1 Scope

The provisions of Clause 1 of UL 62368-1 apply, except as follows.

Replacement of text of the 1^st paragraph:

This outline addresses the safety of power distribution centers for information and communication technology equipment with a rated voltage not exceeding 600 V.

Power distribution centers which provide, distribute, monitor, and control isolated secondary circuit power to other equipment typically used in information and communication technology equipment installations (refer to Annex AA), and consist of some or all of the following:

– distribution panelboards, powerboards, disconnects, and overcurrent protective devices;

– control and monitoring equipment;

– assemblies consisting of racks, shelves, and enclosures which could contain any of the above components, interconnecting hardware, power supplies (such as rectifiers, converters, and inverters), batteries, and any other related peripheral devices.

The block diagram in displays, in single line form, a typical d.c. power distribution system. The rectifiers provide the power for the information and communication technology equipment loads and maintain the charge (float) in the batteries. The batteries and/or the backup generator provide the energy when interruption of commercial a.c. power occurs. The d.c. distribution system is to provide energy to the information and communication technology equipment loads with minimal power losses regardless of the state of commercial a.c. power. The d.c. power distribution system transmits the energy from the rectifiers or batteries to the information and communication technology equipment loads. Overcurrent protection devices may be provided within the distribution among the rectifier outputs, batteries, or the input to the primary distribution system. The rigid bus bar, which is typically used, is designed for a minimum voltage drop and is a distribution structure capable of withstanding fault currents.

The distribution system may be divided into primary and secondary distribution. The primary distribution system contains the overcurrent protection devices, the wire, and the cable to connect the output voltage from the batteries and rectifiers to the secondary distribution system. The overcurrent protection devices provide fault and isolation protection when a short or overload condition occurs on the wire or cable between the primary and secondary distribution systems. The secondary distribution system contains the overcurrent protection devices (such as fuses and circuit breakers), the wire, and cable to connect the output voltage from the rectifiers and the primary distribution system to the information and communication technology equipment loads. The overcurrent protection devices in the secondary distribution system are intended to protect the wire and cable from faults in the secondary distribution system. Equipment faults are normally protected by overcurrent protection devices either within the frames containing the information and communication technology equipment loads or within the

D.C. SECONDARY DISTRIBUTION

Addition of text to the bottom of Clause 1 of UL 62368-1:

This outline does not apply to the following:

– power units other than Class 2 covered by the Standard for Power Units Other Than Class 2, UL 1012, and General Use Power Supplies, CSA C22.2 No. 107.1;

– Class 2 power units covered by the Standard for Class 2 Power Units, UL 1310, and Power supplies with extra-low-voltage class 2 outputs, CSA C22.2 No. 223;

– Telecommunication technology equipment covered by the Standard for Audio/Video, Information and Communication Technology Equipment Safety – Part 1: General Requirements, UL 62368-1; and

– Uninterruptible power supply equipment (d.c. to a.c. inverters) covered by the Standard for Uninterruptible Power Systems, UL 1778, and Uninterruptible Power Systems, CSA C22.2 No. 107.3.