Installation Manual Liebert Hipulse E Chapter 3 – Battery Installation
Single or '1+N' UPS System
(07/04) Page 3-3
3.4 Installation design considerations
Note:
Full safety instructions concerning the use and maintenance of UPS batteries are provided in the
appropriate battery manufacturers manuals. The battery safety information contained in this section
relates to key considerations which must be taken into account during the installation design process
and might affect the design outcome depending on localised conditions.
3.5 Battery Installation and Maintenance
3.5.1 Temperature considerations
Battery performance depends on the ambient battery temperature. Capacity and autonomy times are quoted for a new
battery operating at 20°C. Battery capacity is increased by 1% for every 1°C increase in temperature up to 25°C. If a
battery is used at temperatures above 25°C, its life is reduced; consequently its capacity and UPS autonomy time will
reduce more rapidly over a period of time. Operating below 20°C will reduce the battery capacity by approximately
1%-1.5% per 1°C. For example: if a battery discharge test is attempted during the middle of winter when the ambient
temperature is 5°C the battery capacity will be only 77.5% of its design value and will not satisfy its specified
autonomy time.
Ambient temperature, ventilation, spacing, float voltage and ripple current all affect the battery temperature. Uneven
temperature distribution through the battery string will cause the voltage distribution to be uneven which can also lead
to problems — it is therefore important to maintain a even temperature across the whole battery chain.
‘Valve-regulated’ cells are very sensitive to temperature and should be operated at a temperature between 15°C and
25°C. To help sustain this operating temperature range the battery is normally float charged at 2.25V/cell.
When batteries are mounted in the same room to the UPS module, it is the battery which dictates the designed
maximum ambient temperature, not the UPS. — i.e. in the case of ‘valve-regulated’ cells the ambient room temperature
should be kept between 15°C and 25°C, and not between 0°C and 40°C (which is the specified main equipment
operating temperature range). Temperature excursions are permissible for short periods of time provided the average
temperature does not exceed 25°C.
3.5.2 Battery population
The nominal DC bus voltage, and therefore battery float voltage, is set according the module’s rated input/output
voltage, and usually set to 432Vdc (380Vac), 446Vdc (400Vac) or 459V (415Vac). Given that the desired cell float
voltage is 2.25V, this means that a different number of cells are required in each case (see Chapter 5 - DC Intermediate
Circuit).
3.6 Battery protection
The battery is connected to the UPS through a circuit breaker which is manually closed and electronically tripped via
the UPS control circuitry. If the cells are rack -mounted (or located remote from the main UPS cabinet), this circuit
breaker, fitted within the cabinet, must be positioned as near as possible to the batteries themselves, and the power and
control cables connected to the UPS using the most direct route possible. The UPS electronic circuitry will trip the
circuit breaker if any of the following conditions occur:-
a) If the d.c. busbar drops below 330V d.c. (This would normally occur during a mains failure when the battery
autonomy time has been exceeded.
b) If there is a rectifier problem and the d.c. bus rises above (2.45 V/cell exceeded on the battery).
c) If the Emergency Stop is operated.
Note: All equipment servicing procedures should be carried out only by trained personnel.
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