Va Rating On Transformer

Hence the transformer is rated by the VA only.

Va rating on transformer. By Electrical4U Manufacturer designs transformer based on required voltage and current and specified them on the nameplate of the transformer in terms of VA called the rating. 40 VA is Volts times Amps which is typically close enough to 40 Watts for hobbyist purposes. This means that the primary winding and the secondary winding are designed to withstand the VA or kVA ratings stamped on the transformer nameplate. The fuse must be smaller than the VA rating of the transformer.

CTs with larger cores are generally capable of transferring more power. The kVA unit represents kilovolt-amperes or 1000 volt-amperes. Continuing with the example. Calculate the VA rating using the formula VArating Vsecondary x I08 where Vsecondary is the secondary voltage of the transformer and the 08 accounts for the power factor of the load.

For a typical 24 volt secondary this is simply using watts law to calculate amperage. The VA rating of a CT is an indication of how much power the CT is capable of producing. A transformer with a 100 VA rating for instance can handle 100 volts at one ampere amp of current. The transformers used in this application fall in to the dry type insulation category.

A transformer with a 10 kVA rating is the same as a transformer with a 1000 VA rating and can handle 100 volts at 10 amps of current. This will then determine the maximum load that can be connected to the transformer. Suppose the load requirement of a utility to be fed is 85 kW then the kVA rating of transformer should be 85085 100. The total deliverable apparent power is the rating of the transformer.

The power factor of load may be assumed to be 085. Typical primary voltages in the United States are 600 480 240 and 208. Transformer ratings power points are measured in volt-amperes VA or kilovolt-amperes WA. The VA rating is used to select the properly sized fuse for that circuit.

The reason they say VA instead of W is that if your voltage lags or leads current you get VA times cosine of the angle between the V and the A instead of just VA. Again if the source voltage is 11 kV and load is to be fed by 415 V then the rating of transformer will be 100 kVA 11 kV 451 V. Well the wire we use to connect the CT has some resistance to it. Select the number of phases from the drop-down menu Enter the transformer rating and select the appropriate unit Enter the primary and secondary transformer voltages Click on the Calculate button to obtain the results.

Because the secondary must carry all the current of the load regardless of its power factor the limiting factor in delivering power to the load is the RMS current. If V and A are in phase pure resistive load then VA Watts. The methods of selecting transformer VA ratings addressed in this technical paper are applicable to 503000 VA control circuit transformers. Sometimes the transformer can be rated by kVA kilo Volt-Amps or MVA Mega Volt-Amp.

VA stands for volt-amperes. The only thing that goes into a transformers VA rating is the withstand current of the secondary windings or equivalently the acceptable temperature rise. Simply put the VA rating is the math formula used in determining the amperage at a given voltage. It can be also said that the maximum voltage and current that can be safely applied to transformer called the rating.

If we are outputting current one might wonder why we care about power. VArating 208 x 6508 16900 volt-amperes or 169 kilovolt-amperes or 169 KVA.