Ac Power Draw And Thermal Dissipation - Crown Com-Tech CT-1610 Service Manual

Rev. 0
3 AC Power Draw and
Thermal Dissipation
"Soft-Start" t" t" t" t" inrush current limiting protects the house "Soft-Star "Soft-Star
"Soft-Star "Soft-Star
circuit breaker when several amps are turned on simul-
taneously.
This section provides detailed information about the
amount of power and current drawn from the AC mains
by the Com-Tech amplifiers and the amount of heat pro-
duced under various conditions. The calculations pre-
sented here are intended to provide a realistic and
reliable depiction of the amplifier. The following assump-
tions or approximations were made:
• The amplifier's available channels are loaded, and full
power is being delivered.
• Amplifier efficiency at standard 1 kHz power is estimated
to be 65%.
• In 8/4 ohm mode, typical quiescent power draw is 55
watts for the Com-Tech 810 and 70 watts for the Com-
Tech 1610 .
• In 70 volt mode, typical quiescent power draw is
90 watts for the Com-Tech 810 and 1610 .
• When running at full speed, typical power draw for the
internal fan is 11 watts for the Com-Tech 810 and 17
watts for the Com-Tech 1610 .
• Quiescent thermal dissipation is related .
• The estimated duty cycles take into account the typical
crest factor for each type of source material.
• Duty cycle of pink noise is 50%.
• Duty cycle of highly compressed rock 'n' roll midrange
is 40%.
• Duty cycle of rock 'n' roll is 30%.
8 Ohm Dual / 16 Ohm Bridge-Mono / 4 Ohm Parallel-Mono
AC Mains
Current Draw (Amps)
Power
Duty
Draw
Cycle
100-120 V 220-240 V
(Watts)
50% 535 6.4
40% 440 5.3
30% 350 4.2
20% 255 3.0
10% 160 1.9
Figure 3.1 Com-Tech 810 Power Draw, Current Draw and Thermal Dissipation at Various Duty Cycles
8 Ohm Dual / 16 Ohm Bridge-Mono / 4 Ohm Parallel-Mono
AC Mains
Current Draw (Amps)
Power
Duty
Draw
Cycle
100-120 V 220-240 V
(Watts)
50% 920 11.1
40% 755 9.1
30% 590 7.1
20% 425 5.1
10% 260 3.1
Figure 3.2 Com-Tech 1610 Power Draw, Current Draw and Thermal Dissipation at Various Duty Cycles
Com-Tech 810 and 1610 Amplifier Service Manual
Com-Tech 810
4 Ohm Dual / 8 Ohm Bridge-Mono / 2 Ohm Parallel-Mono
AC Mains
Thermal Dissipation Current Draw (Amps)
Power
Draw
btu/hr kcal/hr 100-120 V 220-240 V
(Watts)
2.9 785 200 820 9.9
2.4 670 170 670 8.0
1.9 560 140 520 6.2
1.4 450 115 370 4.4
0.9 335 85 220 2.6
Com-Tech 1610
4 Ohm Dual / 8 Ohm Bridge-Mono / 2 Ohm Parallel-Mono
AC Mains
Thermal Dissipation Current Draw (Amps)
Power
Draw
btu/hr kcal/hr 100-120 V 220-240 V
(Watts)
5.0 1300 330 1435 17.3
4.1 1100 280 1165 14.0
3.2 905 230 895 10.8
2.3 705 180 630 7.6
1.4 510 130 360 4.3
• Duty cycle of background music is 20%.
• Duty cycle of continuous speech is 10%.
• Duty cycle of infrequent paging is 1%.
Here are the equations used to calculate the data pre-
sented in Figures 3.1 and 3.2:
Total output power with all
channels driven (watts)
AC Mains Power
=
Draw (watts)
The value used for quiescent power draw includes both
the amplifier's quiescent power draw for the selected
output mode and the power drawn by the fan if one is
installed (these values are listed in the previous column).
The following equation converts power draw in watts to
current draw in amperes:
Current Draw
(amperes)
The power factor of 0.83 is needed to compensate for
the difference in phase between the AC mains voltage
and current. The following equation is used to calculate
thermal dissipation:
(
Total output power with all
Thermal
channels driven (watts)
Dissipation =
(btu/hr)
Amplifier Efficiency (.65)
The constant 0.35 is inefficiency (1.00–0.65) and the fac-
tor 3.415 converts watts to btu/hr. Thermal dissipation in
btu is divided by the constant 3.968 to get kcal. If you
plan to measure output power under real-world condi-
tions, the following equation may also be helpful:
(
Total measured output power
Thermal
from all channels (watts)
Dissipation =
(btu/hr)
Amplifier Efficiency (.65)
L O A D
AC Mains
Thermal Dissipation Current Draw (Amps)
Power
Draw
btu/hr kcal/hr 100-120 V 220-240 V
(Watts)
4.5 1125 285 810 9.7
3.7 945 240 670 8.0
2.8 765 195 525 6.3
2.0 585 150 385 4.6
1.2 405 100 245 2.9
L O A D
AC Mains
Thermal Dissipation Current Draw (Amps)
Power
Draw
btu/hr kcal/hr 100-120 V 220-240 V
(Watts)
7.8 1915 485 1590 19.1
6.4 1590 400 1295 15.6
4.9 1270 320 1000 12.0
3.4 950 240 700 8.4
2.0 630 160 405 4.9
]
x Duty
Cycle
+ Quiescent Power
Draw (watts)
Amplifier Efficiency (.65)
AC Mains Power
Draw (watts)
=
AC Mains Power
x
Voltage Factor (.83)
Duty
x x .35
Quiescent Power
Cycle
+
Draw (watts)
x .35
Quiescent Power
+
Draw (watts)
70 V
Thermal Dissipation
btu/hr kcal/hr
4.4 1190 300
3.6 1020 260
2.9 850 215
2.1 680 170
1.3 510 130
70 V
Thermal Dissipation
btu/hr kcal/hr
8.7 2140 540
7.1 1790 450
5.5 1435 365
3.8 1085 275
2.2 730 185
)
x 3.415
)
x 3.415
3-1 3-1