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| R&S NGE100 voltage jumping around |
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| kladit:
The NGE100x has a adjustable limit for current and a feature called fuse, which also allows to set a current limit. The difference between these two features is that when a current greater than then the adjusted limit is flowing the current limit feature reduces the voltage to a level that allows a contionous flow of maximal the before adjustet current limit, the fuse feature instead switches off the voltage, so no further current can flow. This fuse feature is not well thought to an end. Most circuitry include one or more electrolytic capactior(s) which to get loaded will cause a higher current flow, the so called switch on current, To this or a little greater current the current limit of the power supply has to be adjusted to allow for normal switch on behaviour of the device under test. But there is no way in the NGE100x to adjust the fuse current afterwards, when the normal steady current of the device under test flows. I want the fuse to protect the circuit most and therefore it is needed to set the fuse current later on to a current value less than the switch on current. That is not possible with the NGE100x! There are two solutions to solve this. A) The initial value of the fuse is set to the same as the current limit and is allowed to be change later on to another (mostly lesser) value. B) The different (current limit and fuse) current values for are allowed to set first together with a delay time (to allow the switch on current to happen) for the fuse to get active. R&S guys, you know the problem now, I am awaiting for a new firmware. Regards Klaus |
| RBBVNL9:
@ kladit, A few thoughts: 1. The NGE series has a 'fuse delay' setting. In the manual, this is described as "The fuse delay function is intended to ignore the current peaks set above the current limit that occur during the time set in the fuse delay. This prevents the fuse to be triggered in case of a capacitive load." Seems like what you are looking for! 2. Alternatively, for the situation you described, you might want to use multiple channels in the NGE (there are three identical channels, after all!). You would set a first channel for the longer time protection (current) values you wish, and a second channel - in parallel - that is capable of suppling the higher current during start-up. 3. Moreover, the EasyArb function allows to set different time periods with different current settings. GL! |
| kladit:
@RBBVNL9 The fuse delay is not relative to current limit. It just makes the electronic fuse behave like a slow wire fuse. This is not what I meant. The electronic fuse should switch off the voltage as fast as possible and even for a short increase of current above the set limit in oder to protect the DUT. Therefore its current limit should be adjustable after the switch on current has happend. I don't think this is too difficult to implement for R&S and would make the NGE a more valuable power supply. |
| RBBVNL9:
--- Quote ---But there is no way in the NGE100x to adjust the fuse current afterwards --- End quote --- Are you sure? I just tried this on my NGE, and while the output is on, I can just change the current at which the fuse trips at any moment to the desired value (note that when the Fuse function is activated, the current values you can set (and which are shown in white font on the display) relate to the fuse tripping value, and not any more to the current limiter value). I checked this with an electronic load, and the fuse behaves exactly like you would expect it to. You can also automate the process with EasyArb. Just tested this as follows: - Activated the Fuse function - Set EasyArb step 1 at 5V, 2A, 5 seconds - Set EasyArb step 2 at 5V, 1A, 100 seconds - Connected an electronic load set at 1.5A - Started the PSU and started EasyArb And, indeed, after 5 exactly second, the fuse tripped. |
| kladit:
@RBBVNL9 Question: How can one switch off the fuse function and change the behavoir to current limit only? That means the current stays and the voltage goes down to keep the current the same with a sinking value of the load resistor. |
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