SC300 Handbook
72
Copyright © 2007-2018 Eaton Corporation. All Rights Reserved.
IPN 997-00012-03 B2 Issue B2 July 2018
Parameter
Description
Where to find:
Only shown if an analog input is configured as
Battery Third Quarter Point.
Imbalance
The percentage imbalance of the
Mid-point
Voltage
, or the worst imbalance of the ¼ , mid
and ¾ point if QPM is in use.
Configuration
Set the following parameters.
Parameter
Description
Where to find:
String Fail alarm
parameters
See System Alarm Configuration on page
Web: Alarms > Alarm States
MPM Lockout
Period*
Time from when MPM is able to start until the
start of the
MPM Convergence Period
.
SC300: Battery > MPM >
Settings
Web: Batteries > Mid-point
Monitoring
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 / quarter 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 / quarter point
Imbalance
percent
threshold at the start of the
MPM Convergence
Period
.
MPM Stable
Threshold*
Mid-point / quarter 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
).
