Lab.gruppen PLM 20000Q - Manual (Page 26)

20
Operation and Performance
PLM Series Operation Manual rev 1.2.3
The ISVPL threshold may be set at any level between 17.8 V and 600 V via the PLM’s menu system. For
further details, please refer to section 7.11.2.5 of this manual, and also to the PLM Series chapter in the
Lake Controller User Manual.
PLM devices that have a smaller peak output voltage can still set the ISVPL threshold up to 600 V. When
a threshold is set above the maximum capability of a power output channel, the maximum ISVPL for that
product will be automatically set. Therefore, the ISVPL threshold can be in at the Module for the speaker’s
maximum capability, and the Module file remains cross-compatible with all PLM Series devices.
5.3.2 Current Peak Limiter (CPL)
The output Current Peak Limiter (CPL) ensures that the power output section will not be damaged by forcing
it to deliver current levels at the outputs that exceed the maximum current ratings of the output transistors.
The CPL keeps the output transistors within their Safe Operating Area (SOA). The CPL is non-adjustable.
CPL activity is indicated on the power output channel LED (embedded in the associated output channel’s
function button to the right of the LCD). Activity on an affected channel results in a flashing red indication
together with a CURRENT CLIP warning message displayed on the screen adjacent to the LED. A warning is
also displayed on the controlling PC via the network.
This condition indicates an attempt to draw excessive current at the output. The output is attenuated until
the output current falls below the maximum current rating. Limiting is performed by the ISVPL limiter in
conjunction with the selected ISVPL profile. Please refer to the Technical Specifications in chapter 11 for
further details regarding ratings.
If excessive current is indicated, check the output cables and examine the
loudspeaker. If impedance appears normal, you may rectify the condition by
altering the ISVPL settings or lowering input levels. CPL indication can be
triggered by excessively low output impedance, possibly the result of too
many loudspeaker cabinets connected in parallel.
5.3.3 Power Average Limiter (PAL)
5.3.3.1 PLM 10000Q and PLM 14000
The Power Average Limiter (PAL) controls the AC current into the power supply. Power consumption is
limited to the rated design parameters of the power supply, ensuring that the PSU will never be overloaded.
Also, high-power products such as those in the PLM Series can potentially draw more current (with output
devices still within safe operating areas) than is allowed by the external mains breaker.
The PAL protection feature can help prevent the supply’s external breaker from tripping within time intervals
of less than three minutes. For longer time intervals, it is the responsibility of the user to ensure that the
average level of the audio is within limits that ensure that the breaker doesn’t trip.