User manual

CD5.121
CD–Series
DC/DC Converter; 12V, 8A
Jan. 08 / Rev. 1.1 DS-CD5.121-EN / All parameters are specified at 12V, 8A and 24Vdc input at 25°C ambient unless otherwise noted.
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19/21
25.8. PARALLEL USE FOR 1+1 REDUNDANCY
DC/DC converters can be paralleled for 1+1 redundancy to gain a higher system availability. Redundant systems
require a certain amount of extra power to support the load in case one DC/DC converter unit fails. The simplest way
is to put two DC/DC converters in parallel. In case one converter fails, the other one is automatically able to support
the load current without any interruption.
Furthermore, redundant systems can be built by using a DC/DC converter powered from a battery and a power supply
with AC input.
Recommendations for building redundant power systems:
a) Use the decoupling module YR2.DIODE in combination with two CD5.121.
b) Use separate input fuses for each DC/DC converter.
c) When possible, connect each DC/DC converter to different power sources.
25.9. CHARGING OF BATTERIES
The power supply can be used for float-charging of lead-acid or maintenance free 12V VRLA batteries.
Instructions for charging batteries:
a) Ensure that the ambient temperature of the power supply does not exceed 50°C.
b) Set the output voltage on a disconnected load, very precisely to the end-of-charge voltage according to the
expected battery temperature.
End-of-charge voltage 13.9V 13.75V 13.6V 13.4V
Battery temperature 10°C 20°C 30°C 40°C
c) Use a 10A circuit breaker (or blocking diode ) between the power supply and the battery.
d) Ensure that the output current of the power supply is below the allowed charging current of the battery.
e) The return current to the power supply is typ. 15mA at 12.5Vdc when the power supply is switched off (except in
case a blocking diode is utilized).