Determining if a Three Phase Transformer Bank is Overloaded using Load Readings

t_n_k

Joined Mar 6, 2009
5,455
On a less important matter this thread would be better placed in General Electronics Chat Forum rather than the Projects Forum. There doesn't seem to be any reference to a specific 'project' in this instance.
 
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GetDeviceInfo

Joined Jun 7, 2009
2,125
should probably flush out the 'white' wire thing as well. In North America the standard phase colors are Red/Black/Blue. White is reserved for the neutral and extensions of it. Just for your future reference.
 

t_n_k

Joined Mar 6, 2009
5,455
should probably flush out the 'white' wire thing as well. In North America the standard phase colors are Red/Black/Blue. White is reserved for the neutral and extensions of it. Just for your future reference.
Good point.

Probably should dispense with colors altogether since the usage varies from country to country. Where I live black (along with blue) is reserved for neutral, for instance.
 

Thread Starter

Novice Powers

Joined Feb 26, 2012
8
is it ok to say my voltages will not be balanced if my load is not balanced? for example if the load is customers/residents on a utility company's distribution system

And if that is the case can i use the equations for a balanced system as an approximation to the actual load on the bank? (that is avoiding the symmetrical component calculations)

And finally can i simply calculate the loads on the three single phase transformers separately and add them to get the total load the bank is doing and then just compare that total the total rated capacity of the bank to determine overloading?

Please be as pedantic as possible, I fully understand that the VA rating is only relevant with respect to rated voltage, i never thought about that before but the consequences of making the mistake and thinking otherwise is explosively clear.

Thanks a lot guys for your responses, it helped, and you gave me a lot on which i can do further reading.
 

GetDeviceInfo

Joined Jun 7, 2009
2,125
is it ok to say my voltages will not be balanced if my load is not balanced? for example if the load is customers/residents on a utility company's distribution system
the neutral will keep the voltages balanced.

And if that is the case can i use the equations for a balanced system as an approximation to the actual load on the bank? (that is avoiding the symmetrical component calculations)
Not in that example. Even though on the design side you use standard wattage calculations, the actual loads are independant and should be measured to determine actual loading.

And finally can i simply calculate the loads on the three single phase transformers separately and add them to get the total load the bank is doing and then just compare that total the total rated capacity of the bank to determine overloading?
Yes to adding them, however you did indicate a transformer grouping that had different KVA ratings, and as such, the total KVA does not properly describe the configuration. If the total came to say 150KVA, but you where drawing the bulk of that on one leg, then you've greatly exceeded any one bank.

Generally, you would simply add the legs together for total power. A balanced system offers the simplicity of calculating based on line values.
 
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