32 Product description
from power supply.
The condition of current derating is turned off when the power supplied back to the va-
lue set by the user and if the maximum current supplied from power supply is less than
or equal to the maximum allowable value for continuous operation.
Thermal management on power supply (Lifextender) ®
The algorithm of power supply management, function of temperature, is the same as
that in the RF group, and is connected logically “OR” to it.
The first level of Derating (which acts directly on the output power) is activated when
the power supply temperature exceeds 75 ° C, while the second level is activated if,
with the first ineffective, the temperature is not stable below this value. In this second
case the output power is brought below the - 3 dB, with the same procedure already
described in RF section.
Fault management on RF modules (Lifextender) ®
It makes the maximum output power management depending on the number of RF
amplifier modules being properly operated.
If one or more MOSFETs are considered failed (this happens when the current consum-
ption is less than 10% of the average), RF output power is reduced to the expected
value in the presence of failure experienced. The failure case histories and maximum
power achievable are described in a complex table obtained through experimentation,
and are designed to stop MOSFETs failure, that are still operating, by avoiding that are
overly stressed by the mechanism of ALC (which would call these to supply the power
output missing).
To avoid an unnecessarily large number of alert SMS, during this stage are not sent: any
alert SMS, if validated, will be sent only after the output power adaptation procedure,
according to the parameters table, and only if -3dB condition is verified.
Cooling Management on fans group (Lifextender) ®
The fan speed is adjusted, depending on the actual cooling needs, from a minimum of
60% to a maximum of 120% (these values may differ by different models of fan used).
The cooling need is estimated on the basis of accurate temperature measurements
that are made on RF MOSFETs and on power supply. The Cooling Management aims to
extend the lifespan of the fans, to minimize the amount of dust that can be carried by
the airflow, and to guarantee a safe operation of the apparatus, even under extreme
conditions of temperature.
5.6.2 Hardware protections
The hardware protection system includes:
• fast electronic and fuse protection on power supplies;
• fast electronic protection on fans power supply ;
• fast protection against excessive reflected power (ROS/VSWR), caused by a strong
mismatch of the load. This protection occurs when the value of reflected power
exceeds 10% of the direct power.
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