Temperature Protection - Lab.gruppen PLM series Operation Manual

Operation and Performance
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 measure-
ments in the power supply and DSP areas. If temperature in any area reaches a critical level then a warning
is displayed. 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.
5.3.8.2 Power Output Channels
A power output channel temperature warning or fault is indicated in one of the front panels LEDs (in the
right-hand soft function buttons).
▸ A warning is indicated by a static yellow LED and adjacent warning message: TEMP WARN:CH
▸ A fault is indicated with a static red LED and adjacent warning message: TEMP FLT:CH
In either case, a report is also sent via the control network to the Lake Controller software. If a temperature
fault condition arises on a power channel, the output of that channel will be muted.
5.3.8.3 Power Supply / DSP
If the power supply or DSP area overheats, the fault is indicated by a static red LED in the top left function
button; the adjacent on-screen text displays the fault message TEMP FLT:PSU or TEMP FLT:DSP respec-
tively. In either case, a report is sent to the Lake Controller software. If a temperature fault condition arises
on the power supply or the DSP area, the output of all channel will be muted.
5.3.8.4 PLM 20000Q
For the PLM 20000Q a temperature dependant limiting feature is also present. At temperatures above the
critical warning level and below the dangerous fault level, the ISVPL threshold is slowly reduced to decrease
the output power and cool down the device. This enables the device to continue to pass audio, although
with a reduced amplitude, in extreme conditions. If reducing the ISVPL threshold does not cool down the
device a temp fault will still be issued when the dangerous temperature level is reached.
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PLM Series Operation Manual rev 1.1.9