Timeline for How to track down <100µA earth leakage on DC rails
Current License: CC BY-SA 4.0
8 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| May 29 at 21:13 | comment | added | Sandro | The supply of the robot : theoretically about 50A, in practice limited by the 8 ohms resistance of the cable, and by the 32A circuit breaker. For the lab supplies, the small ones are 60V 3A and 30V 5A. If need be, I can use the big one used for testing motors : I don't have exact ratings in mind, but >400V >20A. NB : when I said "put 50Vdc", I meant between earth and ground. So the current will be in the 2.5µA-500µA range | |
| May 29 at 20:58 | comment | added | Voltage Spike♦ | How much current can the supply source? | |
| May 29 at 20:55 | comment | added | Sandro | So it seems unlikely to be AC. But I will still try next time to put 50Vdc with the lab supply for several minutes and check if the current decreases over time or not | |
| May 29 at 20:53 | comment | added | Voltage Spike♦ | DC can flow forever, AC stops at some point if there is no capacitance, if it takes a few seconds to stop flowing, then that is a lot of capacitance | |
| May 29 at 20:50 | comment | added | Sandro | The voltage between earth and 0Vdc or 320Vdc remains stable (at +50V or -50V) for 2 seconds. So if after 2s there is still current, I would call it DC coupled. Or am I misunderstanding your question? (If so, how can I tell if the leak is DC or AC coupled?) | |
| May 29 at 19:30 | comment | added | Voltage Spike♦ | Is the leak DC or AC coupled? In something with a lot of enclosed metal, it will be really hard to stop capacitave coupling. | |
| May 29 at 19:05 | comment | added | Sandro | We can disconnect some sections of power (disconnecting connectors or unscrewing cables), which helps to narrow down the fault. | There is no problem in applying continuously 50V between earth and "0Vdc". But I still haven't found an easy way to find were the current is going. | The leak exists at DC (or at least at 0.25Hz), because the voltage between earth and +-50V remains during 2 seconds (and the displayed mesure is taken at the end of this period) | |
| May 29 at 17:34 | history | answered | Voltage Spike♦ | CC BY-SA 4.0 |