D&b Audiotechnik E-PAC Hardware Manual - page 10
E-PAC, Hardware manual
(1.0E)
Page 10 of 24
The maximum current draw during the power up phase is dependant
on the mains voltage, however nominal values are 2 A (peak) at 230
V and 4 A (peak) at 115 V.
The nominal operating range of the E-PAC is between 85 V and
265 V (100 V –15% /230 V +15 %). Where voltages outside of
this range are present, a self-resetting protective circuit responds
quickly to isolate the internal amplifier power supply leaving only a
supervisory circuit to monitor the mains voltage. The display will
clearly indicate the fault and voltage value, the display illumination
switching off after 10 seconds.
The supervision circuit will operate up to 400 V; this allows the
E-PAC to survive connection across two phases of a three phase
supply.
To prevent the E-PAC from cycling on and off with fluctuating
mains power supply voltages, the switching thresholds are delayed
dependant on the condition breached. These voltage thresholds
and corresponding transition delay times are listed in the table
below.
Main
voltage V
RMS
Condition
from
⇒ to
Delay
276 V
ON
OFF
1 msec.
267 V
OFF
ON
2 sec.
83 V
OFF
ON
2 sec.
77 V
ON
OFF
20 msec.
To ensure a fast response to irregular mains conditions, the mains
voltage is registered in the E-PAC as an instantanous peak value,
the switching thresholds correlated to that peak value. Peak values
are converted to rms values for display purposes. However a
real-world AC mains power supply is not typically represented by a
perfect sinewave, therefore, the peak-to-rms conversion is based on a
typical sinewave with a flat top at 96% of the amplitude of an ideal
sinewave.
As a consequence, the displayed voltage and the actual
switching thresholds will depend on the shape of the mains voltage
or the quality of the mains power supply, respectively.
2.5. Cooling
The aluminium enclosure acts as a heat sink for the E-PAC power
amplifier; it is therefore convection-cooled. To prolong the life of
components inside the E-PAC, a small fan located at the front of
the E-PAC intakes cooling air through an opening in the rear
panel. The quiet running fan is activated at two temperature
thresholds. One at 30 C (86 F) and a second, whereby the fan will
draw air at a faster flow rate, at above 45 C (113 F).
WARNING!
Do not touch the heat sink. During operation the cooling fins of the
heat sink on the enclosure of the E-PAC can reach temperatures of
80 C (176 F). The front and rear panels do not form part of the
heat sink and can be touched at any time.