Enter the total number of amps and select the transformer size to determine the maximum overcurrent protection.

## Fusing Transformer Formula

The following formula is used to calculate the maximum over protection current a fusing transformer should support.

FS = TA * OF

• Where FS is the fusing overcurrent protection amps
• TA is the transformer primary current (amps)
• OF is the overcurrent protection factor
• = 125 % for 9 amps or more
• = 167% for 2-8.99 amps
• = 500% for less than 2 amps

## Definition

What is fusing transformer?

Fusing transformer is the process of protecting a transformer with fusing so that it can handle larger amounts of current.

## Example Problem

how to calculate overprotection for fusing transformer?

First, determine the total amperage the transformer will see. In this example, the total amperage is 7 amps.

Next, reference the list above for how much of an overprotection factor the transformer should have. In this case, it is 167%

Finally, calculate the fusing transformer amperage required:

FS = TA * OF

FS = 7 * 1.67

FS = 11.69 amps