B&K 1651A, 1652 Constant voltage/constant current characteristic, Series Tracking Operation

OPERATING INSTRUCTIONS___________________________________________________________________________

Constant Voltage/Constant Current Characteristic The working characteristic of this power supply is called

a constant voltage/constant current automatic crossover type. This permits continuous transition from constant current to constant voltage modes in response to the load change. The intersection of constant voltage and constant current modes is called the crossover point. Fig. 7 shows the relationship between this crossover point and the load.

For example, if the load is such that the power supply is operating in the constant voltage mode, a regulated output voltage is provided. The output voltage remains constant as the load 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. The crossover point is indicated by the front panel LED indicators. The crossover point is reached when the CONSTANT CURRENT indicator comes on.

Similarly, crossover from the constant current to the constant voltage mode automatically occurs from a decrease in load. 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 heavy load on the supply and it will operate in the constant current mode, which may be adjusted for a 0.5 amp charging rate. As the battery becomes charged, and its voltage approaches 13.8 volts, its load decreases to the point where it no longer demands the full 0.5 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.

SERIES TRACKING OPERATION

When the series tracking mode of operation is selected, the positive (red) terminal of the “B” supply output is internally connected to the negative (black) terminal of the “A” supply. This allows the power supply to be used as a single 0-to-48 volt power supply simply by using the negative (black) terminal of the “B” supply and the positive (red) terminal of the “A” supply.

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