Transformer Loading

[aelec84]

Hello Forum,

Can you please assist with this scenario? Customer Owned transformer feeds 1200A, 4160V Gear. Metered load + 125% (220.87) and loads added/removed is less than 1200A on the gear. but what if if the kVA value of calculated load as described exceeds the transformer kVA capacity? Is that 125% applicable to transformer as well?

Thank you.

 

[jim dungar]

Hello Forum,

Can you please assist with this scenario? Customer Owned transformer feeds 1200A, 4160V Gear. Metered load + 125% (220.87) and loads added/removed is less than 1200A on the gear. but what if if the kVA value of calculated load as described exceeds the transformer kVA capacity? Is that 125% applicable to transformer as well?

Thank you.

Transformer loading is not covered by the NEC.
Transformer life is about heat and time (heat transfer).

If you can keep the heat, from load amps, down you can have the transformer in a hotter ambient. Conversely, if you can keep the heat down, from the ambient air, you can load your transformer more. If the transformer is allowed to cool down, it can handle higher loading for a short period of time.

Your transformer manufacturer should be able to help you, once you have developed a loading/time profile.

I remember installing a 3000kVA unit that had a continuous overload capacity of 150% when its cooling fans were working.

 

[Elect117]

In agreeance with Jim, the nameplate on the transformer can sometimes have an allowable overload percentage on it, which might help speed things up or ease concerns.

Just remember to oversize the secondary or primary accordingly. The transformer has oil/fans/ etc. to dissipate the heat, but the conductors do not.