Lab.gruppen PLM 20K44 Operation Manual page 21

5.3.6. Current Average Limiter (CAL™)
The Current Average Limiter (CAL) monitors the RMS current drawn from each power output channel to ensure
that the power output stages are not overloaded. When activated, it regulates the current to a safe level to
protect the channel. The CAL should not be activated in normal usage. CAL activity is shown by red indication on the
affected Power channel and a corresponding text description on the front panel, in Lake Controller and CAFÉ software
programs. Refer to section 9.1 for more information on warnings and faults.
5.3.6.1. PLM5K44
For the PLM5K44, the CAL threshold is calculated per Power channel based on the actual ISVPL setting. A high
ISVPL setting results in a lower average current, whereas a lower ISVPL setting allows for a higher average
current.
NOTE: For PLM5K44, to optimize the CAL's behavior when playing into a low impedance
load - manually set the desired ISVPL to reflect the real peak Voltage output to allow
for a higher average current.
5.3.7. Voltage Clip Limiter (VCL)
If current draw from the unit's power supply is too high, the PSU's regulation capability may be exceeded and
the internal voltage rails may drop and cause clipping. If this occurs, the VCL acts rapidly to prevent clipping on
the subsequent peaks. Limiting is performed by the ISVPL limiter in conjuction with the selected ISVPL profile.
Voltage Clip is shown by red indication on the affected Power channel and a corresponding text description on
the front panel, in Lake Controller and CAFÉ software programs. Refer to section 9.1 for more information on
warnings and faults.
5.3.8. Temperature Protection
5.3.8.1. Overview
PLM+ devices are equipped with a sophisticated temperature sensing system that provides protection
from overheating which may occur as a result of inadequate ventilation or excessive power output. Thermal
measurements are made at several points within each power output channel along with measurements in the
continuously, with the highest possible output, and prevent shutting down. If temperature in any area reaches
a critical level, a warning is displayed. The warning is issued at approximately 80% of the maximum allowable
temperature. If the temperature continues to increase, a limiter is engaged that limits signal peaks to reduce further
heat accumulation. Limiting is accomplished by gradual reduction of the ISVPL thresholds. In the extreme case
where the limiter cannot reduce heat accumulation and temperature reaches a dangerous level, a fault is displayed
and audio is muted.
Each power output channel, the power supply, and DSP area have separate indications. For all temperature faults,
temperature monitoring will continue at 0.5 second intervals, with the output remaining muted. When the area has
cooled below the dangerous threshold, the fault condition is cleared and audio is restored.
5.3.8.2. Power Output Channels
A Power output channel temperature warning or fault is shown by yellow or red indication on the affected
Power channel and a corresponding text description on the front panel, in Lake Controller and CAFÉ software
programs. Refer to section 9.1 for more information on warnings and faults.
5. Operation and performance
PLM+ SERIES Operation Manual rev 3.0.1
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