B&K Precision 1747 - Manual - Manual (Page 16)

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constant as the load current increases, up until the point where the preset current
limit is reached. At that point, the output current becomes constant and the output
voltage drops in proportion to further increases in load current. The crossover point
is indicated by the front panel LED indicators. The crossover point is reached when
the CV indicator goes off and the CC indicator comes on.
Similarly, crossover from the constant current to the constant voltage mode
automatically occurs from a decrease in load current. A good example of this would
be seen when charging a 12-volt battery. Initially, the open circuit voltage of the
power supply may be preset for 13.8 volts. A low battery will place a high load
current on the supply and it will operate in the constant current mode, which may be
adjusted for a 1 amp charging rate. As the battery becomes charged, and its voltage
approaches 13.8 volts, its load current decreases to the point where it no longer
demands the full 1 amp charging rate. This is the crossover point where the power
supply goes into the constant voltage mode.
Figure 7 - Constant Voltage/Constant Current Characteristic
4.6 Saving the Power Supply’s Current State
The current state of the power supply is saved after 2 seconds from the last
adjustment or after the “SAVE” command is received through the RS232 interface.