Transformer protection

[ashbeel6]

I am working on a circuit design for a 3 Phase balanced load of 35A at 600 VAC. A 150 KVA transformer and 100A fuse disconnect switch (FDS) panel with 40A overload relay is available as spare. I want to make use of both 150 KVA transformer and aforementioned fuse disconnect switch instead of buying additional equipment. Here is how I intend to proceed.

1. Use 150 KVA transformer with 100A fuse disconnect
switch and fuse it at 60A [based on existing load of 35A] sizing the conductor accordingly. Instead of transformer current rating.
2. Transformer secondary to be protected by a 125% FDS.
3. Remove overload relay

Comments/ concerns, suggestion are highly appreciated.

 

[busbar]

Is 600V on the high or low side of the transformer? What is the other side's voltage and grounding?

Are the 60A fuses on the high or low side of the transformer?

 

[alehman]

If the 60A fuses are on the primary side, make sure they are adequate to withstand the transformer inrush. Typicallay fuses must be sized roughly 125% or higher of primary full load amps in order not to open due to inrush current (exact size depends on the actual fuse used).