Chapter 3
System Operation
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IPN 997-00012-03 B2 Issue B2 July 2018
45
Load Based Rectifier Shutdown
Redundancy
= N
If redundancy is set to N and no batteries are connected, plus the alternative
energy source is not producing enough power, then there is a risk of the system
load being dropped. Do not set
Redundancy
to N at mission-critical sites.
Load Based Rectifier Shutdown is not available with APR48-3G (prior to PR5), EPR48-3G,
APR24-3G and CR48-3G rectifiers.
If Load Based Rectifier Shutdown (LBRS) is enabled by setting
Shutdown
to
Automatic
then the
SC300 automatically shuts down rectifiers when the total load current is significantly less than the
total rectifier capacity.
This raises the average load on the remaining rectifiers which will then operate at a higher
efficiency. This results in a decrease in system power consumption.
The SC300 shuts down APR48-3G PR5 rectifiers before the more efficient APR48-ES and NPR48-ES
rectifiers.
The run time of all rectifiers is recorded and the usage within each group of rectifiers is balanced to
ensure even aging.
The SC300 will progressively restart rectifiers if the load increases.
The number of rectifiers left running by LBRS depends on the
Redundancy
setting:
•
N Plus 2: Two spare rectifiers are always running. Three or more rectifiers are always
running.
•
N Plus 1: One spare rectifier is always running. Two or more rectifiers are always
running.
•
N: If an alternative energy source is powering the load, then all rectifiers can be shut
down. Otherwise at least one rectifier is always running. There is no redundant rectifier.
Rectifiers shut down by LBRS will have the yellow LED on.
The SC300 will automatically restart all rectifiers if ac supply has failed, or more than one
rectifier has failed, or Battery Test / Equalize / Fast Charge are active, or the bus voltage is below
the Low Load threshold.
In a three phase system with phase detection, LBRS will shut down rectifiers in such a way as to
keep a similar number of rectifiers on each phase.
► To enable Load Based Rectifier Shutdown
•
Use the SC300 keypad to go to:
Rectifiers
>
Settings (tab
) > set
Rectifier Shutdown
to
Automatic
.
•
Or, in DCTools/Web go to:
Rectifiers
> set
Shutdown
to
Automatic
.
Ensure that Rectifier Start Up Delay is less than 30 seconds. See information on page 42. LBRS
will not function correctly if the start-up delay is more than 30 seconds.
