A friend of mine asked me to look at here PV system as she is not getting any power (and thus money) from it. First real issue is the Aurora inverter has a E031 fault which I suspect is burnt out relays, so I can probably fix that with a big iron and a couple of new relays (at last for another few years).
Other problem she reports is the RCD feeding it frequently trips. It is a 30mA type AC RCD and unfortunately I could not measure the real operating leakage, etc, as the inverter is borked, so I only saw around 0.4mA in its standby/testing IR mode. DC IR results look sane, over 200M for cable and around 10M with the inverter's AC isolator closed.
It is fed via SWA but nobody has bothered to earth the armour deliberately, though far end is in contact with the metal enclosure - sort of!
So I was wondering why it had a 30mA RCD, and on looking at the manual it actually says:
In accordance with article 712.413.1.1.1.2 of Section 712 of IEC Standard 64-8/7, we hereby declare that, because of their construction, ABB inverters do not inject ground fault direct currents.
The use of an AC type circuit breaker with differential thermal magnetic protection with tripping current of 300 mA is advisable so as to prevent false tripping, due to the normal capacitive leakage current of photovoltaic modules.
On the case of systems consisting of multiple inverters connected to a single switch with differential protection, it is recommended to install a device that allows the adjustment of the trip value and timing of intervention.
So my thoughts are to change the 30mA unit to a 300mA delay version and type AC are fairly cheap (as in £60-ish), and to add some SPD as well, so hopefully no more nuisance trips. Now the latest regs say not to use a type AC if there is any risk of DC, but here:
TL;DR use the depreciated type AC if manufacturer say OK?
Other problem she reports is the RCD feeding it frequently trips. It is a 30mA type AC RCD and unfortunately I could not measure the real operating leakage, etc, as the inverter is borked, so I only saw around 0.4mA in its standby/testing IR mode. DC IR results look sane, over 200M for cable and around 10M with the inverter's AC isolator closed.
It is fed via SWA but nobody has bothered to earth the armour deliberately, though far end is in contact with the metal enclosure - sort of!
So I was wondering why it had a 30mA RCD, and on looking at the manual it actually says:
In accordance with article 712.413.1.1.1.2 of Section 712 of IEC Standard 64-8/7, we hereby declare that, because of their construction, ABB inverters do not inject ground fault direct currents.
The use of an AC type circuit breaker with differential thermal magnetic protection with tripping current of 300 mA is advisable so as to prevent false tripping, due to the normal capacitive leakage current of photovoltaic modules.
On the case of systems consisting of multiple inverters connected to a single switch with differential protection, it is recommended to install a device that allows the adjustment of the trip value and timing of intervention.
So my thoughts are to change the 30mA unit to a 300mA delay version and type AC are fairly cheap (as in £60-ish), and to add some SPD as well, so hopefully no more nuisance trips. Now the latest regs say not to use a type AC if there is any risk of DC, but here:
- It is not even obvious if RCD is needed, given the SWA cable and fixed connections.
- The manufacturer's instructions explicitly say type AC is OK
TL;DR use the depreciated type AC if manufacturer say OK?
![[ElectriciansForums.net] Type AC RCD with solar inverter](https://electricians.s3.eu-west-1.amazonaws.com/data/attachments/65/65117-7aca69a1b2e9568626705784d443140b.jpg "[ElectriciansForums.net] Type AC RCD with solar inverter")
