Thales 421, Эксплуатация и обслуживание, Страница: 154 / 256

LLZ 421
Maintenance Operation and Maintenance
ILS 420
6−12
Ed. 01.10 SOAC
6.3.3 Matching the charging Voltage of BCPS Modules
6.3.3.1 Reasons for Voltage matching
The BCPS has a fixed voltage of 54 V±3 % for parallel operation with lead batteries. It is not possible
to vary the output voltage for operation with other types of battery, e.g. nickel cadmium batteries. An
adjustment of ±1 V is however possible on the front panel of the slide in units. This is intended for
optimization of the trickle charge. The most important parameter for operation of lead batteries at the
BCPS is the trickle charge voltage. This voltage is 2.23 V/cell ±1% in accordance with VDE (registered
society of German electrical engineers).
In the interests of optimizing the charge Thales have utilized the upper tolerance limits and fixed the
trickle charge voltage at 2.25 V/cell. This results in a trickle charge voltage of 54 V for a battery with
a rated voltage of 48 V. Strictly speaking however this fixed trickle charge value of 54 V is only valid
at a temperature of 20 °C in the battery compartment. If the temperature rises above 20 °C, it is neces-
sary to reduce the voltage in order to maintain a sufficient difference with respect to the gassing volt-
age of 2.4 V/cell. If the temperature falls below 20 °C, it is necessary to increase the charging voltage
in order to ensure optimum charging. The relationship between the temperature and the charging
voltage is shown in the table below. It is valid for the types of battery proposed or provided by Thales.
Please consult the manufacturer if using other types.
BATTERY TEMPERATURE IN °C TRICKLE CHARGE VOLTAGE IN V
10 55.08
15 54.54
20 54.0
25 53.46
30 52.92
The internal temperature in the battery compartment is subject to fluctuations dependent on the time
of day and time of year. The considerable mass of the batteries and the associated high thermal inertia
mean that temperature fluctuations dependent on the time of day are insignificant and can be ignored.
It is necessary on the other hand to determine the average temperature in the battery compartment
during the hot and cold seasons or to estimate it on the basis of experience. The optimum charging
voltage can be read off from the table when the average temperature has been calculated.
It is not necessary in moderate climatic zones to take seasonal fluctuations into account. If the batter-
ies are accommodated inside a shelter or a building, the fluctuations between summer and winter are
not very great, and the mean temperature will not deviate substantially from 20 °C.
In such cases it is not necessary to optimize the trickle charge voltage as described here. This only
becomes necessary if the batteries are installed outside the shelter or in hot or cold zones without
an air−conditioned battery compartment. If the mean annual temperature is known during the instal-
lation phase, adjustments can be carried out by the Thales installation team. Otherwise they should
be carried out by the customer’s own maintenance personnel as follows.
6.3.3.2 Matching the Voltage
NOTE: This procedure is performed once during installation or if other battery types are used.
The battery must be connected. Switch off the transmitters. Using the switches on the front panel
switch off the ACC units except the outer left one, which has to be adjusted first. Beginning with left
ACC unit adjust the ACC units as follows:
− Connect a digital voltmeter to the test jacks on the front panel of the switched on ACC unit.