ER4045/H ER4245 ETD4949H Mid to High Power Transformer Selection Guide PART NUMBER SERIES EE1916 EPC19 EF20 EFD20 EE2219 EPC25 EFD25 EE2519 EE2820 ER2828 ER2834/H ETD2929/H ETD3434H ER3541/H ER3944 ETD3944H ER4045/H ER4245 ETD4949H 密封型变压器 Single Primary Part Number