Sun Microsystems Netra t1 100, User And Administration Manual

Page: 35 / 154

Chapter 3 Using DC Power 13
Overcurrent Protection Requirements
■
Overcurrent protection devices must be provided as part of each host equipment
rack.
■
The supply source must be electrically isolated from any AC source or other
voltages by double or reinforced insulation.
■
Circuit breakers meeting the requirements shown in
TABLE 3-1
must be fitted
between the DC source and the Netra t1, and they must be ON when in the UP
position.
Note – Overcurrent devices must meet applicable national and local electrical safety
codes and be approved for the intended application.
TABLE 3-1
Overcurrent Protection Requirements
Description
Requirement
Current rating 7.5A maximum
Voltage Maximum 60 VDC rated in –48 VDC power systems
Maximum 75 VDC rated in –60 VDC power systems
Type Fast trip
Protection EITHER:
Double pole breaking (both grounded and ungrounded conductor
to open on fault)
OR:
Single pole breaking ungrounded conductor (–48V) to open on
fault.
Contact gap Minimum 3 mm
Nuisance tripping Circuit breaker must not operate when presented with an in-rush
current of 27 amps and a duration of 2.5 microseconds
Quantity One per feed, up to 2 per system
SysAdmin.book Page 13 Friday, March 30, 2001 2:38 PM