Engineering And Ordering; Engineering Information - ABB CPS6000 Product Manual

3 Engineering and Ordering

Engineering Information

Introduction
This section discusses the factors to be considered in determining the number of rectifiers and ringers
required in both non-redundant and redundant battery plants.
Rectifier Sizing (Non-Redundant Systems)
In non-redundant systems, the installed rectifier capacity of the battery plant must be sufficient to
provide the current required for the load during normal operations as well as the current required to
recharge the battery following ac power outages.
For the telecommunications industry, the system load current is known as the average busy- hour
current. (The average busy-hour current drain is defined as the average busy-hour current drain during
busy season with the plant operating at the normal voltage.) Therefore, the minimum installed rectifier
capacity (mirc) is the sum of the average busy-hour (abh) current and the required battery recharge
current, or
mirc = abh + recharge current
The battery recharge current is determined by two system considerations: the maximum time the
system is required to operate in the absence of ac power (reserve time), and the time allocated to
recharge the battery after ac power returns. These two times and Figure 3-1 may be used to determine
the recharge factor. This factor, when multiplied by the average busy- hour current, determines the
minimum installed rectifier capacity, or:
mirc = abh x recharge factor
The mirc divided by the individual rectifier capacity determines the number of rectifiers (of equal
capacity) required for a non-redundant system.
Rectifier Sizing (Redundant Systems)
In redundant systems, a spare on-line rectifier is included so that the loss of any one rectifier will not
cause the available plant capacity to fall below the required minimum installed rectifier capacity. Thus,
the loss of a rectifier will not affect the normal system operation nor will it cause the batteries to
discharge, and will allow the batteries to recharge in the required time.
In cases where the additional spare rectifier will provide the required battery recharge current, the mirc
satisfies the requirements for both non-redundant and redundant systems. In other cases, rectifiers in
addition to the redundant rectifier may be required to provide the battery recharge current. Typically,
the number of spare rectifiers required for a redundant system is the larger of one spare rectifier or
200% of the rated load.
Page 23
© Copyright 2021 ABB. All rights reserved.