EPS Stromversorgung 06230204, Руководство по эксплуатации, Страница: 40 / 66

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EPS Stromversorgung GmbH
Alter Postweg 101 • 86159 Augsburg
Germany
PS 9000 2U Series
Fon: +49 821 / 570451-0
Fax: +49 821 / 570451-25
www.eps-germany.de
info@eps-germany.de
3.2.3 Power regulation / constant power / power limiting
Power regulation, also known as power limiting or constant power (CP), keeps the
DC output power of a power supply constant if the current flowing to the load in
relation to the output voltage and the resistance of the load reaches the adjusted
power value according to P = U * I resp. P = U² / R. The power limitation then regu-
lates the output current according to I = sqr(P / R), where R is the load’s resistance.
Power limiting operates according to the auto-range principle such that at lower
output voltages higher current flows and vice versa in order to maintain constant
power within the range P
N
(see diagram to the right)
Constant power operation primarily impacts the output current. This means, the
adjusted maximum output current can not be achieved if the maximum power value
limits the output current according to I = P / U. The adjustable set value of current,
as indicated in the display, is always only an upper limit.
While the DC output is switched on and constant power mode is active, then the condition “CP mode active” will
be shown on the display by the abbreviation CP and can also be read as a status message via digital interface.
3.2.3.1 Derating
Due to fusing and cross sections of conductors and the extended input voltage range, power supply models as
from 1500 W have a fixed derating, which becomes active below a certain input voltage level (for value see „1.8.3.
Specific technical data“ ). It then derates the maximum available output power for a 1500 W model down to 1000 W
and for a 3000 W model down to 2500 W. The derating only affects the power stages, so the full range for power
set value adjustment remains, though the device will switch earlier to constant power operation. In this situation,
constant power operation can not be indicated by status “CP”. Active derating can then only be detected by read-
ing the actual values of voltage and current and by calculating the power.
No status “CP” available if the adjusted power set value (Psel) is bigger than the derated actual
output power of the device.