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75 kV.A is the rated apparent power of the transformer which it can supply, continuously, to a load without overheating. When the transformer is not supplying a load, the primary current is (a) very small and, (b) lagging the supply voltage by practically 90 electrical degrees. Bear in mind that energy losses only occur for the component of current that is actually in phase with the supply voltage. So the energy consumed to the transformer is very small and is due to the resistance of the primary winding (copper loss) and a relatively small loss in the core (iron loss). Just how much energy this accounts for and, therefore, how much it costs to run the off-load transformer, is not possible to tell without knowing the full specification of the transformer.

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Can a 5.8 ampere 110V run on a step up step down 300 W transformer?

No because the load is 638 VA which is too much for the transformer.


Why transformer rating is not given in kw?

Transformer rating is based on the maximum temperature a transformer can run at. This temperature is dictated by the amount of current flowing through the transformer windings. This is why transformers are rated in KVA (voltage * current), not kW - it doesn't matter what the phase relationship is between voltage and current, just the magnitude of the current.


Up to how much years we can use a 1000 kva transformer?

It depends on the transformer design, type, cooling, maintenance, fault experiences, operating temperature, and loading (I'm sure there's other things that impact it as well). A lot of equipment is rated for 10-20ish years of operation; I would assume your transformer may fall under that. That does not mean that it is dead after 20 years though; I know of several >10MVA transformers that are 60+ years old and still in use. Some have been rewound, some have not. And it doesn't mean that it is 100% guarunteed to run for 20 years. A really bad fault with slow clearing time could cook it the day after you install it.


What will happen if a modified sine wave inverter with 115 Volts output is used as a power source wherein a step up transformer is plugged into it to get a power output of 220 Volts?

It will work, but the transformer will not be able to supply its full rated load, because of the harmonic distortion of the non-sine wave output of the inverter. The transformer will also probably run a little hotter too. If you are talking a small load fed from a transformer much larger than required, probably nothing to worry about. But if the power level is large, or you are loading the transformer to more than 30 or 40% of its rated VA, you could run in to trouble. Monitor voltages and temperatures carefully (and have a fire extenguisher handy...)


What is the reason to use open circuit and short circuit methods to find Transformer losses?

The transformer can be tested on open and short circuit to find the iron losses and copper losses separately, which uses a fraction of the power than having to run the transformer on full-load.

Related Questions

How much load you can run on 62KVA Genset?

max.load that can run on 62 kva dg is of 86 amperes.


Can a 5.8 ampere 110V run on a step up step down 300 W transformer?

No because the load is 638 VA which is too much for the transformer.


What KVA generator is required to run two AC of 1.5 ton?

How much KVA generator is required to run two AC of 1.5 tone


How many 240 volt 4.9 amp draw lights can be run on a 15 kva 2 phase transformer?

To calculate the number of lights that can be run on the transformer, use the formula: Power (kVA) = Voltage (V) x Current (A) x √2 x Number of Phases. Rearranging the formula: Number of lights = (Power (kVA) / (Voltage (V) x Current (A) x √2). Plugging in the values: 15 kVA / (240 V x 4.9 A x √2) ≈ 6 lights.


Why transformer rating is not given in kw?

Transformer rating is based on the maximum temperature a transformer can run at. This temperature is dictated by the amount of current flowing through the transformer windings. This is why transformers are rated in KVA (voltage * current), not kW - it doesn't matter what the phase relationship is between voltage and current, just the magnitude of the current.


Why does your 24 volts transformer get hot then burn out?

A transformer gets hot if it is run at excessive voltage or excessive current. Either of those two would cause it to overheat. <<>> It sounds like the load on the secondary is greater that what the transformer can supply. A transformer is wound for a specific amperage output at a specific voltage. This is stated on the transformer as a VA or in larger transformers as KVA. If you divide the 24 volts into the VA listed on the transformer you will get the maximum amperage value of the transformer. If the device that you are connecting to the transformer is greater in amperage draw that what the transformer can supply, this will cause the heating effect and if left connected eventually burn the transformer out. A fuse should be installed in the secondary 24 volt output, rated at the maximum output of the transformer. This will limit the transformer to its manufacturer's recommended current output.


Where does hysteresis in a transformer depend on?

The power lost by hysteresis depends on the peak flux density in the core. If the transformer is getting hot even when on no load, it should be run at a lower voltage.


Is it dangerous to run an appliance with more watts than the transformer?

A transformer has a rating that is usually expressed in KVA. This is approximately a wattage rating. It is not dangerous but it can be the cause of some concern. An appliance has a set current that is draws. This current times the voltage is the appliance's wattage. The same goes for the transformer. It only has a certain capacity to supply a specific current that is governed by its KVA (watts). Driving the transformer beyond its rated capacity tends to heat the transformer beyond its working temperature. If left in this over current draw the transformer's windings insulation will break down and the windings will short circuit. This is usually the end of a working transformer. So short answer, more watts (amps) from appliance equals burned out transformer.


Why to run a oil cooled new transformer at no load for minimum 24 hours after new installation?

I am guessing at this one but probably to warm the oil so as to assure proper flow and prevent thermal shock once the transformer and its components are heated up under load.


Up to how much years we can use a 1000 kva transformer?

It depends on the transformer design, type, cooling, maintenance, fault experiences, operating temperature, and loading (I'm sure there's other things that impact it as well). A lot of equipment is rated for 10-20ish years of operation; I would assume your transformer may fall under that. That does not mean that it is dead after 20 years though; I know of several >10MVA transformers that are 60+ years old and still in use. Some have been rewound, some have not. And it doesn't mean that it is 100% guarunteed to run for 20 years. A really bad fault with slow clearing time could cook it the day after you install it.


What will happen if a modified sine wave inverter with 115 Volts output is used as a power source wherein a step up transformer is plugged into it to get a power output of 220 Volts?

It will work, but the transformer will not be able to supply its full rated load, because of the harmonic distortion of the non-sine wave output of the inverter. The transformer will also probably run a little hotter too. If you are talking a small load fed from a transformer much larger than required, probably nothing to worry about. But if the power level is large, or you are loading the transformer to more than 30 or 40% of its rated VA, you could run in to trouble. Monitor voltages and temperatures carefully (and have a fire extenguisher handy...)


What is the reason to use open circuit and short circuit methods to find Transformer losses?

The transformer can be tested on open and short circuit to find the iron losses and copper losses separately, which uses a fraction of the power than having to run the transformer on full-load.