According to the introduction of foreign literature, toroidal transformers can be divided into three categories: standard, economical and isolated, and the characteristics of each type are:
Standard power transformer products
The series capacity is 8~1500VA, with small voltage regulation, and the temperature rise at full load is only 40°C, which allows short-term overload operation, and is suitable for high-demand use occasions. The primary winding is insulated with grade B (130°C) polyester film, which is required to be wrapped with at least three layers of insulating tape, which can withstand the withstand voltage test of AC 4000V and 1min.
Economical power transformer products
The series capacity is 50~1500VA, and strives to reduce the cost on the basis of ensuring performance, which is suitable for continuous operation without overload, the operating temperature rise is 60 °C, the insulating material grade is Class A (105 °C), and the output voltage error is less than 3% when the load is full.
Isolation transformer products
The series capacity is 50~1000VA, and it can be divided into two series: industrial and medical equipment. The isolation transformer focuses on its insulation performance, and the primary and secondary are wrapped with B-class insulated polyester film at least 4 layers, and the breakdown voltage is greater than 4000V. The maximum temperature rise of the transformer is less than 45°C.
Isolation transformers for medical use
In addition to meeting the above requirements, the isolation transformer for medical use must also meet the UL544 standard, that is, the primary and secondary windings should have thermal protection, and the distance between the windings and the grounding copper shield should be greater than 13mm.