System and signal protections
16
Fault protections are systems designed to protect peo-
ple from severe or fatal electric shocks and avoid severe
damages on the amplier or the loudspeakers in case of
electrical parameters out of scaling or critical changes in
environmental conditions.
The architecture of Powersoft’s ampliers encompass
several protection mechanisms triggered by harmful sig-
nal and temperature. Protection systems and triggers are
independently implemented in the power supply section
(power supply protection) and the amplier section (ampli-
er protections) in order to minimize system damages and
maximize efciency.
16 : 1.Power supply protections
Power supply protections aim to isolate a faulty section
in electrical power system from the rest of the device in
order to prevent the propagation of the fault and limit device
damages.
16 : 1.1. Primary AC mains overcurrent protection
AC main overcurrent are ltered by time-lag fuses (also
known as time-delay or slow blow-fuse): 20 A time-lag fuses
and 16 A time-lag fuses are used on X8 and X4 respectivelly.
The purpose of the time lag fuse is to allow the supply in
electricity for a short time before the fuse actually blows. If
the time-lag fuse blows out the amplier switch off: replace
the fuse with a proper time-lag fuse in order to restore the
full functionality of the amplier.
16 : 1.2. Primary AC mains overvoltage protection
AC mains overvoltage threshold is set to 510 V
rms
. If the
AC mains voltage exceeds 510 V
rms
the power supply stop
working; the device does not turn completely off but falls in
a “sleeping” mode: the power supply turns on again when
the AC mains voltage drops down.
AC mains overvoltage are well tolerated by the power
supply: no damages can be caused to the system even in
case of severe overvoltage up to 510 V
rms
.
16 : 1.3. Primary thermal protection
The working temperature of the power supply controls
the fans speed and the rails voltage. In very harsh condi-
tions, if the fans are unable to maintain the overall tempera-
ture into the operating range and components tolerances,
the primary hardware thermal protection starts lowering the
rails voltage in order to lower the system heat.
The process is auto-adaptive and aims to maintain
the system up even in heavy thermal condition. If the rails
voltage drops down to ±33 V the system shut down the
amplier section, the power supply still running. This may
happen rarely, even in harsh conditions: the amplier does
not switch off but neither signal processing nor fan cooling
are active. In these conditions, while the temperature slowly
decreases, the rails voltage rises: when the rails voltage
reaches ±33V, the ampliers section switch on again. If
cooling is not effective, the system may start oscillate.
16 : 2.Amplifier protections
Amplier protections are triggered by audio signal cur-
rent and voltage – by comparing input and output – and
thermal feedback.
16 : 2.1. Harmful signal protections
Bad signals can cause amplier and loudspeakers
damages. In order to limit damages, harmful signal triggers
specic protections.
16 : 2.2. Output short circuit
If the load impedance is too low or the loudspeaker line
has a short circuit (because of voice coil damages, wires
short circuit, improper wiring, etc), the amplier output cur-
rent rises to harmful values.
When the output current exceeds 130 A, the system shut
down the amplier section, the power supply still working.
After 2 seconds the system tryes to switch on the amplier
section: if the short circuit still persists, the current rises and
the amplier is switched off again. The system toggles the
ampliers on and off every 2 seconds until the short circuit
is removed.
16 : 2.3. High frequency stationary loud signals
High frequency stationary loud signals, like steady sinu-
soid signals – improperly referred as continuous signals – tend
to stress the amplier section as well as the loudspeakers
voice coils.
When a high frequency stationary loud signals is feed
into the amplier the system limits its mean current depend-
ing on its level and frequency. The process is auto adaptive
and frequency driven: at higher frequency the limiter acts
faster.
16 : 2.4. DC fault protection
In order to protect your speakers from mechanical
damage caused by a DC signal coming from the ampli-
er’s output, a DC detection circuit is placed between the
amplier’s output stage and power supply. If a DC signal or
excessive subsonic energy appears at a channel output an
instantaneous protection circuit will mute the compromised
channel pair.
24 | X Series | User guide
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