forresthuynh
Member
- Location
- Carrboro, NC USA
I work in utility scale solar and have observed the following situation frequently on both new and old sites and need clarity on how, why, and any safety procedures related to the topic:
Situation
After opening the disconnect switch on an array level combiner box (and thus breaking the circuit from the inverter aka load) I have amp clamped the module series string input conductors going into the combiner box and observed currents ranging from low values (1-2A) to full array IMP. This current is present while the combiner box input fuses are closed in (the fuses are non-load break rated), but coworkers have confirmed that opening them will not draw an arc and will make the current disappear via the meter.
I have heard that "differential voltage potential" is the cause of this presence of current on an open circuit. The thought being that if different voltages are present (from broken/defective modules, soiling, ect) on the combiner box input strings, a circuit can develop in the module series strings that have higher or lower voltages.
Note: I always zero my meter before amp clamping, this occurrence has been seen with the inverter/DC Recombiner/CB open, ground faults were not present on these occurrences.
Can this situation please be clarified for me?
thanks,
Situation
After opening the disconnect switch on an array level combiner box (and thus breaking the circuit from the inverter aka load) I have amp clamped the module series string input conductors going into the combiner box and observed currents ranging from low values (1-2A) to full array IMP. This current is present while the combiner box input fuses are closed in (the fuses are non-load break rated), but coworkers have confirmed that opening them will not draw an arc and will make the current disappear via the meter.
I have heard that "differential voltage potential" is the cause of this presence of current on an open circuit. The thought being that if different voltages are present (from broken/defective modules, soiling, ect) on the combiner box input strings, a circuit can develop in the module series strings that have higher or lower voltages.
Note: I always zero my meter before amp clamping, this occurrence has been seen with the inverter/DC Recombiner/CB open, ground faults were not present on these occurrences.
Can this situation please be clarified for me?
thanks,