Compare with the MG set with IGBT , why MG set is more suitable for power transformer tester? Who are major suppliers in China and global?

Your question is actually a classic technical discussion in transformer test floors:

MG set (Motor-Generator) vs IGBT / solid-state frequency converter (SFC).

In practice, many large power-transformer factories still prefer MG sets, especially for induced voltage test and loss measurement. Below is a practical comparison used in transformer plants.

1. MG Set vs IGBT Power Supply for Transformer Testing

MG sets provide independent power supply and stable voltage/current for test systems.  

2. Why MG Sets Are Often Preferred for Power Transformer Testing

2.1️⃣ Strong short-circuit and overload capability

During tests such as:

• Short-circuit impedance test
• Load loss test
• Temperature rise test

the transformer may draw very large transient current.

MG sets tolerate this well because of their rotating inertia, while power-electronic systems can trip or limit current.

2.2️⃣ High power capacity (MVA level)

Large transformer factories may need:

• 5–20 MVA test supply
• Sometimes 30 MVA or more

MG sets scale easily to large capacity.

For example, MG systems are used to test up to 315 MVA / 400 kV transformers in some factories.  

IGBT power supplies at this level become very expensive and complex.

2.3️⃣ Extremely stable sinusoidal waveform

Loss measurement requires very accurate waveform:

• Core loss test
• Load loss test

MG sets produce a natural sine wave from a synchronous generator.

IGBT supplies generate PWM waveform and need filters, which may still introduce harmonics affecting measurement accuracy.

2.4️⃣ Electrical isolation from the grid

MG sets provide mechanical isolation between grid and test object, which helps:

• Reduce grid disturbances
• Improve measurement stability
• Protect the grid during high-power tests.

2.5️⃣ High-frequency output for induced test

Power transformer induced voltage test often requires:

• 100 Hz
• 150 Hz
• 200 Hz

MG sets easily produce these by changing generator speed or pole configuration.  

3. Why Some Factories Are Moving to IGBT Systems

Despite MG advantages, modern IGBT / Static Frequency Converter (SFC) systems are becoming popular because:

• smaller footprint
• automated control
• fast startup
• less mechanical maintenance.

They also allow fully automated test floors and flexible voltage/frequency programming.  

So many new test laboratories combine both technologies.

4. Major Global Suppliers (Transformer Test Power Systems)

Leading global suppliers

• Siemens Energy – large transformer test systems
• OMICRON Electronics – transformer diagnostic and test systems
• Doble Engineering Company – advanced transformer testing solutions
• Megger Group – electrical power testing equipment manufacturer  
• HIGHVOLT Prüftechnik Dresden – high-voltage and test lab equipment

These companies mainly supply complete transformer test laboratories.

5. Major Chinese Suppliers (MG Set / Test Systems)

China has many suppliers for transformer factory test floors.

Equipment integrators

• Shanghai Trihope
• Wuhan Huatian Electric Power Automation
• Ponovo Power

These companies typically provide:

• MG sets
• induced test systems
• loss measurement systems
• complete transformer test laboratories.
  
  
  6. Industry Reality

   

  In most large power transformer factories (>220 kV):

   

  Typical configuration:

  MG SET---induced voltage test

  MG SET---load loss test

  IGBT/SFC --- Auxiliary variable supply

   

  So MG sets are still the backbone of high-power test floors, while IGBT systems provide flexibility