S&C PMH Instructions For Operation Manual page 35

APPENDIX E — Continued
Recommended Voltage Ratings
In general, current-limiting fuses should have a maximum
voltage rating equal to, but not greater than 140% of, the
system line-to-line voltage since, for most applications,
the fuses can be exposed to full system line-to-line voltage
in clearing faults. Although there may be economic or
space-saving incentives for using current-limiting fuses
with voltage ratings "appropriate for system line-to-
ground voltage" (i.e., fuses with a voltage rating lower
than line-to-line voltage but greater than or equal to maxi-
mum system line-to-ground voltage), S&C can only recom-
mend such use in the following applications:
s
S&C ELECTRIC COMPANY
•
Protection of single-phase transformers serving single-
phase loads.
•
Protection of three-phase lateral circuits fed by single-
conductor shielded cable (provided each transformer
on that lateral is individually fused so that the current-
limiting fuse serving the lateral will not be required to
clear secondary faults).
•
Protection of single-phase lateral circuits fed by single-
conductor shielded cable where the load is line-to-
ground connected.
INSTRUCTION SHEET 663-503
Page 35 of 35
August 14, 1995