Fault protections are systems designed to protect
people from severe or fatal electric shocks and avoid severe
damages on the amplifier or the loudspeakers in case of
electrical parameters out of scaling or critical changes in
environmental conditions.
The architecture of Powersoft’s amplifiers includes
several protection mechanisms triggered by harmful
signal and temperature. Protection systems and triggers
are independently implemented in the power supply
section (power supply protection) and the amplifier section
(amplifier protections) in order to minimize system damages
and maximize efficiency.
In case any limiter requires >17dB of gain reduction,
each channel’s relative PROTECT pin (PL1000 - #10=ch1
#25=ch2, PL3000 - #10=ch3 #25=ch4) will become active.
If any limiter requires a >20 dB reduction, the module
will shut off.
12 : 1.Fan Control
Fan starts to run as soon as the amp module measures
a temperature greater than 60°, the fan control keeps fan
at maximum speed for the first 2s, then its speed will be
controlled according to operating temperature. When the
amp module reaches 75°, the fan starts to run at maximum
speed.
The fan is not included in the package, Powersoft rec-
ommends the following (or equivalent):
f
40x40= SUNON series MB60151Vx, or series MF60151Vx
f
80x80= SUNON, series ME80151Vx
TABLE 1: TempMon
12 : 2.Power supply protections
Power supply protections aim to avoid damages due to
stress of the Power supply or to isolate a faulty section in the
electrical power system from the rest of the device in order
to prevent the propagation of the fault and limit damages.
12
Protections
12 : 2.1. Primary AC mains overcurrent protection
A 15A time-delay fuse (Littelfuse series 326) prevents
against dengerous mains overcurrents in case of a internal
failure. The fuse holder is placed on the L wire on the
mains cable assembly provided as optional cable kit. In
case Powersoft cable would not be used, a similar cable is
mandatory, please follow assembly instructions described
in Cable Kit paragraph.
12 : 2.2. Primary AC mains overvoltage protection
AC mains overvoltage threshold is set to 280 V
RMS
. If
the AC mains voltage exceeds 280 V
RMS
the primary power
supply stops working, but the auxiliary remain active.
The power supply turns on again when the AC mains
voltage drops under 275 V
RMS
.
12 : 2.3. Primary thermal protection
The temperature is detected at the power supply’s
MOSFETs located on the Main Board’s bottom side and
inside the power transformer.
The limiting factor is set as follows: 0dB @ 105°C, and
-20dB @ 125°C. When the temperature exceeds the safety
threshold of 125°C, the system switches off.
T (°C)
TempMon
25
2.59
30
2.53
35
2.45
40
2.31
45
2.16
50
2.00
55
1.83
60*
1.64
65
1.43
70
1.22
75**
0.98
80
0.74
85
0.45
90
0.11
*
fan
activation
threshold
**
max
speed
Another sensor is located on the heatsink, when the
temperature exceed the safety threshold (0 dB @70 ºC, -20
dB @85º C), the system switch off.
Protections | 12
0
-10
-20
80
95
125
-30
o
C
dB
-∞
Gain Reduction
Safety
Shutdown
Transformer
temperature limiter
105
0
-10
-20
0
65
70
85
-30
o
C
dB
-∞
Gain Reduction
Safety
Shutdown
Heat-Sink
temperature limiter
