What Is The Va Rating On A Transformer

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.

What is the va rating on a transformer. Maximum output current is then VA rating divided by nominal output voltage. The transformer rating is 11 MVA. But Primary Voltages or High Voltages HV is 11000 V 11kV. Calculate the transformer rating from Watts.

The power factor of load may be assumed to be 085. This is the highest level of rms primary fault current which the CT can endure both thermally and dynamically for 1 second without damageWhen used in a medium voltage enclosure the I th rating should match the short-time withstand rating of the entire switchgear. The rating is the load carrying capability of the machine. And Primary Current on High Voltage side is 525 Amperes.

S VA P W x pf. To calculate VA you need to know the supply voltage and the current delivered to the load. 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. Go back to Content Table 14 Rated thermal short-time withstand current.

Here is the rating of Transformer is 100kVA. So how does this work. Transformers are rated in VA or kVA. VA stands for volt-amperes.

KVA rating from W. Volt-ampere VA is a measurement of power in a direct current DC electrical circuit. The fuse must be smaller than the VA rating of the transformer. The VA rating refers to the power distribution rating relative to how much power the transformer can deliver to the load.

VA ratings are also often used for transformers. If we are outputting current one might wonder why we care about power. Well the wire we use to connect the CT has some resistance to it. 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.

Transformers with the same sized core usually have the same VA rating. A transformer with a 100 VA rating for instance can handle 100 volts at one ampere amp of current. But the alternator and the transformer are the only machines which are rated in volt-amp VA. Continuing with the example.

That is because the voltage is limited by the power loss in the magnetic core and the current is limited by the power loss in the resistance of the windings. For measuring current and voltage of the kVA and MVA rating we use a potential transformer and current transformer. The kVA unit represents kilovolt-amperes or 1000 volt-amperes. The VA rating of a CT is an indication of how much power the CT is capable of producing.

VA rating of the transformer is equal to real power P W divided by power factor. 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. Most loads are labeled with their proper operational voltage Volts current Amps frequency Hz and wattage Watts or VA. It can be also said that the maximum voltage and current that can be safely applied to transformer called the rating.

In a DC circuit 1 VA is the equivalent of one watt 1 W. This will then determine the maximum load that can be connected to the transformer. The machines are always rated in watts. For example a 1KW 1000 Watts load would require a 1kVA transformer unity power factor.

The VA specification is also used in alternating current AC circuits but it is less precise in this application because it represents apparent power which often differs from true power. Suppose the load requirement of a utility to be fed is 85 kW then the kVA rating of transformer should be 85085 100. Also Secondary voltages or Low Voltages LV is 415 Volts. It shows the maximum value of the voltage at which the machine is designed and the current consumption occurs at that voltage.

The VA rating of a transformer is its thermal capability. Simply put the VA rating is the math formula used in determining the amperage at a given voltage. The size of a transformer is determined by the kVA of the load. The VA rating is used to select the properly sized fuse for that circuit.

The load has a VA volt-ampere rating. You get the supply voltage from the voltage specifications associated with the primary and secondary windings. Watt is the unit of the real power P W. At the same time the windings of the transformer.

Transformer capacity is rated in Volt-Amps VA which is generally the same as wattage Watts. Figure 1 Current transformer nameplate. VArating 208 x 6508 16900 volt-amperes or 169 kilovolt-amperes or 169 KVA. Transformers are made from materials that have an inherent ability to deal with heat.

CTs with larger cores are generally capable of transferring more power.