As one of the important parameters to measure the quality of the ring transformer, the no-load current refers to the rated voltage applied to the primary winding when all the secondary winding are open, and the value of the current through the primary winding reflects the quality of the transformer to a certain extent. Today, I will briefly introduce the main factors affecting the no-load current of the ring transformer.
The main factors affecting the no-load current of the ring transformer are as follows:
(1) Winding turns.
In the case of the same technical specifications of the ring transformer, the less the turns of the primary winding, the greater the no-load current.
(2) Core size.
In the case of the same technical specifications of ring transformer, the smaller the core size (cross-sectional area and magnetic circuit length), the larger the no-load current.
(3) Core material.
According to the permeability (μ), iron core materials can be divided into three categories: low μ, medium μ and high μ. In the case of the same core size and winding turns and other technical specifications, the higher the magnetic conductivity coefficient, the smaller the no-load current. Most of the ring transformers are made of medium μ silicon steel.
In addition, the thickness of the silicon steel sheet and the conductivity between the silicon steel sheets also affect the primary no-load current of the ring transformer. In general, the thicker the silicon steel sheet is, the smaller the resistance between adjacent silicon steel sheets is, the greater the eddy current loss in the core after power on, and the greater the primary no-load current of the ring transformer.
(4) Manufacturing process.
The quality of manufacturing process is also closely related to the size of no-load current. The copper wire winding should be tight and solid, and the winding and iron core should be as compact as possible, otherwise the no-load current will also be increased. After winding the ring transformer, if it can be soaked and dried, it will also help to reduce the no-load current and improve the quality of the ring transformer.
The no-load current consists of magnetizing current (producing magnetic flux) and iron loss. The larger the no-load current is, the greater the loss is to some extent. At present, the ring transformer with poor quality produced on the market not only has large no-load current and is easy to generate heat, but also makes AC hum when it is powered on.