A 1 0-A time-delay fuse is the maximum size permittee
to protect the 3-k VA transformer. Time-delay fuses an
used when the over current device is sized at less than
15 A.
The over current device protecting the primary of <
transformer is permitted to be sized as large as 2. 5(
(250%) times the primary full-load current, provided the
transformer secondary is also protected, Figure 14-25
The transformer secondary over current device is sized a
1.25 (125%) times the secondary full-load current. Th'
next size larger over current device is permitted exceple
where the secondary current is less than 9 A. In this case, the over current device is not permitted to be large
than 1. 67 (167%) times the transformer secondary circuit.