# How do you determine the size of a transformer fuse?

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## How do you calculate what size fuse you need?

The fuse rating can be calculated by dividing the power used by the appliance by the voltage going into the appliance. I (Amps) = P (Watts) ÷ V (Voltage).

## Which fuse is used in transformer?

The ABB WBP fuse has a high capability up to 120kA and temperature control units increase application safety for gas insulated panels, switchgear and electrical equipment up to 40.5kV. The WBP fuse links are used to protect switchgear equipment against short circuits in voltage transformers.

## How do you size a breaker for a transformer?

Iprimary = (20 x 1000)/480 = 20,000/480 = 41.6 amps. Note: If you had a 3-phase transformer, the formula would be Iprimary = KVA x 1000/(Vprimary x 1.732). The 1.732 accounts for the 3-phase configuration. Find the circuit breaker size for the primary side of the transformer by multiplying Iprimary by 1.25.

## What are the standard fuse sizes?

Manufacturers have now standardised plug fuse ratings to be either 3A or 13A. However, 5 Amp fuses are still used in some older equipment and are available to buy.

## What is the fuse rating of 100 kva transformer?

100 A & 200A fuse respectively.

## How do I choose the right fuse?

How to Choose the Right Fuse

1. Identify the type of voltage that is being protected. …
2. Observe the amperage of the electrical circuit that the fuse will be protecting. …
3. Size the fuse to its particular holder. …
4. Inspect the fuse for internal element replacement. …
5. Use a fuse that has an inspection window.
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## How do you protect a transformer from overload?

The protection of a transformer against the overloads is performed by a dedicated protection usually called thermal overload relay. This type of protection simulates the temperature of the transformer’s windings. The simulation is based on the measure of the current and on the thermal time constant of the transformer.

## Why choosing the right size of fuse is important?

Choosing the right fuse ensures ongoing equipment function and prevents expensive maintenance due to nuisance blows. … At 60C, for example, a circuit that would use a 1-A time-delay fuse at room temperature will need a 1.25-A fuse to support operation at the higher temperature (see Fig. 1 ).