Power: 3-10.000 VA mono-phase, 10-30.000 VA three-phase;
Primary voltage: 220V; 380V; on request;
Secondary voltage: up to 5000V;
Variable number of windings;
Flash tested: 4kV peak;
Frequency: up to 400Hz;
Insulating materials: class E (120C), B (130C), F (150C), H (180C);
Protection class: IP 00.
The magnetic stray field :
The toroidal transformers have a stray magnetic field almost 10 times smaller comparing to laminated transformers. This advantage owes to the construction of the core, which is wound from a continuous ribbon of steel, and to the windings that uniformly encase the core in cooper like a shield, so the magnetic field is held inside the transformer. This way the need for special screening protection can be eliminated, toroidal transformers being suited for sensitive electronic applications like amplifiers, medical equipment, etc.
Protection against short circuit and overload:
1. Transformers that do not resist the short circuit will be protected using a fuse in the primary circuit. The code of these transformers will contain the letters TH.
2. Transformers that resist at the short circuit and that are protected by incorporated devices will have marked on the label the melting temperature for the thermal fuse and will contain the letters TH in the transformer code.
It is also recommended to protect it by using a fuse in the primary circuit.
The excellent magnetic properties of the toroidal transformers can cause a high magnetizing current on turn on. Normally the duration of the inrush current is less than 10 ms and produces no problems in smaller power transformers.
For higher power transformers we recommend the following types of protection:
1. 15 VA – 300 VA – no protection needed.
2. 300 VA – 1 kVA – slow blow fuse.
3. 1 kVA – 2 kVA – small value resistor in series with primary circuit.
4. 2 kVA – 10 kVA – NTC thermistors or start-up circuit like in figure 1.
All our products are made according to customer’s requests.