Fusing of Capacitors, Power Distribution Delivery

Common Systems Connection Standards	AT&T Services, Inc
Date: August 31, 2007	ATT-TP-76450, Issue 9

2.5Fusing of Capacitors

Equipment incorporating the use of power distribution apparatus which uses capacitors shall be fused to protect the power distribution bus from a shorted capacitor. Fuse and protection information must be provided in the supplier's response documentation to be in compliance with this item. The equipment manufacturer shall provide a label indicating equipment capacitors must be pre-charged prior to power up the equipment.

2.6POWER DISTRIBUTION DELIVERY

All power distribution products must meet the requirements listed in Section 1 of this document.

AT&T approved Power Distribution Units (PDU) shall be used to power transport and data equipment. Power is distributed to the NE from Battery Distribution Fuse Bays (BDFB) or an arrangement utilizing a Secondary Power Distribution Unit (SPDU). The SPDU is smaller than a BDFB in physical size and capacity. Direct feeds to the NE from the BDFB will be considered on a case by case basis when required. NE will not be directly fed from Power Board Distribution. Contact the AT&T Common Systems Power Technical Staff when requesting direct BDFB feed.

PDUs that are independent of the network element but included as part of the total package must meet the requirements listed in this section; must be approved for use, and should be identified by an associated AT&T PID (Product ID) number assigned by the AT&T Power Technical Staff

All approved PDUs shall be equipped with at least one of these forms of overprotection devices, (1) GMT Fuses, (2) Telpower® Fuses, (3) Telecom TLS Fuses, (4) DC Rated Circuit Breakers. (note: circuit breakers in PDUs shall only be fed by circuit breakers).The recommended form of DC power distribution is GMT fuses, Telpower® fuses, Telecom TLS Fuses, or Circuit Breakers, in that order. The size of the DC requirement will serve as the primary qualifier, but fuses are the preferred method of over-current protection.

•GMT Fuses – Generally sized to accommodate 0.18 – 20 amp requirements. List 2X demand should not exceed 80% rated fuse size.

Telpower® Fuses – Exclusively produced by Cooper-Bussmann, these fuses are available in sizes from 3 amps to 600 amps, packaged in Blue to signify DC only. Telpower® fuses are also available in various styles for different needs. Some of the approved styles commonly seen are TPA, TPL, TPS and TPN. All Telpower® fuses should be sized at 125% of List 2X load (List 2X load not greater than 80% of their fuse faceplate rating).

•Telecom TLS Series Power Fuses – Exclusively manufactured by Littelfuse shall be used in the 80-125A sizes with the Canadian Shunt TFD101-011-01 fuse disconnect/fuse holder. Littelfuse TLS fuses should be sized at 125% of List 2X load (List 2X load not greater than 80% of their fuse faceplate rating).

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