Tyco Electronics Galaxy SC Controller J85501F-1
Issue 13 February 2001 Feature Descriptions 7 - 24
Where,
ΣC
Ron
= sum of ampacities of all rectifiers turned on
and
ΣI
Ron
= sum of outputs of all rectifiers turned on
The energy-management algorithm compares the plant load current
(I
Load
) with the sum of output currents being delivered by all rectifiers
presently connected and turned on (ΣI
Ron
). The controller then
multiplies the larger of these two values by 1.04 and shuts down
unneeded rectifiers to just meet the terms of the inequality of the
equation with the sum of the ampacities of the remaining rectifiers that
are left running. In this manner, the larger, more-efficient rectifiers are
allowed to remain running at or near maximum load, where individual
efficiencies are highest. But unneeded rectifiers are not neglected,
either. To ensure that all rectifiers are operational when eventually
called upon for service, the algorithm exercises all rectifiers on a
monthly basis, guaranteeing that every connected rectifier is operated
for at least 24 hours each month. All connected rectifiers that have not
operated a total of 24 hours in the previous monthly cycle will turn on
the first Wednesday of the next month at 10:00am for 24 hours.
Needless turning off of rectifiers due to short-term swings in plant load
are eliminated by restricting the shutdown of rectifiers to 10-minute
intervals. After initially powering up a Galaxy SC controlled battery
plant, the unneeded rectifiers are shut down one at a time, at 10-minute
intervals. The smallest ampacity rectifiers are turned off first, leaving
the minimum number of larger ampacity rectifiers on. On the other
hand, sudden large increases in plant loads will immediately be
accompanied by a rectifier being turned on. During the 10-second
rectifier walk-in (gradual warm-up), the BD (battery on Discharge)
alarm is inhibited to prevent nuisance alarms. To reduce turn-on/turn-off
stress on any rectifier, no rectifier is permitted more than three on-off
cycles per day by the energy management routine. Rectifiers in standby
mode (through their front panel switch control) will not be turned on by
the energy management algorithm. The energy management routing
uses a hardware and software DIP switch to disable the algorithm. The
algorithm is also disabled when either a Battery on Discharge (BD)
alarm occurs, the rectifiers are boost charging batteries, attached
rectifiers are not configured in the system, or attached rectifiers do not
provide a VI or shunt signal compatible with the associated rectifier
interface board. If the energy management algorithm is DIP switch
enabled and then disabled due to a BD condition, the controller
generates the Efficiency Disabled warning.
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