Control Transformers Low-voltage Control Transformer

Control transformers are specifically designed for low-voltage control circuits, with the following key features and applications:

Core Characteristics

1. Electrical Parameters

- Frequency compatibility: Supports 50Hz/60Hz power frequency

- Voltage range: ≤1000V AC

- Duty cycle: Capable of 100% rated load continuous operation

- Insulation class: Typically Class B (130°C) or Class F (155°C)

2. Performance Features

- Precise voltage conversion (common ratios: 380V/220V/110V/36V/24V/12V, etc.)

- High stability (voltage regulation ≤5%)

- Short-circuit resistant design (secondary windings can withstand instantaneous overloads)

Typical Applications

1. Industrial Equipment

- Machine tool control systems (power supply for PLCs, relays, contactors)

- Production line equipment (power for sensors, solenoid valves)

- Hoisting machinery (isolated power for control circuits)

2. Safety Power Supply

- Provides safety voltage (36V and below) for:

- Equipment local lighting (protection rating up to IP65)

- Warning indicator lights (LED/neon light power supply)

- Operation power in humid environments

3. Special Functions

- Electrical isolation between primary and secondary circuits

- Suppresses grid harmonics interfering with control systems

- Multi-winding design allows simultaneous output of different voltage levels

Key Selection Criteria

1. Capacity Calculation

- Total capacity = 1.2 × (control load + lighting load + reserve capacity)

- Common specifications: 50VA, 100VA, 200VA, 500VA, 1kVA, etc.

2. Protection Requirements

- For machine tools: Oil-mist resistant design

- Outdoor use: Weatherproof enclosure

- Explosion-proof applications: Encapsulated construction

3. Safety Certifications

- Must comply with IEC 61558 or GB 19212 standards

- Additional certifications required for medical/shipboard applications

Maintenance Guidelines

- Regularly check winding temperature rise (normal ≤80K)

- Monitor no-load current (abnormal increase may indicate interturn short circuits)

- Secondary circuits must include overcurrent protection

- Measure insulation resistance periodically in humid environments (≥1MΩ)

The key difference between these transformers and power transformers lies in their focus on voltage stability rather than transmission efficiency. They are typically constructed with cold-rolled silicon steel sheets and Class H insulation materials, featuring compact size and fast dynamic response. In automated equipment, their power supply quality directly impacts control system reliability. Therefore, models with electrostatic shielding are recommended to enhance noise immunity.