Lab.gruppen PLM Series - Advanced Protection Features; Breaker Emulation Limiter (BEL); Under Voltage Limiter (UVL); Current Average Limiter (CAL)

Operation and Performance
21
PLM Series Operation Manual rev 1.1.9
5.3.4 Breaker Emulation Limiter (BEL
™
)
The Breaker Emulation Limiter is present in the PLM 20000Q. The PLM 20000Q is a powerful amplier that
can draw a considerable current from the mains supply. The BEL models the temperature in the external
breaker and limits the mains current to prevent it from tripping. The BEL can be congured with both a
breaker prole and a current value. The current value can be set from 5 to 32 Ampere RMS.
There are three different proles available for selection:
▸ Conservative - The conservative prole allows no momentary current above the congured threshold.
▸ Fast - The fast prole models the time constant of the tripp-curve corresponding to a fast breaker. It
momentarily allows current above the threshold to pass for a short time, leading to an increased mod-
eled temperature. For the limiter to disengage, the current must reduce below the threshold to enable
the breaker to cool down.
▸ Slow - The slow prole models the time constant of the tripp-curve corresponding to a slow breaker.
It momentarily allows current above the threshold for a longer time, leading to an increased modeled
temperature. For the limiter to disengage the current has to reduce below the congured current for the
breaker to cool down.
The BEL can be congured via the PLM front panel and via the Lake Controller.
5.3.5 Under Voltage Limiter (UVL
™
)
The PLM 20000Q is 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 PLM 20000Q’s 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 sufcient 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 opera-
tion 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 clip-
ping on the subsequent peaks. Limiting is performed by the ISVPL limiter in conjunction with the selected
ISVPL prole. Indication of this condition is shown on the output LEDs.