Solid State HF Welder
Vacuum Tube HF Welder
DC Drives (Analog Type)
Distribution panel (PCC-MCC-Braker)
Custom Build PLC Controlled Panels
DC Drive (Digital type)
AC Drive (Variable frequency drive)
Vacuum Tube HF Welder

Sai Automation welders are most suitable for welding of pipe and tube from 8mm-300mm. For  small diameter  use induction welder and contact welders are suitable for large diameters.

A Sai Automation induction welder at full output achieves 2%-3% energy saving, over a welder with fixed output transformer.

Sai Automation welder are designed for continuous operation to perform under most hostile environment.

Each welder consists of a Hartley or colpitts type oscillator circuit, with grounded cathode design to reduce voltage stresses on oscillator components.
Each welder components like power supply cubicle, oscillator cubicle and heat exchanger has been designed and built to rigorous standards to ensure reliability and product life. Every welders are thoroughly tested at dummy load prior to dispatch, ensuring minimum erection and commissioning time.

Easy Accessibility

The power supply and Oscillator cubicle are housed in separate cabinets. Therefore the power supply cubicle can be located away from welding area and oscillator cubicle should be located as close as possible welding area. Both cubicles dust and vermin proof and contain internal air/water heat exchanger to maintained all components cooling at required temperature.

The closed circuit distilled water cooling circuit is made of copper tubes with crome plated and best quality rubber hose pipes to prevent any galvanic corrosion within the equipment.

Standard Protections

  • Magnetic short circuit (provided in the main supply MCCB).
  • Instantaneous electronic over current trip.
  • Instantaneous DC magnetic over load relay.
  • Ambient temperature thermostat.
  • Magnetic float type water flow switch.
  • Thyristor over temperature thermostat.
  • Metal oxide varistors in the incoming lines to protect thyristors from  high voltage transient in the main supply.
  • “Spark Gap” to protect oscillator valve and other components.
  • Earth droppers.
  • Electromechanical door inter lock in high voltage compartment.
  • Input water over temperature thermostat.
  • Oscillator valve output temperature thermostat.
  • Oscillator valve seal over heat.

Major Components Of Hf Welder

  • Compact and separately sealed enclosures for power supply and oscillator cubicle.
  • Moulded case circuit breaker with short circuit breaker.
  • Triple pole power contactor of suitable rating for disconnecting the mains supply.
  • Closed loop Thyristor (SCR) power control system. By controlling the phase angle of  the thyristors, the welder output can be adjusted from zero to maximum step lessly and at the same time welder output is stabilized to +/-1% for an input voltage variation of 10%.
  • Programmable logic control (PLC) used for complete control circuit (optional).
  • Alphanumeric digital display for fault diagnostic information and on line welder Parameters (optional).
  • Meters is mounted on the door of the power supply cubical and operating control desk.
  • Oil cooled high tension plate transformer. The Transformer has high impedance so as to limit the short circuit current to a max. of 10xI rated. It steps up the thyristor controlled main AC voltage into high voltage AC to feed the high voltage rectifier.
  • Low ripple LC Filter. It is incorporated so as to bring down the ripple content in high voltage DC supply.
  • DC High voltage rectifier with silicon diodes. It rectifies the high voltage AC power from the H.T. transformer to the DC power required for the oscillator.
  • Magnetic overload relay.
  • Plate & grid choke.
  • Water cooled metal-ceramic oscillator valve.
  • Water cooled ceramic tank capacitor.
  • Grid bias disc capacitors.
  • Water cooled grid bias resistance assembly.
  • Oscillator valve filament voltage regulator. A single phase closed loop thyristor control voltage regulator is provided to regulate oscillator valve filament supply.  The filament supply is stabilized to +/- 2% for an input supply variations of +/-10%.  Filament voltage is gradually set by a built in ramp circuit.
  • HF Transformer.
  • Water flow switches
  • strainless steel plate type heat exchanger  with Non ferrous pump and PVC Tank all assembled on a steel frame and interconnect with copper pipe line for distilled water circuit.
Welder 3 Welder 4  
Oscillator Cubicle (Colpitt Type) Power Supply Cubicle  


Oscillator Cubicle
Oscillator Cubicle (Hartley Type)
Heat Exchanger Assembly
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