Vertiv™ NetSure™ Control Unit (NCU) User Manual
- The battery voltage drops below the preset End Test Voltage (Vend) (see Figure 1.4). The battery has not passed the
test and the test is interrupted. A bad battery alarm is activated.
- If a critical alarm occurs during the test or there’s not enough load, the battery test is aborted. In such cases a “Battery
Test Fail” alarm will be activated (indicating the test couldn’t be done). This alarm is different from the “Bad Battery”
alarm (meaning the test was completed but the battery didn’t pass it).
• A battery test alarm is active during a battery discharge test.
• If the battery has not passed the test, a bad battery alarm is activated.
• After the battery discharge test, the output voltage of the rectifiers increases so that the rectifiers supply the system and
charge the batteries.
NOTE!
A procedure for performing a manual battery discharge test is provided on page 47.
Battery LVD (Low Voltage Disconnect)
To prevent serious damage to the batteries during a commercial AC power failure, the batteries can be disconnected by voltage or
time control.
The batteries are reconnected automatically when commercial AC power is restored and a predetermined DC voltage level is reached.
See “LVD Tab Programmable Parameter Descriptions” on page 151 for descriptions of programmable LVD parameters.
Battery Capacity Prediction
The NCU can predict battery capacity. When a battery is connected to the system at initial setup or increasing the number of
batteries, you need to update the Battery Ah rating. After doing this and making sure the battery is fully charged you need to reset
the battery capacity used percentage by performing the “Reset Battery Capacity” command to tell the NCU that the batteries are
100% charged. From this point forward the NCU will keep track of the battery current and time to predict the battery capacity used.
Battery Block and Battery Midpoint Monitoring
The NCU can monitor battery blocks (12 V blocks) or midpoint battery voltage of battery strings connected to the EIB (Controller
Extended Interface Board) assembly. An alarm is issued when either battery block voltage or battery midpoint voltage is abnormal.
Thermal Runaway Detection and Management
Functional Description:
The system uses several control mechanisms to avoid thermal runaway.
• During a short high rate discharge, the batteries will normally get hot. The NCU takes this into consideration. After
completion of the discharge duty, the batteries are recharged with a limited current to avoid heating the batteries any further.
• The temperature of the batteries can be monitored, and the NCU sets the charge voltage appropriately, as previously
described under “Battery Charge Temperature Compensation” on page 4.
• In addition to battery temperature compensation, if battery temperature rises above a set temperature limit, the system stops
battery charging completely by lowering the output voltage to the “BTRM Voltage” setting. This allows the batteries to cool
down. The system also provides alarm notification of this occurrence. Power supplied to customer equipment is not
interrupted. See “Setting Battery Thermal Runaway Management (BTRM) Feature” on page 40 for programming.
• The battery LVD circuits can be programmed to open (disconnect) if a high temperature event occurs (HTD-High
Temperature Disconnect). The contactor(s) open when battery temperature rises above a programmable value and close
again when battery temperature falls below another programmable value. See “LVD Tab Programmable Parameter
Descriptions” on page 151 for programming.
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