630 kVA Dry Type Step Down Transformer-11/0.55 kV | South Africa 2024

Efficient cooling, low maintenance-VPI Dry-Type Transformer you can trust.

01 General

1.1 Project Description

The 630 kVA dry type step down transformer was delivered to South Africa in 2024. The rated power of the opening winding dry type transformer is 630 kVA with AN/AF cooling, the primary voltage is 11 kV with ±2*2.5% tapping range (NLTC), the secondary voltage is 0.55kV, they formed a vector group of Dyn11.

The glass fiber unfilled resin casting structure can achieve the same power frequency and impact level as the oil-immersed transformer. This dry type step down transformer has been able to withstand the test voltage (high voltage to high voltage, high voltage to low voltage to ground) and the operating voltage in the atmospheric environment. There is only a small pressure difference between turns, layers and segments of the winding, which is borne by the resin itself and reaches a very safe level. The voltage between layers of foil-wound winding is only very small voltage per turn, the winding end has no spiral Angle, the magnetic leakage area is small, and the axial short-circuit resistance is strong.

1.2 Technical Specification

630 kVA dry type step down transformer specification and data sheet

1.3 Drawings

630 kVA dry type step down transformer diagram drawing and size.

02 Manufacturing

2.1 Core

The role of the dry transformer core is to form a magnetic circuit. In order to reduce eddy current loss, the core is made of a thin silicon steel sheet staggered. The surface of the silicon steel sheet is coated with insulating paint and oxidized to form an insulating layer. The core is mainly composed of an iron core body, fasteners and insulating parts. Fasteners and insulating parts are composed of clamp, screw, glass binding tape, steel binding tape, pad and clamp insulation, insulation pipe and insulation pad, ground lug and foot.

2.2 Winding

Vacuum casting can obtain uniform insulation structure, eliminate bubbles and voidings, and avoid partial discharge inside the winding: foil winding between layers low voltage, will not cause partial discharge. According to IEC60076, partial discharge tests should be carried out on a fully assembled transformer. In order to confirm that the design and production have a high quality level, partial discharge tests are carried out on each high voltage winding before assembly. In this way, you can check whether the insulation in the high voltage winding meets the quality requirements. The partial discharge termination voltage is at least 1.2 times the rated voltage, and in most cases, even up to 2 times the rated voltage. Through this test, it is proven that there is no problem in winding local discharge.

2.3 Temperature Control System

Built-in PT100 probes in 3 phase windings to detect the real-time temperature of windings and cycle display temperature in the digital screen. Circuit open alarm and fault self check alarm display and output 3 stage actions: when the temperature reached to the set value, the cooling fans start automatically at 1st stage high temperature alarm at 2nd stage over temperature trip at 3rd stage Fans manual/auto control switch Fans timing start/stop History data record and output Power supply voltage 110V

2.4 Final Assembly

Assembly process 1. Equipment assembly: First of all, the assembly of the equipment, including the assembly of core, isolator, winding, etc. 2. Determine the location of the device: Determine the location of the device according to actual requirements to ensure that the device can be assembled smoothly. 3. Prepare connecting parts: In order to ensure the normal operation of the entire equipment, it is necessary to prepare a variety of connecting parts in advance, including gaskets, bolts, washers, spring gaskets, etc. 4. Assemble the isolator: First, assemble the isolator, including the assembly of the isolator frame, the isolator shell, the isolator plate, the separator, etc. 5. Assemble the winding: Install the winding into the isolator, and pay attention to the quality of the insulation material, as well as the accurate control of the winding length, cross-sectional area and other parameters. 6. Install the connector: Connect the device according to the prepared connector to fix and protect the device. 7. Insulation treatment: In order to ensure the safe operation of the equipment, it is necessary to carry out insulation treatment, such as coating insulating paint and coating insulating materials. 8. Verify the device: Verify the device to test whether the parameters of the device meet the requirements. 9. Factory inspection: The final factory inspection to ensure the normal operation of the equipment.

03 Testing

1. Insulation resistance measurement: For each winding of the dry transformer, insulation resistance measurement is required. This can check whether the insulation material meets the standard requirements.

2. Volt-ampere characteristic measurement: Volt-ampere characteristic measurement is a test to check the short circuit and open circuit of all windings of a thousand type transformer. At the same time, it can also measure its rated capacity, load loss, no-load loss and voltage regulation characteristics.

3. Insulation strength test: The test checks the voltage resistance of the insulation material, and measures the insulation strength of the transformer through the pressure test.

4. Variable ratio measurement: Variable ratio measurement is a test to check the transmission characteristics of a thousand type transformer. This can check whether the transformer ratio is stable under different load states.

5. Short circuit test: Short circuit test is a test for measuring dry transformer loss and temperature rise. This helps to check whether the transformer is operating properly under short circuit conditions.

6. Mechanical stability test: The test checks the dry-type transformer’s ability to withstand mechanical stress. The amount of axial displacement and deflection caused by distortion and torque are measured by applying force.

04 Packing and Shipping

05 Site And Summary

Thank you for your interest in dry type step down transformer! Our products are renowned for their exceptional performance, reliable quality, and eco-friendly design, dedicated to providing efficient and safe power solutions across various industries. Whether for industrial applications, commercial buildings, or specialized requirements, VPI dry-type transformers are always your trusted choice. We look forward to working with you to drive a sustainable future together. For more information or personalized support, please feel free to contact our professional team!