16 |
P a g e
OVR-15, 27 & 38 LV cabinet Instruction Manual
4.2.5
Rechargeable Batteries
The LV unit is supplied with two 12 V batteries connected in series and securely mounted in the LV
cabinet for providing back up power to recloser in case of external auxiliary power failure. The batteries
are protected by separate MCB.
Typically, the battery bank ensures minimal stand-by back up for 24 hours at 20 °C from a fully charged
initial condition. However, the actual backup duration depends upon various site conditions such as:
-
Ambient temperature & initial condition of the battery (temperature & storage period before
commissioning, periodic charge/discharge, battery maintenance)
-
Frequency of external auxiliary power outages & duration of each outage (i.e. the number of
charging/discharging cycles) and depth of each discharge.
-
Percent charging (terminal voltage) of the battery at the time of outage of external auxiliary power.
For additional details it is recommended to refer battery manufacturer documentation. Please also refer
the section “Inspection & Maintenance” of this manual.
A battery temperature sensor is provided near the battery bank terminals. Battery Charging temperature
range is -20 + 50°C.
We are providing Valve Regulated Lead Acid (VRLA) batteries which are temperature & charging voltage
sensitive. Although maintenance by way of water topping up is not required, regular checking and
assurance of proper charging voltage, depth of discharge and operating temperature is needed.
In case of loss of external auxiliary supply, the intelligent battery charger switches over to battery bank
for power and continues to conduct its function. Recloser will work as long as the battery bank voltage
remains above 20.5V. Below 20.5 V load management algorithm activates within intelligent battery
charger and disconnects the power feed to ACM, RER615 and optional radio modem. This is done to
prolong the batteries going into deep discharge mode. With relay not being powered, the recloser will
not be able to perform any operation.
-
Due to frequent and long duration external power outages, battery frequently undergoes
discharge and charge cycles. This reduces battery capacity, charging efficiency & overall
service life.
-
During consistent long duration outage, the battery bank voltage may drop below 18V (9V
per battery) indicating battery might have deep discharged & now cannot be charged
again. At this point, the battery needs complete replacement by a brand new, fully charged
equivalent battery.
-
Connection of any additional load to battery is strictly prohibited, and ABB will not be liable
for any adverse impact it can create to recloser performance including life of battery.
-
Handling reclosers during long outages
1.
If battery bank is healthy and in fully charge condition i.e.
≥
24 Vdc, for the power outage
can be of < 24Hrs. without any special attention required.
2.
If power outage is for more than 24 Hrs OR typically > 10 CO operations after power
failure, then it is considered as long power outage requiring special attention of
batteries.
3.
During long outages, the batteries might get drained to such a level that it might go into
deep discharge stage i.e. battery bank voltage goes below 18 V.
4.
In this situation recloser will not be able to recharge the batteries automatically and
external charging may be required. Such situation might also damage batteries
permanently and thus required to be replaced.
5.
To avoid such situation, in case of power outage is expected to be more than 24 Hrs.
switch OFF the battery MCB in the beginning of the outage and when the power resumes,
switch it back to ON.
6.
If power outage is more than a month, then charge the batteries on regular interval
externally to ensure the battery bank voltage is always more than 21 VDC.
Caution
