Shorted Turn Condition
A completed path by any conductor passing through the center hole of the toroid around the outside constitutes a short-circuited turn. As with any short circuit, this condition will result in high circulating currents and more importantly, high heat.

Our standard mounting options utilize either a single bolt and large washer (disk mount) with no outside structure to act as a conductor, completing the circuit; or two metal flanges (flange mount) which clamp the toroidal like a sandwich with four bolts at the outer periphery, but nothing through the center. The L-Bracket and Clamping Bracket described are both designed to avoid a shorted turn condition.

Inrush Current Condition
The excellent magnetic properties of the toroidal transformer and the high remanence of the grain-oriented silicon steel, under certain circumstances, occasionally leads to high inrush current at turn-on. This is particularly true when the circuit is completed at the zero-crossing of the input voltage wave form.

To prevent nuisance interruptions due to blown fuses or supply breaker, some simple precautions should be considered, As the power rating of the transformer increases, the potential effect of the inrush current becomes greater. The following table suggests different types of circuit protection according to the toroid's power rating.

In addition, in those applications where an even lower in-rush current is desired, AMVECO has developed several proprietary construction techniques, Without added circuitry, both the peak value and the duration of the in-rush current can be reduced. As a matter of fact, AMVECO has manufactured toroidal transformers without any inrush current at all. In these cases, AMVECO works closely with the customer to meet the specific requirements of the application. A slight increase in the overall size of the transformer is sometimes necessary to facilitate the lower in-rush current.