Individually Mounted PDU, Direct Bdfb Power Delivery

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

Circuit Breakers - Only thermal magnetic and magnetic type DC circuit breakers are acceptable. Circuit breakers should adhere to all applicable UL and ANSI standards. DC Circuit breakers that are labeled 100% are full load rated and may be sized at the same capacity as the List 2X drain.

•NOTE: Due to the circuit protection strategy deployment found in AT&T companies, the use of circuit breakers placed in the power architecture should be avoided when a fuse provides the next step of protection (generally found at the BDFB). It is recommended that circuit breakers be protected by circuit breakers, fuses with fuses or fuses protected by circuit breakers. The use of circuit breakers placed in the embedded power distribution units found in network elements should be avoided. The preferred method of circuit protection at this level is fuses.

2.6.1All fuses and circuit breakers shall meet Quality Level III as defined by Telcordia SR-332.

2.6.2Filtered Battery

All Network Elements requiring “Filtered Battery” shall provide the filtering within the Network Element. (Filtered DC power PDUs are not provided by AT&T to remove excessive levels of transient noise generated within the Network Element).

2.7Individually Mounted PDU

Even though not recommended as a choice by AT&T, some Network Elements designed by various manufacturers require specific PDUs that include unique characteristics needed to serve their specific network device. These “special PDUs” must meet all the same design criteria identified in this document as well as the ATT-TP-76200 NEBS publication. If accepted, this “special PDU” would be listed as part of the Network Element approval, purely as an integral part of the package and its approval is exclusive to the associated network element. Furthermore, this “special PDU” should be reviewed by the Common Systems Technical Staff to insure its integrity.

2.8NE Integrated Power Distribution

Defined as; power distribution that is integrated within the framework of the network element (e.g. #5 ESS PDF frame). Generally speaking, NEs requiring more that 200 amps of DC power need this type of power distribution. The NEs are commonly found in large multiple interrelated- bays.

These type devices are considered equipment specific and should meet the requirements as listed in Section 1 of this document as well as the ATT-TP-76200 NEBS publication. Additionally, AT&T recommends the use of fuses in lieu of breakers in these applications.

2.9Direct BDFB Power Delivery

Page 10