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Welding Transformers

A welding transformer is a step down transformer that reduces the voltage from the starting place voltage to a lesser voltage that is right for welding usually between 15 and 45 volts. The secondary current is fairly high from 200 to 600 amps would be characteristic, but it could be much upper. The secondary may have more than a few taps for adjusting the secondary voltage to control the welding current. The taps are classically linked to a more than a few high-current plug receptacles or to a high-current switch.

For welding transformer with direct current (DC) a rectifier is linked to the secondary of the welding transformer. There may also be a filter choke (inductor) to soft the DC current. The whole transformer and rectifier assembly may be called a welder or transformer, but "welding power supply" would be more appropriate term.

How it works:

The main is a 100 turn coil that is linked to the mains 110V supply. The secondary process is a 9 turn coil made of 9 x 9mm iron. Attached to each finish of the coil (their positions shown in Figure 1) are 2" nails. When the nail ends are brought jointly (by pressing the higher onto the lesser) to complete the circuit in the secondary process, the current is enough [+ how much?] to heat up and fuse the nail tips.

The welding transformer core cross section is 6 x 6cm made from covered iron strips, giving a total dimension of 24cm wide and 36cm high.

Figure 1. The welding transformer

Setting it up:

The nails can be pressed jointly by hand, but you may want to supply a glove to protection the sparks. Make sure that the top piece of the iron core of the welding transformer is in place before plugging in the 110V primary. Without nails there is not enough inductance in the primary and the circuit breakers will trip.


Maintenance, Economical, Elegant & Excellent Welding characteristics.

Modern, Compact & Tropicalised Design, Reliable, Stepless Current Control, Efficient, Negligible.


MODELS BW - 300 BW-400 BW-500 BW-600
Input Voltage  V 380 / 415 380 / 415 380 / 415 380 / 415
Phase 2  L i n e s   o f   3  P h a s e 
Frequency Hz 50 50 50 50
Rating Continuous KVA 16 22 28 34
60% duty Cycle KVA 24 32 40 48
Open Circuit Voltage V 80 80 80 80
Operating Arc Voltage V 22 - 32 22 - 36 23-40 23-44
Welding Current Range Min / Max A 40-300 50-400 60-500 70-600
Maximum Hand Welding Current
at 60% Duty Cycle
A 300 400 500 600
Maximum Continuous Automatic Welding Current at 100% Duty Cycle A   200 275 350 425
Welding Electrode Size Ø mm 2-6.3 2-6.3 2.5-6.3 2.5-6.3
Switch-Fuse Recommended A 60 80 100 125
Capacitor for power factor correction KVAr 7 8 10 12
Type of cooling - FAN FAN FAN FAN
Class of Insulation Class H H H H
Approx. Dimension : Height cm 75 75 75 75
Length cm 75 80 90 90
Width cm 65 65 65 65
Approx. Weight Kg. 100 110 130 150

Application :- General Purpose Fabrication, Medium & Heavy Structures, Machine Building,Maintenance work, Adaptable for TIG welding of Aluminium & Magnesium

Suitable :- For Engineering / Fabrication - Works, Steelplants  & Ship Yards etc.












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