Amplified Controller Protection Systems; Thermal Protection; Dc Protection; Mains Supply Under & Over-Voltage Detection - L-Acoustics LA8 Manuel Utilisateur

LA8
AMPLIFIED CONTROLLER
User Manual
VERSION 1.2
7.6

Amplified controller protection systems

Most of the protection systems that insure the integrity of the unit's electronic vital parts are managed by the Operating
System (OS). This allows real-time monitoring and optimal performance with a high level of safety even under extreme
conditions.
7.6.1

Thermal Protection

The fans associated to the heat sinks operate permanently, but as long as the temperature remains below 40 °C they
run at their slowest speed and can hardly be heard. The highest detected temperature controls the speed of the fans.
Above 40 °C the speed is increased until it reaches its maximum value.
If the OS detects a temperature of more than 85 °C at the heat sinks the input signals delivered at all amplifier output
channels are attenuated. The input signal is muted if the temperature exceeds 96 °C.
7.6.2

DC Protection

Each of the four amplifier channel outputs is monitored at all time for sustained presence of DC voltage above the 3 V
threshold. If such threshold is exceeded at any of the outputs the main SMPS or the concerned output channel will be
automatically switched off.
7.6.3 Mains supply Under & Over-voltage Detection
The LA8 amplified controller uses an auto-sensing SMPS for mains input voltages 120/230 V, 50-60 Hz (100 V version
exists for Japan). The mains supply voltage is monitored at all times for under & over-voltage: if voltages outside a plus
or minus 10 % range are detected the auto-sensing SMPS will switch off.
When the mains supply voltage returns to an acceptable value a soft start sequence will be automatically engaged.
7.6.4

Mains supply Failure Detection

The mains supply is monitored at all times for mains cycles discontinuity. If the mains supply skips about 2 cycles the
auto-sensing SMPS will switch off.
A soft start sequence will be automatically engaged when the mains supply returns to nominal state.
7.6.5

Peak Over-Current Protection

The amplified controller main SMPS current is continuously monitored. If an over-current is detected the main SMPS is
immediately switched off. Should there be an internal failure this feature prevents other parts from being damaged.
The output stages also are continuously monitored for possible current surges. There are two limiting levels of over-
current depending on output voltage (limitation will be set automatically). This approach improves reliability without
degrading sound quality.
7.6.6

Mean Over-Current Protection - Fuse Protection

The average mains current can peak temporarily depending on load impedance and type of signal, at values several
times higher than the nominal value supported by the fuse protection. In order to avoid shut-down of the power supply
(due to the over-current protection of the SMPS controller) the amplitude of the input signals will be limited.
LA8_UM_EN_1.2
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