Transformer Load

You should know how to do this if you are taking on these kind of projects. You are limited by

1. Your source capacity

2. 15 kv cable ampacity

3. Voltage drop

4. overcurrent coordination

5. Other unknowns at this time.

Dear Mr.Mosquito,

Your thread will make more sense if you have used the word Step-up

than elevator. A s I could make out - you want to step up to 15 kv level , transmit

and utilise the same at some other location.

1000 kva transformer will have primary FLC- 1313 A & at 0.9 pf it will be

1181A. The FLC at 15 Kv level will be 38.49 A & at 0.9 pf it will be 34.64 A. You can

draw a total of 34.64 A from the Secondary of 1000 Kva Tr. You can connect 5 nos

of trs but see you do not exceed the amperage. If they are identical each can be

179.99 Kva each { (34.64 /5) x 1.732 x[15000 / 1000 ]= 179.99 Kva.

As already pointed by one of the members , some factors and pre-

cautions are to be taken out.

( Any thing is not small for this mosquito atleast)

Manroop.Chennai.

Thanks y´all! I will go from there! Mosquito

Never heard of an elevator before, but the facts provided indicate it is a step-up tx. Just atop of the head answer would suggest 4 units will do the job. But have you considered the cost of cable alone? You dont state distances apart from step- up tx.

PS. On edit i see "manroop" have done the calcs already. Enough reason to GA you

Mosquito, u did not tell us the capacity of the other 15KV transformers u intend to power from the 1MVA existing transformer.

So far, the First responder to ur question is very correct.

Dickson.

Mosquito, u did not tell us the capacity of the other 15KV transformers u intend to power from the 1MVA existing transformer.

So far, the First responder to ur question is very correct.

Dickson.

Dear Mr. Dickson,

Well I am planning to feed actually 5 transformers this point in time:

1) one 400 kva, 15kv, 400 v, 50 hz

2)one 160 kva, 15kv, 400 v, 50 hz.

3) one 100 kva, 15kv, 50 hz.

4) 50 kva, 15kv, 400 v, 50hz.

5) 250 kva, 15kv, 400v, 50 hz.

Thanks, Mosquito

Whereas the answer from Monroop is significant, I shall add to it the following;

1-you have to regulate the primary voltage of the main step up transformer to be stable at 415 Volts, other wise you will get a lot of distrubance in voltage on 15 KV side. You must be conversent with the transformation ratio equation.

2- You have to consider the ampicity of primary and secondary sides of the stepup transformer for downstream distribution capacity.

1-you have to regulate the primary voltage of the main step up transformer to be stable at 415 Volts, other wise you will get a lot of distrubance in voltage on 15 KV side. You must be conversent with the transformation ratio equation.

I think the voltage is stable we are going to have a generator feeding this 1000 KVA transformer. Why do you want it at 415v, and what kind of disturbances are we gonna get on the 15 kv side? Mosquito

As rule of thumb, the principles of transformer ties to conservation of energy ( first law of thermodynamic), where the total power input to transformer(primary winding) is equal to power output of transformer(secondary winding), assuming close system.

However, power factor taken into consideration to represent the energy loss due to heat and others inherant magnetism.

For the First step up transformer.

The step up transformer, transform the high voltage(with existing current rating) to lower voltage ( resulting current amplified to the ratio equal to step down ratio of voltage, according to Ohms law)

For the subsequent distribution to the others transformers/ Load.

This resulting amplified current will be split into 5 portions, considering the connection in series, for subsequent distribution to respective transformers(qty =5).

After determine the real power, = KVA times power factor (p.f)

This real power will be share among the five transformers, in which the distribution connected in series, create load where the current will be split into 5 portions (for 5 transformers), while the voltage is maintained. ( in this case is 15KV, as feeding source from previous device.)

Practically, the system can feed as many transformers, but there's always a trade off. Subsequent distribution, the current will be divided according to series connection and will be lower ( while 15KV voltage is maintained) for each transformers, resulting each of transformer(same capacity) will have a input power of 1/5 of feeding power to it ( P = Voltage(V) x Current (I) )

P= 15KV x resulting current in series connection.

Hope that this will shade some light on topic. thanks

To correct my mistake:-

The first transformer that mosquito mentioned is actually termed as step down transformer. ( as refer to input voltage transform to lower output voltage).

thanks.

Primary coil 400V

to

Secondary coil ; 15KV

To supersede the above statement, this first transformer is a step-up transformer.

What is the intended output voltage of the other transformers?And why do you wish to step up to 15KV, to be applied to the primary of other transformers?Would it not be simpler to generate the desired output in a single step? I now what you wish to do, and the other answers are correct, but I don't understand why.

15KV level introduces many extra costs because of the insulation expense, terminations(High Pot),wiring costs, etc.

Are you going to step the voltage back down at the other end?

If so, there are better ways to achieve the same result.

What is the intended output voltage of the other transformers?And why do you wish to step up to 15KV, to be applied to the primary of other transformers?Would it not be simpler to generate the desired output in a single step? I now what you wish to do, and the other answers are correct, but I don't understand why.

15KV level introduces many extra costs because of the insulation expense, terminations(High Pot),wiring costs, etc.

Are you going to step the voltage back down at the other end?

If so, there are better ways to achieve the same result.

Yes the others transformers will receive 15 kv on the primary and step down to LV 400 v. Each one of the step down transformers are around 500 meters from the main step up transformer(1000KVA)

Possible. If......

Capacity of 1st transformer = sum of capacities of other 5 (factoring in efficiencies)

Is this some sort of distribution network that you r setting up ?

Please clarify