Product Overview

The ST Series Step Up & Step Down Autotransformer is a versatile single-phase voltage converter designed for bidirectional voltage conversion between 110V and 240V. Featuring multiple selectable input voltage settings, it allows users to safely operate electrical equipment designed for different international voltage standards.

As a non-isolated autotransformer, the ST Series offers a compact design, high conversion efficiency, and low energy loss. Equipped with a built-in C45 miniature circuit breaker (MCB), rear fuse protection, and a durable metal enclosure, it provides reliable performance for residential, commercial, industrial, laboratory, and maintenance applications.

The series is available in capacities from 500VA to 10,000VA, with the ST-1000VA model being one of the most popular choices.

Note: This is a non-isolated autotransformer. The input and output share a common electrical connection.

Key Features

Bidirectional 110V ↔ 240V Voltage Conversion

The ST Series supports both step-up and step-down voltage conversion, making it ideal for operating imported electrical equipment worldwide.

Features include:

110V to 240V step-up conversion
240V to 110V step-down conversion
Selectable input voltages: 110V / 200V / 220V / 240V
Dual 110V output outlets
Dual 240V output outlets
Compatible with both 50Hz and 60Hz power systems

The autotransformer design provides high efficiency, compact size, and lower weight compared with isolation transformers.

Multiple Capacity Options

The ST Series is available in a wide range of power ratings:

ST-500VA
ST-1000VA
ST-1500VA
ST-3000VA
ST-5000VA
ST-10000VA

For reliable operation, selecting a transformer with 20–30% reserve capacity above the connected load is recommended.

ST Series Step Up & Step Down Autotransformer (110V/240V Bidirectional Voltage Converter)

Comprehensive Safety Protection

Designed for safe and reliable operation, the ST Series incorporates multiple protection features.

C45 Miniature Circuit Breaker

The front-mounted C45 circuit breaker provides:

Overload protection
Short-circuit protection
Quick power disconnection
Easy reset after fault clearance

Rear Fuse Protection

An independent rear-mounted fuse provides secondary protection for enhanced equipment safety.

Efficient Cooling Design

The heavy-duty metal enclosure features large ventilation slots that improve airflow and reduce operating temperature during continuous use.

Power Status Indicator

A green LED power indicator allows users to quickly confirm the operating status of the transformer.

Durable & User-Friendly Design

The ST Series is engineered for convenient daily operation.

Front Panel

Two 110V universal output sockets
Two 240V universal output sockets
Clearly labeled voltage outputs
C45 circuit breaker switch
Green power indicator

Rear Panel

Multi-position input voltage selector
Integrated AC power cord
Replaceable fuse holder

Portable Construction

Features include:

Reinforced carrying handle
Compact desktop design
Heavy-duty metal housing
Corrosion-resistant finish
Easy transportation and storage

Technical Specifications (ST-1000VA)

Item	Specification
Model	ST-1000VA
Product Type	Step Up & Step Down Autotransformer
Rated Capacity	1000VA
Phase	Single Phase
Input Voltage	110V / 200V / 220V / 240V AC (Selectable)
Output Voltage	110V AC / 240V AC
Frequency	50Hz / 60Hz
Transformer Type	Non-Isolated Autotransformer
Protection	C45 Miniature Circuit Breaker + Rear Fuse
Cooling Method	Natural Air Cooling
Housing Material	Metal Enclosure
Installation	Desktop / Portable
Color	Black

Typical Applications

The ST Series Autotransformer is widely used for voltage conversion in residential, commercial, and industrial applications.

Imported Household Appliances

Refrigerators
Washing machines
Ovens
Home theater systems
Audio equipment
Coffee machines

Medical Equipment

Ultrasound equipment
Diagnostic instruments
Medical laboratory devices

Industrial Equipment

CNC machines
Industrial robots
Manufacturing equipment
Production machinery
Automation systems

Laboratory Instruments

Microscopes
Analytical instruments
Testing equipment
Research laboratory devices

Electrical Maintenance

Digital multimeters
Power tools
Electrical testing equipment
Repair workshops

Commercial Equipment

Office equipment
Imported printers
Retail equipment
Commercial machinery

Operating Instructions

1. Verify the rated voltage and total power consumption of all connected equipment.

2. Select an autotransformer with sufficient capacity.

3. Connect the transformer to the local AC power supply.

4. Set the rear voltage selector to match the local mains voltage (110V, 200V, 220V, or 240V).

5. Connect the equipment to the appropriate 110V or 240V output socket.

6. Switch on the front C45 circuit breaker.

7. The green power indicator will illuminate, and the transformer is ready for operation.

8. When shutting down, first turn off the circuit breaker before disconnecting the connected equipment.

Important: Do not exceed the transformer's rated capacity. Always follow the operating instructions and safety guidelines provided in the user manual.