Search results for query: *

Jraef, that was very helpful thank you. I wanted to collect more information before i make a post. It makes sense that contractors are faster than breakers, but if I understand you correctly, that only applies to electrically held contractors right? The plan is to use MCC to feed a transformer...

Thanks everyone. I have been told that a LV MCC can have an input breaker. If that's correct, I believe we can have the same level of transformer protection, right?

Thanks everyone. Zogzog, I still don't understand why we will have arcflash issues with feeding MCCs Vs Switchgears. We can have similar arcflash relaying on both systems, right? Also, for larger LV loads (like over 100 HP), is there advantage of using switchgear breakers instead of regular MCC?

We're looking into upgrading our system. Can we use MV MCCs to feed transformers, or do feeders have to be switchgears? What is prefered and why? Also, can I have transformers feeding LV MCCs directly, and not have to go though a LV switchgear? Is the a specific size HP for LV motors before it's...

Thanks everyone. The Transformer is actually a 2-winding one. Based on cranky108's answer, the 28MVA rating is for both windings, and since the prinmary winding sees seconday load plus transformer loss, it should get more attention.

Thanks burnt2x. I actually forgot to mention that the voltage and current values I had were from e-tap load flow study (not rated values). The transformer is rated for 28MVA with class FA/FA, and temp rise 65 deg. Thanks!

Scotty, actually the client shared an e-tap model showing the following: Primary side: 72KV 162.2A Seconday side: 4.092Kv 2693.4A I looked some formulas online (for 3 phase systems), and calculated Primary and Secondary MVA as I mentioned above. Did I make a mistake in calculation? If not, is...

Thanks guys. Actually, the secondary MVA was found to be 19.067MVA, while primary side was 20.204MVA. That's about 5.6% loss. Which value should I compare to the transformer rating?

I'm not an electrical engineer, but looking into a transformer issue. Does MVA rating refer to primary or secondary side of transformer? I know there should be some losses through windings. Thanks!