150 kVA Residential Electrical Transformer-24.94/0.208 kV | USA 2024

Premium quality, long-lasting performance, and intelligent design – Three-Phase Pad-Mounted Transformer, safeguarding the future of power systems!

01 General

1.1 Project Description

SCOTECH recently exported a top-of-the-line 150KVA residential electrical transformer to Jamaica. The rated power of the transformer is 150 kVA with ONAN cooling. The primary voltage of the residential electrical transformer is 24.94GrdY/14.4kV, while the secondary voltage is 0.208GrdY/0.12kV with two voltages in the LV side. they formed a vector group of YNyn0. Using YNyn0 connection and three-phase five-column structure, high voltage quality, neutral point does not drift, box does not heat, low noise, good lightning protection performance. The high-voltage side of the pad-mounted transformer connects to the medium-voltage distribution network. After passing through high-voltage load switches and fuses, the current flows into the transformer windings, where voltage conversion occurs. The low-voltage side then supplies power to the load through terminal connections, supporting three-phase, four-wire power systems.

1.2 Technical Specification

150 KVA pad mounted transformer specification and data sheet

1.3 Drawings

150 KVA residential electrical transformer diagram drawing and size.

02 Manufacturing

2.1 Core

Core action – component of the magnetic circuit In order to reduce hysteresis and eddy current loss in the iron core, the iron core is stacked with 0.35 ~ 0.5mm thick hot rolled or cold rolled silicon steel sheets, and the pieces are coated with 0.01 ~ 0.013mm thick paint film to avoid short circuit between the pieces. The use of staggered core stacking (large transformers use diagonal steel sheets) can reduce the air gap and reduce the excitation current.

2.2 Winding

Winding action – part of a circuit It is wrapped with paper, yarn or lacquer insulated flat wire or original wire, which can induce potential and realize electromechanical energy conversion through current. The winding adopts concentric structure. The so-called concentric winding is that on any cross section of the core column, the winding is set on the outside of the core column with the same cylindrical line. There must be a certain insulation gap and heat dissipation channel (oil passage) between the high and low voltage windings, as well as between the low voltage windings and the core column, and separated by an insulating cardboard tube. The size of the insulation distance depends on the voltage level of the winding and the gap required for the heat dissipation channel. When the low-voltage winding is placed inside close to the core column, the required insulation distance between it and the core column is relatively small, so the size of the winding can be reduced, and the overall size of the transformer is also reduced.

2.3 Tank

The function of the oil tank: the iron core and the winding constitute the body of the transformer, which is placed in the oil tank equipped with the transformer, and the transformer oil is both the insulating medium and the cooling medium. This kind of transformer produced by our company adopts box type tank (hanging core type tank). The upper box cover of the transformer can be opened, and its total weight after oil filling is not too heavy compared with that of a large transformer; Therefore, when the transformer body needs to be repaired, the entire transformer with oil can be transported to the place with lifting equipment, the box cover is opened, the body is lifted out, and the maintenance is carried out. The wall of the tank is bent and formed with steel plate, the section is mostly oval or rectangular, and the sealing rubber pad is placed between the edge of the box and the cover, and then the fixing bolt is used to seal it. The edge of the tank is arranged on the top of the tank, and the cover is connected with the use bolt of the tank. The cover of the box is generally a flat plate and is fixed together with the iron yoke clamp.

2.4 Final Assembly

1. Body assembly It includes insulation assembly and coil head dressing treatment, coil set, insert plate and clamp, half-finished test of the body, lead assembly (including switch assembly, lead manufacturing and assembly), half-finished test of the body, and furnace drying of the body (including insulation resistance measurement). 2. Total assembly It includes the finishing and fastening of the body, the measurement of the insulation resistance of the iron core to the ground, the inspection of the cleanliness of the body and the tightness of the components, the insulation distance of the wiring and the lead, the filling of the oil (including the installation of transformer accessories), the test of the transformer factory (such as the insulation resistance, DC resistance value, transformer ratio, voltage resistance test, etc.), and the storage procedure.

03 Testing

Insulation resistance test: test the insulation performance of the transformer, including the insulation resistance between the winding and the winding, the insulation resistance between the iron core and the winding, etc.

Dc resistance test: Test the DC resistance of the transformer winding to verify the connection of the winding and the stability of the resistance.

High voltage test: test the voltage resistance of the transformer, including the leakage current and breakdown voltage under the rated voltage.

No-load test: test the no-load loss, no-load current, iron loss and other parameters of the transformer to verify the operating performance of the transformer.

Load test: test the voltage regulation performance, temperature rise and load loss of the transformer under rated load, stability and reliability under short and long time load conditions.

Short-circuit test: test the heat dissipation and short-circuit current bearing capacity of the transformer in the short-circuit state, as well as the functional detection of the emergency cut-off protection device in the short-circuit.

Whole machine performance test: test the overall operation performance and stability of the transformer, including the stability of the output voltage, efficiency, power factor and other parameters.

04 Packing and Shipping

05 Site And Summary

Thank you for your interest in our three-phase pad-mounted transformer! With its exceptional performance, reliable safety features, and versatile adaptability, this product provides efficient and stable power support for industrial, commercial, and public distribution systems. We are dedicated to placing customer needs at the core of our mission, combining advanced technology with premium services to deliver customized power solutions tailored to you. We look forward to collaborating with you to drive innovation and sustainability in the power industry! For more information or technical support, please feel free to contact us anytime!