Argantix KDC 100-100, User Manual

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User Manual
KDC Series II DC Power Supplies 55
4.6.1 Constant Power mode operation profile
The constant power mode attempts to maintain constant power into the load. This concept is
bound by the voltage and current mode limitations however. Thus, it may not be possible to
maintain constant power mode under all load conditions. For example, if the required voltage to
maintain constant power exceeds the programmed (set) voltage, the power supply will revert to
CV mode once the maximum voltage is reached and the output power will be less than set in the
POWER field of the CP mode screen. The same is true if the required load current exceeds the
current limit set point.
The constant power mode operating profile is shown below. The Vset and Iset bounds are the set
values for voltage and current limit.
Vset
Iset
CP mode
CV mode
CC mode
User sets Vset, Iset and CP mode = nnn Watt
If Iout < Iset and Vout < Vset, KDC is in CP mode, varies voltages
as needed to maintain P.
If Iout > Iset, KDC switches to CC mode. Current stays at Iset,
voltage can vary as needed. P is not CP setting.
If Vout > Vset, KDC switches to CV mode. Current may vary and P
is less than CP setting.
Figure 4-7: Constant Power Mode Profile.
The Constant Power mode requires power measurements to operate. Obtaining these
measurements takes time as several readings are averaged to avoid instability. As such, changes
in setting will typically occur at a slower rate than the CV or CC modes. Also, the voltage is
dominant parameter used in the CP mode.
This means that when the CP mode is first selected and the output is turned ON, the voltage will
be set to the programmed value until the CP mode determines that the voltage needs to be
reduced as a function of the load detected. To avoid damage to the EUT, do not set the voltage
past the maximum level the EUT can sustain.
Once engaged, the output can be turned off. When turned back on, the voltage will resume at the
last value in effect in the CP mode. If the load has been changed, it will take some time to react
again.
Note: KDC units with firmware revisions below 1.11 do not have the CP mode enabled.