Welding Transformers

Welding transformer - a device that converts AC line voltage to AC voltage for welding (usually lowers the AC voltage to a value less than 141). The device is single-station welding transformer with movable coils is shown in the figure below.

Regulation of current in a welding transformer, by means of the mobile coil.

current control in the welding transformer with movable coils

Commercially produced welding transformers for manual arc welding and welding transformers for automatic submerged arc welding.

Types of welding transformers

• welding transformers amplitude control with a normal magnetic scattering - with a throttle with an air gap or choke saturation;
• welding transformers regulate the amplitude with increasing magnetic scattering - from moving or spaced windings, with the reactive coil, with a movable magnetic or magnetized shunt with a capacitor or a pulse stabilizer;
• thyristor welding transformers (phase regulation) - the impulse to stabilize or recharge.

Welding transformers amplitude regulation
In the welding transformer amplitude control mode is set change in resistance welding transformer, or change the open circuit voltage without distortion of the sinusoidal alternating current.

A transformer with a normal reactive scattering and single coil (choke)

A transformer with a larger scattering and moving coil

Thyristor welding transformers
Thyristor welding transformer consists of a power transformer and thyristor phase regulator, housed in a primary or secondary circuit with two back-to-parallel connected thyristors and control system. Principle of phase control is to convert the current to alternating sinusoidal pulse, the duration and amplitude are determined by the phase (angle) thyristors phase regulator.

If there are current-free phase regulation pause, which leads to a decrease in the stability of the arc. To increase the stability of the arc using a pulsed current stabilization or feed, for example, from the auxiliary transformer.

External incident response is formed by a transformer with a larger magnetic scattering or by negative feedback current. The greater the angle of thyristors, the less current and steeper slope of the external characteristics of the incident.

The advantages of welding transformers

• low cost of manufacture (welding transformer is about 2-4 times cheaper than welding rectifier, and is 6-10 times cheaper than welding machine of similar capacity);
• high efficiency (typically 70-90%);
• relatively low power consumption;
• ease of maintenance and repair.

The disadvantages of welding transformers

• for high quality welding usually requires special electrodes for alternating current, which have higher stabilizing properties;
• low stability of the arc (in the absence of built-in stabilizer arc);
• in simple transformers - dependence on mains voltage fluctuations.

See also:
manual arc welding

Welding Equipment:
Welding Transformers
Welder
Welding Rectifiers
Welding Inverter
Welding Machines