Why can't the current or voltage be adjusted when using DC power supply?
Phenomenon 1: Output voltage without current, or current without voltage
In either case, the power supply is working normally. The operator should check whether the load is in good contact, whether the load is short-circuited or open-circuited, whether the load meets the specifications and so on. In extreme cases, if the power supply has a voltage output (constant voltage state) and the load line is cut off, the natural output current is equal to zero. Similarly, if the power supply has a current output (constant current state) and the load is short-circuited, the natural output voltage is equal to zero.
Phenomenon 2: When adjusting the voltage, it is found that the no-load voltage can not be adjusted (potentiometer regulation mode).
Some operators prefer to turn the "current-regulated" potentiometer left to the end so that the no-load voltage of the power supply can not be adjusted. This shows that he lacks a substantial understanding of current regulation. Because even if the power supply is idle, it will consume a little current, and you turn the "current regulation" to zero, even a little small current will not be released, of course, no-load voltage can not rise. So the "current regulation" should not be set to zero (it will not happen if you turn right to about a quarter of a circle).
General operation method: When output voltage, the current regulating knob should be rotated clockwise to the end and maintained. The adjusting voltage adjusting knob controls the DC voltage value of the output. When output current, the voltage regulating knob should be rotated clockwise to the end and maintained. The adjusting current adjusting knob controls the output DC current value.
Phenomenon 3: The power supply has both voltage output and current output, but if the voltage is adjusted again, the voltage will not be adjusted. Or the power supply has both voltage output and current output. If you want to increase the current, the current will not be adjusted.
This is because the operator is not clear about the concept of "constant pressure" and "constant current". If the "constant voltage" lamp is on, it shows that the power supply is working in the constant voltage state (voltage can be considered to be the active position). At this time, the output current is determined by the load, not by the operator (current can be said to be the passive position). If the current is de-regulated, the current will not increase. But when the voltage is removed, the output voltage will rise and the output current will rise. Voltage is the main and current is from.
Similarly, if the "constant current" lamp is on, it means that the power supply is working in a constant current state, and the output voltage is not "adjusted", but determined by the load. Only by adjusting the current, the output current will change and the output voltage will also change. (Here the current is the main and the voltage is from)
In a word, we should clarify the relationship between the principal and the subordinate. When the power supply is in the "constant current" state, it can change the voltage and current on the load by adjusting the current and the voltage when it is in the "constant voltage" state.
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