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PLM Series Operation Manual rev 1.1.3
7. Operation and Performance
Table 7.2.2a: Asymmetrical load power ratings
for PLM 10000Q
Load
Impedance
(ohms)
2.0
2.7
4
8
16
Max.
Output
power
(Watts)
2350
2900
2400
1200
660
Table 7.2.2b: Asymmetrical load power ratings
for PLM 14000
Load
Impedance
(ohms)
2.0
2.7
4
8
16
Max.
Output
power
(Watts)
7500
6300
4400
2300
1150
7.2.3 Power over time
Power ratings given above are applicable for PLMs running at these levels for a period of 60 minutes. Due
to thermal considerations in the power supply and elsewhere, it is possible to draw higher power levels for
a shorter period of time. The graph below illustrates, for the example PLM 10000Q, how the rated power
figures are derived and the higher short-term capability.
Peak output voltage at “max power burst”
Figure 7.2.3: Power rating levels over time
Power ratings are based on a “real-life” duty cycle of 25 ms full power every 400 ms. Between bursts, a
lower signal level applies, such that the continuous average power is 1/8th of the rated power.
In reality, when some channels are delivering less than maximum rated power, energy reserves in the PSU
are available to permit other channels to deliver more power. The graph shows the peak output voltage over
time for a continuous sine wave is applied.
If all four channels are driven with the same signal into the same impedance (solid red line), then the rail
voltage (dotted red line) will drop faster than when two channels are delivering “max power” (solid blue line)
and two channels are delivering “half power” (solid orange line). This is termed asymmetric loading. The rail
voltage for this is the dotted blue line.
It can be seen that higher power output is available for 25 ms bursts with asymmetric loading.
