHz
≥  85 %
250 KW
300 ~ 350 kHz
≥  85 %
300 KW
300 ~ 350 kHz
≥  85 %
400 KW
200 ~ 300 kHz
≥  85 %
500 KW
200 ~ 300 kHz
≥  85 %
600 KW
200 ~ 300 kHz
≥  85 %
700 KW
150 ~ 250 kHz
≥  85 %
800 KW
150 ~ 250 kHz
≥  85 %

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