IEEE 946-2020 pdf free download

IEEE 946-2020 pdf free download.IEEE Recommended Practice for the Design of DC Power Systems for Stationary Applications.
6.2.3 Telecommunication
For traditional telecommunications sites, a minimum of 3 h to 4 h of battery backup is typically provided for sites with permanent on-site. auto-stan, and auto-transfer standby engine-alternators. A minimum of 8 h is typically provided tbr sites not served by a standby engine-alternator. In order to maintain the battery backup for the most critical loads, non-critical loads are sometimes shed.
The battery is generally sized based on a constant load current during a predefIned period of time. However, if the load is constant power type in which the current rises as the battery voltage drops, then this increased current has to be considered in the battery sizing. Typical nominal dc bus voltages are +12 V. +24 V. —48 V, 380 V. and 575 V.
In general, there may he regulatory rules or guidelines that determine the amount of backup time for traditional voice service. The most common of these rules requires a minimum of 8 h of battery backup for sites not backed up by an on-site permanent auto-start, auto-transfer engine-alternator. For sites with a permanent on- site auto-start, auto-transfer engine alternator, the rule is typically 3 h of battery backup plus travel time to the site, or simply a straight minimum of 4 h of battery backup. Non-voice loads (such as broadband data and video) may be shed in some sites after a certain period of time, or after a certain voltage is reached in the discharge in order to extend the operation of more essential loads. Typically, this time could range from 5 mm to several hours and is company specific. When this is done, it is typically done off of a timer activated by a commercial ac failure or “battery on discharge” alanm or the timer starts when a certain discharge voltage is reached.
Most telecommunication dc power systems (commonly known in the telecom industry as a “de plant”) designed for three or more hours of battery reserve use a battery designed tbr long-duration discharge. If the site is powered by renewable energy or has poor grid quality, a battery designed for cycling duty should be considered.
6.3 Installation design
The design of each battery installation. signage, battery room design, and access (when applicable) should be in accordance with the appropriate IEEE standards and local codes. IEEE 946-2020 pdf free download.