The Kemppi RA 450A is a transformer MIG/MAG power source with a welding current of 450 A at a 50% duty cycle and 310 A at a 100% duty cycle. Supply 400 V, liquid cooling, weight 220 kg. You set the voltage with a step switch and control the wire feed steplessly.
What this machine is for
This is a power source for semi automatic welding under active and inert gases, on carbon steel and on high alloy steels. The 310 A at a 100% duty cycle means continuous work, also across several shifts, and the 450 A at a 50% duty cycle gives a reserve for thick plate and deep penetration. The source record speaks of continuous welding at a current above 300 A, that is the pace at which larger diameter wires and a high feed speed run.
A three phase supply holds the arc with high energy, which makes it easier to carry the pool on structural steel and gives welds with repeatable strength values. Such a machine is taken by a works making heavy steel structures, a fabrication shop, a shipyard, a plant repairing farm machinery and construction equipment, and firms in civil and bridge engineering.
The transformer design stands up to dust, damp and temperature swings better than a modern inverter. There is no extensive control electronics here, so service comes down to parts you can measure and replace, and the arc characteristic is hard and predictable. This is the choice of a workshop that goes for a simple build instead of a digital controller.
Liquid cooling takes heat from the torch and from the power parts, so you lay a weld at a high current without overheating the torch and without damage to the insulation of the cables. In continuous work this is the condition for the consumable torch parts to last a whole shift.
Typical uses are heavy industrial production and fabrication shops, welding of thick parts of bridge and building structures, repairs of farm machinery and heavy equipment, work in shipyards and in power generation. In short: everywhere the machine has to offer the simplicity and toughness of a transformer and not extensive digital functions.
Features and equipment
- Transformer build. A proven technology with no digital controller, easier to service and less sensitive to conditions in the hall.
- Stepped welding voltage control. Each step of the switch matches a set characteristic, so the setting for a given material thickness is repeatable and will not change by accident during work.
- Stepless wire feed control. The feed potentiometer lets you correct during welding, when the gap or the position changes and the amount of wire fed has to match the power of the arc.
- Integrated liquid cooling. The circuit carries heat away from the torch and the power parts, so the torch does not overheat at high currents.
- A wheeled trolley. You push the machine across the shop floor, also over uneven ground, without a forklift.
- Space for a gas cylinder and equipment. You keep the station in one place and the cables do not lie loose in the walkway.
- Weight 220 kg. The copper windings of the transformer give a large thermal inertia and a stable base for the station.
- A hard arc characteristic. The arc is predictable and little affected by dirty material, so you strike on scrap and on rusty surfaces without fiddling with the settings.
- A simple power circuit. With no digital controller, fault finding is shorter and there are fewer parts to order for a repair.
Technical data
| Brand | Kemppi |
|---|---|
| Power source type | transformer |
| Process | MIG/MAG, manual welding |
| Supply voltage | 400 V |
| Welding current at a 50% duty cycle | 450 A |
| Welding current at a 100% duty cycle | 310 A |
| Cooling type | liquid |
| Voltage control | stepped |
| Wire feed control | stepless |
| Machine weight | 220 kg |
| Dimensions | 120 x 80 x 150 cm |
What to watch out for
The supply is 400 V, three phase, so you need a three phase socket and a fuse matched to the draw at the top settings. The weight of 220 kg and the dimensions of 120 x 80 x 150 cm mean you need a forklift to unload it and a permanent place in the hall with a level floor. Liquid cooling needs attention: before you start, check the fluid level, the work of the pump, the flow and the tightness of the torch quick couplings.
Voltage control is stepped, you cannot set a value between the steps, so you match the parameters with the wire feed speed. There is no pulse and no synergic programs here, the choice of settings stays with the welder, and it is worth writing down the settings for repeat joints at the station. This power source is not meant for aluminium, because without pulse and without material programs it is hard to run soft wire.
The record does not list a welding torch, an earth cable or a wire feeder, so confirm the equipment before you buy and choose a torch rated above the working current. It is also worth settling which coolant is in the circuit and when it was changed, because the state of the pump depends on it.
How we sell used machines
This unit was checked in our service workshop in Krotoszyn with measurements to PN-EN 60974-4 and a load test. The price includes the first year of the basic service package: an inspection with cleaning of the machine and a validation measurement. Further years can be added. We ship across the European Union, collection in person by appointment.
