I. Introduction 
 Measured with a variable ratio transformer bridge ratio, complicated operation, measuring a narrow range, no longer meet the fast pace of modern measurement and high efficiency requirements. To this end, I am using modern electronic technology, developed a new generation of automatic change than group tester. It is small, light weight, high precision and good stability. It uses a large-screen character display, menu operation, friendly interface. Variable than the group can complete a test. The instrument is ideal for testing electrical equipment industry. 
 Second, the main functions and features 
 1. Automatic measurement wires. 
 2. Automatically group transformation, can be measured directly for all the transformer ratio. 
 3. Automatic switching phase sequence. 
 4. Automatic switching range. 
 5. Automatic calibration. 
 6. Enter the standard variable ratio, can automatically calculate the relative error. 
 7. A measurement is completed, automatically cut off the test voltage. 
 8. Set of data, measurement results are automatically saved, you can view the previous data. 
 Third, the major technical indicators 
 1. Variable than the measurement range: 1-10000 
 2. Group :1-12 
 3. Accuracy: 1-1000 1000-10000 0.5 0.2 
 4. Power Supply: AC220V ± 10%, 50HZ 
 5. Ambient temperature: -5 ℃ ─ 40 ℃ 
 6. Ambient humidity: <85% 
 7. Sizes: 430 × 320 × 215mm3 
 8. Weight: 8Kg