Inverter Welding - TRE.CI SINCE 1977


Matteo Marzetti +


Albertin Stefano +

Inverter Welding

While the welding made by means of single-phase fed AC transformers where the welding power is adjusted through SCR and choked by obtaining continuous passages from "zero" and cold intervals making the welding "core" not homogeneous and with oxidised parts, welding through inverter technology allows rectifying the current and filtering it by AC IGBT with higher frequency compared with the electric system (generally of 1000 Hz).

This last will feed a transformer, made just for this purpose, for high frequencies, on which there will be, as secondary item, a diode bridge enabling the delivery of a direct welding current.

The first evinced advantage is that, welding with direct current, there aren't any "cold" interruption and passages from "zero" enabling to obtain a homogeneous welding "core” free from oxidised parts; therefore, it's possible to weld light alloys.

In addition, the high frequency allows adjustments and, above all, quick and accurate feedbacks (millisecond by millisecond).
Such a quick feedback enables to weld at lower pressures obtaining fewer deformations of the part, a longer life of electrodes and the smallest welding heads.

Moreover, a lower power consumption and the three-phase feeding that prevents from the shift of the feeding current obtaining a cosφ of almost 1.

All our welding heads, including the PAT 1 (micro), can be delivered with an inverter system, thanks to the wide range of available transformers and generators.

With forced air cooling:
150 Amp / 300 Amp/ 600 Amp

With water cooling (consumption: 4l/minute)
300 Amp / 600 Amp / 1200 Amp
  • Power inverter using IGBT technology for medium–frequency output, programmable via terminal or via remote field bus.
  • Software availability to drive DC transformers (Square wave output) or to drive AC transformers (Sine wave current output)
  • Frequency set by the user from 1 KHz to 5 KHz in case of DC Transformers or 50 to 1000 Hz in case of AC transformers.
  • User selectable primary or secondary current measurement.

Six different modes of current regulation are available:



    • Duty fixed percentage D‰
    • Duty percentage with primary voltage compensation, V‰
    • Constant Current IK
    • Constant Power PK
    • Constant Energy EK
    • Adaptive AD

  • Welding current set by external voltage reference 0-10V
  • Gain adjustable current regulation loop.
  • Cycle management of spot welding machines or rollers welding machines set by user.
  • Time management in periods or in milliseconds.
  • Electrical insulation of input and output sections.
  • Setup and execution of 64 programs, called by external input, internal, sequential or associated with the start cycle IC1 or IC2.
  • Point to point serial communication line RS232, used to connect a printer or a personal computer or a network serial communication line RS485.
  • Availability of expansion of communication: Profibus – DeviceNet – CANopen - Modbus/RTU - Profinet/IO - EtherNet/IP – EtherCAT - Modbus/TCP.
  • Start cycle with dual push buttons (dual input) or pedals (single input).
  • Monitoring (Quality Control) of the limits of the welding current in spot-weld and in rolls weld mode.
  • Programmable function of continuous current increment to compensate electrodes wears under variable curve up to four pairs of electrodes (four transformers).
  • Welds counter with alarm and lock function.
  • Four solenoid valves flexibly associated to pre-squeeze and squeeze within programs.
  • Proportional valve driving circuit galvanic insulated.
  • Proportional valve full scale setting (99%) from 5 to 10V.
  • Forging solenoid-valve output.
  • Pre-stroke solenoid -valve.
  • Possible association of pressure in pre-squeeze, squeeze, preheat, welding and forging, through the proportional valve (pressure cycle).
  • Self-calibration of 4 transformer or welding systems.
  • Four language setting, additional languages on request.
  • Dedicated signals management by PLC.
  • IGBT power unit with water or air cooling, through integrated water control solenoid valve or fans.
  • Possibility of external 24V power supply in case of lack of power line.
  • Temperature monitoring of heat sink.
  • External temperature monitoring (transformer diode or coils).
  • Automatic checking and errors reports on Rogowski coil insulated or in short.
  • Check with any reporting / management start welding pliers not closed.
  • Graphs trends of weld parameter on the terminal panel.
  • Automatic duplication of the welding program in multiple programs

- Models: CSI-300A - CSI-600A - CSI -1200A - CSI-2400A / CSI-151A - CSI-301A - CSI-601A.

