Eaton SC200 - Battery Time Remaining

System Operation
Copyright © 2007-2011 Eaton Corporation. All Rights Reserved.
IPN 997-00012-50H November 2011
59
Configuration
Set the following parameters.
Parameter
Description
Where to find:
String Fail alarm
parameters
See System Alarm Configuration on page 46.
DCTools/Web: Alarms >
Alarm States
MPM Enable
Enable/disable Mid-point Monitoring.
SC200: Battery > MPM >
Settings
DCTools/Web: Batteries >
Mid-point Monitoring
MPM Lockout
Period*
Time from when MPM is able to start until the
start of the MPM Convergence Period.
MPM Convergence
Period*
Time from the end of the MPM Lockout Period
until MPM State is Stable. During this period the
Current MPM Threshold is calculated using linear
interpolation between Start Threshold and Stable
Threshold and the MPM State is defined as
Converging. After this period the MPM State is
defined as Stable and the MPM Stable Threshold
applies.
String Fail
Recognition Period
If the mid-point Imbalance percent of a battery
string exceeds the MPM Threshold for this period
of time the String State is set to Fail and the String
Fail alarm is activated.
MPM Start
Threshold*
Mid-point Imbalance percent threshold at the
start of the MPM Convergence Period.
MPM Stable
Threshold*
Mid-point Imbalance percent threshold after the
convergence period.
* A dynamic alarm threshold is used to give the best possible battery fault detection:
1 After the end of a discharge, Fast Charge or Equalize cycle, MPM does not start until the
end of the MPM Lockout Period, to ensure the system is in float charge.
2 At this point, the battery cell voltages are expected to be widely spread, so the alarm
threshold is set high (MPM Start Threshold).
3 The alarm threshold is then progressively reduced over the MPM Convergence Period.
4 After the end of the MPM Convergence Period, cell imbalance is assumed to be stable, and a
fixed threshold is used (MPM Stable Threshold).
Battery Time Remaining
The SC200 obtains characterization data from every full battery discharge, to a specified end
voltage.
During a battery discharge, the SC200 uses this characterization data to calculate an estimated
time until the battery will reach the specified end voltage.
 If a battery disconnect LVD is fitted then the end voltage will usually be the voltage at which the
LVD disconnects the battery.
 Battery Time Remaining is designed for a constant power load. The accuracy of the time
remaining calculation will be reduced if the dc power system is connected to a predominantly
resistive (constant current) load.
 The time remaining calculation will not be correct if a non-essential load is disconnected during
the battery discharge.