Manual
5. Operation and performance
24
PLM+ SERIES Operation Manual rev 1.0.0
5.3.11. Short Circuit Protection
A low impedance or short circuit at the power output terminals is detected when the output current is high (Current
Peak Limiter is active) and, simultaneously, the peak output voltage is below a predetermined threshold. When
this situation occurs, the output stage is muted to protect it from damage. Operation of the short circuit protection
system is indicated by an output channel LED (in the right-hand soft function buttons) showing steady red. The
adjacent fault message will show SHORT CIRCUIT. It is also reported as a fault via the control network to the Lake
Controller software. The presence of a short circuit (or low impedance) is re-tested every six seconds, and the
output remains muted until the fault clears.
5.4. Power Supply
The R.SMPS (Regulated Switch Mode Power Supply) is designed to keep supply voltage rails at optimum levels
even when the mains voltage drops. Mains voltages can drop as much as 20% below nominal before there is any
effect on rail voltages. Thus the R.SMPS can deliver full rail voltage to the output stage at all times, allowing the
PLM+ to exhibit consistent transient response and a clean LF response. PLM+ features a universal power supply
with power factor correction (PFC). The device can accept any mains voltage, from 65 V to 265 V, allowing it to
function worldwide in many different congurations. The PFC reduces current peaks on the lines and reduces the
requirements placed on the mains distribution system. PLM+ units offer an unparalleled power factor extremely
close to one.
5.4.1. Low Inrush Current
High power ampliers with inadequate inrush current limiting can draw considerable current from the mains at turn-
on, sometimes tripping a fast-acting mains breaker. The PLM+, however, has very low inrush current to prevent
tripping of breakers.
Several PLM+s can, under normal conditions, be powered up simultaneously. If you do experience problems
powering up multiple PLM+s simultaneously, they must either be turned on manually in an ordered manner, or
sequenced remotely using the Lake Controller software’s Global Control feature. Alternatively, the capacity of the
mains supply should be increased.
Note: If insufcient power is available to allow simultaneous power-up, then there is probably insufcient
capacity for full power output during operation. It is recommended that additional capacity is added to
the mains power distribution system.