(D C - A C)
(D C - A C)
Cooling System
Acqua - flusso 4 l/min, Temp. da 20°C a 40°C
Water - flowrate 4 l/min, Temp. from 20°C to 40°C
Wasser - Durchfluß 4 l/min,Temp. von 20°C bis 40°C
Aria Forzata
Forced Air
Forcierte Luft
Input Voltage
Versorgung Spannung
Threephases | 400 - 440 Vac ± 15% 50/60 Hz
Tensione d’uscita
Output Voltage

           onda quadra
500 V | square wave
           rechteckige Welle

Potenza @ 20% Duty Cycle
Power @ 20% Duty Cycle
Listung bei 20% E.D.
300 KVA
600 KVA
1200 KVA
75 KVA
150 KVA
300 KVA
Corrente d’uscita
Output current
Ausgang Strom
600 A
1200 A (DC)
450 A (AC)
2400 A (DC)
900 A (AC)
150 A
300 A
600 A
Frequenza d’uscita
Output Frequency
Ausgang Frequenz
( fino a ) ( fino a )
[ DC 1 KHz up to 5 KHz ]
( Bis zu )
( fino a )
[ AC 20 Hz up to 1000 Hz ]
( Bis zu )
Control Modes
Duty‰ - Tensione Costante V‰ - Corrente Costante - Potenza Costante - Energia Costante - dattativo
Duty‰ - Constant Voltage V‰ - Constant Current - Constant Power - Constant Energy - Adaptive
Duty‰ - Konstant Spannung V‰ - Konstant Strom - Konstant Leistung - Konstant Energie - Anpassungsfähig
Ingressi di misura
Measures inlets
Corrente Primaria - Corrente Secondaria - Tensione Elettrodi
Primary Current - Secondary Current - Electrodes Voltage
Primär Strom - Sekundär Strom - Elektroden Spannung
Temperatura Operativa 
Operating Temperature
da 0°C a 50°C
from 0°C to 50°C
von 0°C bis 50°C
Umidità Operativa
Operating Humidity
fino a 90% C, non condensata
up to 90% C, non-condensing
bis 90% C, keine-Kondens
Profibus - DeviceNet - CANopen - Modbus/RTU - Profinet/IO - EtherNet/IP - EtherCAT - Modbus/TCP.
Dimensioni ( L x h x P )
Dimensions ( W x h x D )
Abmessungen ( L x h x T )
415 x 305 x 270 mm
505 x 324 x 322 mm
403 x 230 x 267 mm
415 x 305 x 370 mm
23 Kg
45 Kg
17 Kg
30 Kg




T25/5 500 V. 5 KHz 25 KVA/50% 11,5 V 1 KA/50% 16 KA
T250/1 500 V. 1 KHz 180 KVA/50% 10,2/11,8/13,2/14,2 25 KA/50% 180 KA
T130/1 500 V. 1 KHz 130 KVA/50% 7/8/9/10 V. 13 KA/50% 180 KA
T100/1 500 V. 1 KHz 100 KVA/50% 9,1/10,2/11,7/13,1 11 KA/50% 180 KA
T101/1 500 V. 1 KHz 100 KVA/50% 9,1 V. 13,5 KA/50% 120 KA
T40/1 500 V. 1 KHz 40 KVA/50% 4,5/5,8/6,9/8,9 6,5 KA/50% 60 KA

Direct contact

Headquarter Tre.Ci

Via Pasubio, 57 int.2 Paderno Dugnano (MI)

Working hours

09.00 - 18.00

Tre.Ci since 1977

TRE.CI is a small company founded in 1977 and since then millions of spots made with welding machines that carry this name were made.

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