TRANSFORMERS

[t-rhea]

Using the table 450-3B to fuse a CPT, where the CPT is under 600 volts. Can I fuse the primary side using the Primary only 125%-167%-300% respectively and also fuse the secondary side using the Primary and secondary protection values 125%-167% respectively?
I believe this to ok due to the primary only needs protection?

 

[jim dungar]

Re: TRANSFORMERS

Control power transformer primary protection is almost always required. Secondary protection is usually optional but sometimes is required, 430.72(C) and 450.3.

If secondary protection (125% max.) is provided then the primary protection may be increased in size, table 450.3(B).