Questions on power supply

[mngeow]

I've recently begun my lab sessions and begun using the DC power supply. There are a few things that I'm curious about.

Firstly , what is the maximum output current and voltage achievable by the DC power supply? I'm afraid to just crank up the voltage and current knob all the way , don't want to blow the fuse.

Secondly , I've noticed this C.C / C.V light that turns red and green depending on my current and voltage setting. I've read online that it stands for Constant Current and Current Voltage. What do they mean and how do I enter either states?

Thanks!

 

[Dan Mills]

A typical bench supply had operates in constant voltage mode up until you draw more current then the maximum set on the current control knob whereupon it reduces the voltage to maintain the current at the level selected (Constant current mode).

They all have a maximum current limit set internally such that even if the valtage and current knos were all the way to the right, a short circuit will not blow anything.

Try the following:
With nothing connected to the supply, turn the volathe all the way up (Usually 30V or so), note that no current flows.

Now Turn the current knob up to say 500mA and with the voltage set at 30V, short circuit the supply, note that the voltage drops to nearly zero, the current rises to a limited value and the supply switches into constant current mode.

Replace the short circuit with a 1 ohm, 2W resistor, note that the supply is now outputting half a volt and 500mA, turn the current limit up and down (maximum 2A) and note theat the supply adjusts voltage to maintain the current at the specified level.

Bench supplies are hard to kill, sometimes this is not true of the things you connect to them....

Regards, Dan.

 

[D.A.(Tony)Stewart]

A good lab supply can often deliver more A and V than VA product,and so may be specified as such.

Read the specs as all V,A,W limits should be specified for certain load types.

THe best will be designed for abrupt short circuit or large inductive kickback, (e.g. motor ) if specified.

But for most loads, no worries. CC and CV adjustments let you protect your device being tested.

 

[Eshal]

Try this with your power supply. BUT DON'T TOUCH ITS PINS AND DON'T CONNECT ANYTHING OR ANY CIRCUITRY TO IT DURING THIS EXPERIMENT.

1) Switch on the power supply.
2) Set the the both knobs at zero.
3) Increase the current knob just little but above zero.
4) Now increase voltage and keep increasing until you see a red light.
5) As you see red light then stop increasing voltage knob and again increase the current knob further but little as red light turns off.
6) Again start increasing voltage knob and after certain turning again red light will glow.

This is that you have need to maintain the current level.