3 Phase Transformer 100 kVA

Nov 13, 2025

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100kVA transformers can be overhead transformers, single phase transformers, three phase transformers, distribution transformers, and dry-type transformers.

To capture a larger market share, HENAN GNEE ELECTRIC CO., LTD. develops designing approaches and production system to fabricate distribution transformers more efficient,specially to the common mode distribution transformers, such as 100 kVA 3 phase step down distribution transformers. To deal with the material costs waving, the company designs solutions of distribution transformer as the current material price to offer an attractive quotation to clients. To ensure the quality,HENAN GNEE ELECTRIC CO., LTD. runs required tests to each 100 kVA 3 phase step down distribution transformer. The company also will send spare parts to clients if any damages occurred in shipping. We wish you would come to our factory for business cooperation.

100kVA Dry Type Transformer

The 100kVA dry-type transformer adopts efficient dry-type insulation technology and is designed for industrial, commercial and residential power systems. With its excellent performance and compact structure, the transformer provides stable and reliable power support and is suitable for small and medium-sized power distribution needs. Through strict quality control, HENAN GNEE ELECTRIC CO., LTD.'s 100kVA dry-type transformer provides users with high-quality, low-maintenance power solutions.

Technical Specifications
Rated Power	100 kVA
Rating Primary Voltage	2.4-34.5kV
Secondary Voltage	480/277V 400/230V 380/220V Customized
Frequency	50/60Hz
Vector Group	Dyn11,Yyn0,Dyn5
Winding Material	Aluminum/Copper
Efficiency	As IEEE,Doe 2016,CAS Std or Customized
Impedance Voltage	Nominal 2% or Customized 1.1-5.75%
Altitude	≤1,000m or Customized
Enclosure material	304 Stainless Steel
Total Weight	500 kg
Outline Dimensions(L×W×H)in.	850×650×1150(mm)

Primary Voltage Ratings:34.5-19.92/13.8-7.957/13.2-7.62/12.47-7.2, 24.94, 26.25, 33 or others

Secondary Voltage Ratings:480/277V,400/230V,380/220V or customized

H.V. Tap Range:± 2×2.5% HV taps or others

Type:Dry type transformer

BIL:30/95kV

Standards:IEEE, ANSI, NEMA,IEC,GB

Application:power systems and distribution networks, office buildings, transportation facilities,theaters, hospitals, hotels etc

Power Rating:100kVA

Certificate:UL ,CESI, ISO

Cooling Method:OA/OF

Opeartion:Step Down & Step Up

Progress Test

To ensure that the 100kVA dry-type transformers produced by NPC Electric have excellent electrical performance, long-term stability and safety, they are tested before leaving the factory. The test content covers electrical performance, temperature rise, load capacity, short-circuit resistance, noise control, insulation performance and other aspects, aiming to verify the reliability and safety of the transformer under various conditions of use.

The insulation resistance and withstand voltage test first strictly tested the insulation system of the transformer. Through the high-voltage withstand voltage test, the transformer performed well in all electrical indicators. The insulation resistance value is much higher than 1000MΩ, proving that its insulation layer can effectively prevent electrical leakage and remain safe and reliable when operating in a high-voltage environment, in line with international electrical safety standards.

The no-load test tests the performance of the transformer under no-load conditions. The test results show that the no-load current and no-load loss are within the design allowable range, and the no-load loss is low, showing that the transformer has a high efficiency of energy utilization. The stability and low energy consumption characteristics of the transformer under no-load conditions meet the customer's requirements for high-efficiency transformers.

Design Tests

All transformer will be test after finished the production, test items as below:
♦ Insulation Power Factor
♦ Winding Resistance
♦ Impulse Tests
♦ On load Loss Test
♦ No Load Loss Test
♦ Leak Test
♦ DC Insulation Resistance Test
♦ Transformer Turns Ratio/TTR (All Tap Voltages)
♦ Impedance Voltage & Load Loss (Rated Voltage)
♦ Excitation & No-Load Loss (Rated Voltage)
♦ Applied Voltage
♦ Induced Voltage
♦ Lightning Impulse
♦ Insulation Resistance (Rated Voltage)
♦ Temperature Rise

Transformer Factory Acceptance Test:

HENAN GNEE ELECTRIC CO., LTD. conducts rigorous quality control testing on every transformer or representative samples, as well as on specific components and materials, to ensure compliance with design specifications throughout the production process.
The Factory Acceptance Test (FAT) for a 100kVA three-phase dry-type transformer is a critical step performed before shipment to verify that the unit meets all applicable standards and delivers optimal performance. The FAT includes the following key procedures:

Visual Inspection: Evaluates the transformer's physical condition, including the enclosure, terminals, and labeling, to ensure conformance with design and safety requirements.
Electrical Testing: Involves measuring winding resistance, insulation resistance, and performing turns ratio tests to validate electrical integrity and functionality.
Dielectric Strength Test: Applies high voltage across the insulation system to ensure it can endure both normal and transient operating voltages without failure.
Load Testing: Simulates real-world operating conditions to assess the transformer's voltage regulation, temperature rise, and overall efficiency under load.
Protection Device Testing: Verifies the proper operation of integrated protective components such as thermal sensors, temperature relays, and tap changers (if applicable).

Routine Test - Winding Resistance

Purpose of Testing

The purpose of winding resistance testing is to detect the continuity and connection quality of the internal conductors of the motor or transformer windings, and to promptly detect potential faults such as open circuits, poor contact or local heating.

Testing Equipment

Winding resistance tester (e.g. OMICRON, DV Power, Raytech, Megger, ISA, etc.)
Test voltage source (commonly used are 6V, 10V, 20V, 40V or 100V, depending on the equipment model or customer requirements)
Temperature and humidity meter (used to record the ambient temperature and humidity during the test)

Pre-Test Preparation

Check if the instrument has been calibrated to ensure the test accuracy.
Disconnect the electrical connection between the test cable and the equipment to ensure that there is no external current or voltage interference.
Select a suitable voltage range for testing and set the test voltage according to the equipment requirements.

Test Progress

Connect the Test Instrument:
Connect the test equipment to the winding terminals of the device under test, making sure the connections are secure and properly grounded to avoid measurement errors.
Apply Test Voltage:
Select the appropriate test current according to the equipment specifications (such as test current for low-voltage windings, single-phase or three-phase windings).

Measure and Record

Start the test and record the following parameters:
Winding resistance (usually expressed in units of "Ω")
Test current (A)
Test voltage (V)
Temperature (record the winding temperature before and after the test)

Temperature Correction

The measured winding resistance values are converted to a reference temperature (usually 20°C) based on a temperature correction formula to allow accurate evaluation and comparison.

Repeat Testing (if necessary)

Test the different windings (high voltage, medium voltage, low voltage) separately and make sure to record the resistance value of each winding.

Evaluation Criteria (Reference)

Resistance deviation is less than 5% (normal)
Resistance deviation is between 5% and 10% (warning)
Resistance deviation exceeds 10% (further inspection or corrective action is required)

Test standard

IEEE C57.12.01 & IEEE C57.12.91 (Dry-Type)

*These comprehensive tests ensure that each transformer meets performance standards and operates reliably under various conditions.