Production engineering characteristics
- Increased electric strength of insulation
- Absence of enameled wire overlaps in windings
- Absence of humming under load
- Absence of barrel shape
- Dimensions variability
- Enhanced technical control
- Easy connection
Increased electrical strength of insulation
Winding electrical strength increase is achieved by interlayer insulation (between each layer or after several layers of winding). Varnished cloth, polyethylene terephthalate film (PET), PTFE tape are used for such insulation depending on required electrical strength and heat resistance.
To avoid breakdown between primary and secondary windings reinforced insulation is used. The inspected core is insulated according to transformer specification with:
- polyethylene terephthalate film not less than 35 µm for core and 20 µm for interlayer insulation and final product insulation;
- PTFE tape;
- varnished cloth (LKM, LKSM, LSM);
- electroinsulating material vacuum impregnation.
If necessary the core is insulated with electrocardboard of 25-50 µm.
These stages prevent electrical breakdown between core, primary and secondary windings.
Absence of enameled wire overlaps in windings
Transformer windings are made only of high-quality wire PET-155, PETD-200 for heat temperature up to 155 (200)°Ñ during continuous operation for many years. Available equipment permits to lay wire avoiding overlaps and also provides maximum possible tight winding for a given section.
Wires are laid evenly around the magnetic circuit or strictly by sections, that positively affects the magnetic field around the transformer.
Absence of humming under load
To avoid transformer humming under load the magnetic core of cold-rolled grain-oriented electrical steel (3408 – 3413 grades) is applied. Steel quality and grade conformance inspections are made on special equipment (including the ITTS-20 unit). Winding of magnetic circuit is performed mechanically with a rigid control of output dimensions and minimum air gap between the coils. Cores are burned in special furnaces. The burning temperature range is kept according to the engineering process.
Due to these procedures the repetition of transformers mass-dimensions and electrical parameters (minimum idle running current, constant output voltage, low power losses) is provided.
The core impregnation with varnishes ML-92, FL-98, KO815 is performed for Hi-End equipment transformers.
Absence of barrel-shape
Key points to avoid the barrel shape of our transformers are:
- correct calculations and design of the finished transformer geometric dimensions;
- magnetic circuit ends rounding-off;
- maximum accurate selection of permissible winding wire tension and special way of its laying.
As a result transformer reliability is increased and barrel shape is avoided while transformer dimensions are reduced.
The core selection for transformer winding is made for a specific customer product due to the maximum permissible dimensions. The customer is offered a choice between several options and sizes of finished transformers, the price for each type is calculated.
Enhanced technical control
All transformers are tested after winding:
- Load test is made by special unit during certain time depending on transformer power and customer additional requirements;
- Electrical parameters are checked (Ii.r., Uout.);
- Dimensions and mass-dimensions are measured.
Transformer leads are made by windings wires for easy connection (it reduces slightly the price, but complicates the connection) or coloured flexible wires. Leads are marked according to specifications and special plugs are installed..
Transformer windings are equally spaced across the core diameter, which in turn allows You to distribute load and improve transformer temperature range.
Transformer can be epoxy potted or completed with fixture on customer.
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