High-Quality Single Phase Adjustable Variac Transformer 0.5kVA-50KVA

Working Principle

The variac transformer operates as an adjustable autotransformer.
A carbon brush is mounted on a circular coil wound evenly on a toroidal iron core. When the handwheel rotates, the brush slides along the polished coil surface, changing the contact point. This adjustment modifies the turns ratio between the primary and secondary windings, allowing the output voltage to vary continuously and smoothly within the rated range.

This design ensures:

• Seamless voltage adjustment (no step changes or distortion)

• High electrical efficiency with minimal power loss

• Durable mechanical operation and stable long-term performance

Product Structure

1. Single Unit Structure (0.5–10kVA)

Each unit includes a polished copper coil fixed on a base and a spring-loaded carbon brush ensuring firm contact. Turning the handwheel adjusts the output voltage smoothly. These compact tabletop models feature a protective ventilated mesh housing for safety and cooling.

2. Assembled Single Phase Structure (≥10kVA)

Large-capacity single-phase models combine several identical units connected in parallel, with all brushes mounted on a shared main shaft. A balancing reactor is integrated to stabilize current distribution and suppress circulating currents between units.

3. Carbon Brush Assembly

• For ≤3kVA units: uses 1–2 copper-graphite composite brushes with excellent conductivity and wear resistance.
• For ≥4kVA units: uses dual composite brushes with enhanced heat dissipation and precision contact pressure adjustment.

Product Parameters

Output Voltage Accuracy: ±1%
Waveform Distortion: None (pure sine wave output)
Electrical Strength: 1500V / 1 min
Humidity Range: 5–90% RH (non-condensing)

Environmental Requirements

To ensure optimal performance and long service life, the single phase variac transformer should operate under proper environmental conditions:

1. Temperature: -10°C to +40°C

   • Avoid excessive heat, which accelerates component aging and affects voltage accuracy.

   • Avoid extreme cold that increases internal resistance and reduces efficiency.

2. Humidity: 5%–90% RH (non-condensing)

   • Prevent condensation or water intrusion to avoid short circuits and corrosion.

3. Electromagnetic Environment:

   • Should be installed away from strong electromagnetic sources such as motors or inverters.

   • Use shielding or filters if interference is unavoidable.

4. Installation Space:

   • Ensure at least 10–15 cm of clearance around the transformer for proper ventilation and cooling.

Applications

• Industrial Machinery: Voltage regulation for CNC, injection molding, and automation systems.
• Electrical Laboratories: Precision voltage adjustment during testing and calibration.
• Lighting & Stage Equipment: Smooth dimming and lighting control.
• Heating Equipment: Temperature regulation for furnaces, ovens, and drying systems.
• Power Supply Systems: Voltage stabilization for sensitive instruments.
• Educational & R&D Institutes: For teaching, prototyping, and research testing setups.

Advantages

• Smooth and continuous voltage control without waveform distortion.
• Compact structure and low noise design.
• High mechanical strength and long brush life.
• Stable performance under varying load conditions.
• Overload and overcurrent protection options available.
• Customizable capacity, input/output range, and casing design.

Why Choose Our Variable Transformers

With over 20 years of experience in transformer R&D and production, ZHENGXI has established itself as a trusted variable transformer manufacturer serving global markets. Our products meet CE and CQC certifications and are known for:

• Superior quality materials (pure copper winding & toroidal core)
• Rigorous testing for insulation, efficiency, and performance
• Custom-built designs from 0.5kVA up to 50kVA
• Competitive pricing and fast global delivery

FAQs

Q1: What is the main purpose of a Variac Transformer?
A: It allows continuous voltage adjustment to match different equipment requirements or simulate voltage conditions in testing.

Q2: Can I use it for both step-up and step-down functions?
A: Yes. It can regulate voltage within its range, functioning as both a step-up and step-down transformer depending on configuration.

Q3: Is the transformer suitable for inductive loads like motors?
A: Yes, but ensure the rated capacity exceeds 1.25× the motor’s power to handle startup surges safely.

Q4: Do you provide customized voltage ranges or housings?
A: Absolutely. ZHENGXI offers OEM & ODM customization for voltage, power, and enclosure design based on your requirements.