Lab.gruppen PLM 20K44 Operation Manual page 21

5. Operation and performance
5.3.5. Under Voltage Limiter (UVL™)
PLM+ devices are equipped with an under voltage limiter. With mulitple powerful devices on a mains distribution
line, heavy current loads risk the reduction of voltage below that required for devices to function. The UVL
reduces the mains current draw when voltage drop below 80 V. The amount of reduction applied increases as
mains voltage drops towards 65 V, then at 65 V the power supply is shut down. The mains supply is continually
monitored and when sufficient voltage returns the power supply automatically restarts.
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, but if it is, its operation is indicated by an active
LED and the message CAL ACTIVE. Further indication is given within the Lake Controller software.
5.3.7. Voltage Clip Limiter (VCL)
If current draw from the PLM+'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 conjunction with the selected ISVPL profile.
Indication of this condition is shown on the output LEDs.
5.3.8. Temperature Protection
5.3.8.1. Overview
PLM+ Series 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 power supply and DSP areas. If temperature in any area reaches a critical level then a warning is displayed
and gain reduction is applied. If the temperature continues to increase and reaches a dangerous level then 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.
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PLM+ SERIES Operation Manual rev 1.0.0