GE Industrial Solutions Galaxy Vector Rack Mounted Controller J85501M-1 - Manual (Page 40)

Galaxy Rack-Mounted Vector Controller J85501M-1
3 - 12 Operation Issue 2 January 2008
Enhanced VR (Valve regulated) battery floats at 2.27 VPC, if
Battery Thermal Compensation is enabled or 2.25 VPC if used
without Battery Thermal Compensation. A 12 cell, 24V plant
using this battery would have a desired FSP of 2.27 x 12 =
27.24V with or 2.25 x 12 = 27.00V without Battery Thermal
compensation.
Rectifier Current Limit in Float mode (FCL) is an adjustable
configuration parameter from 30% to 110% of rectifier capacity.
This parameter can be important in limiting the recharge current
available following a deep discharge in a plant using a “sealed”
or valve-regulated battery type to a level which is safe for that
battery and not cause unnecessary internal pressure buildup and
venting. Typically, this maximum safe recharge rate for “sealed”
or valve-regulated battery types in the industry is in the range of
1/10 of the 8 or 10 hour rating. Refer to your specific battery
manufacturer for recommendations regarding the battery type
used. The following typical example shows the use of the FCL
feature to maintain the maximum recharge rate decided upon.
Consider a plant with three strings of 2VR375E Lineage Power
KS23619 Enhanced VR Series batteries, four 100A rectifiers
and a 200 amp typical load. When ac power returns following a
significant discharge, 200 amps are available for recharging
these batteries, a rate of 67A per string (200A / 3 strings).
Recharge should be limited to approximately 40A per string
(1/10 of 375) however, reducing the possibility of venting and
life depreciation of the batteries. Calculate current limit for
limiting recharge to 40A per string as follows:
CL = [Plant Load + (Max Recharge per String × # Strings) /
(Rect Cap × # Rect) ] × 100
CL = [ 200 + (40 Ч 3) / (100 Ч 4)] Ч 100
CL = [(200 + 120) / 400] × 100
CL = (320 / 400) × 100 = 80%
Check for N + 1 redundancy with this CL value with the
following statement:
Plant Load < [Rect Cap × (# Rect - 1) × CL] / 100
200 < [100 Ч (4 -1) Ч 80] / 100