1. Standard: GB1094.1-1996,GB1094.2-1996, GB1094.3-2003, GB/T6451-2008,GB1094.5-2003
2. Product type code: D-single-phase, S-three-phase, F-air cooling, Z-on-load tap-changing
3. Performance level code: 7,8,9,10,11,12
4. Certification: ISO9001, CNAS, IAF, CE