PV and Back up Generators

[mark the spark2]

Hi I don't know if anyone can help but I was wondering if anyone has come up with any solutions to this problem. In that we have a 210kw pv system connected to the mains panel at a big office block and they have a back up generator with auto change over fitted so when the grid fails the Generator cuts in. Obviously we then have the problem that the inverter (X 9of) will switch off when grid is lost but would then switch back on when generator is running but if this happens at the weekend for instance or when there is not much load on then the inverters would try to feed into the generator causing god knows what problems. By the way the PV connection point is about 150 mtr from the generator change over panel. Any help much appreciated.

 

[SibertSolar]

Is there an external G59 relay fitted? If yes, could you wire an interlock signal from the genny (or CO switch) into the relay's contactor coil feed circuit? That's a common way of doing it

 

[mark the spark2]

Is there an external G59 relay fitted? If yes, could you wire an interlock signal from the genny (or CO switch) into the relay's contactor coil feed circuit? That's a common way of doing it

Thanks for your help. Unfortunately we didn't need to fit one on this site the DNO are getting more relaxed about them.(sods law really as normally we do build and fit them). I think it will have to be a contactor with the coil being fed from the generator feed so that when it kicks in it knocks the contactor out and there by killing the PV system?

 

[Leesparkykent]

Thanks for your help. Unfortunately we didn't need to fit one on this site the DNO are getting more relaxed about them.(sods law really as normally we do build and fit them). I think it will have to be a contactor with the coil being fed from the generator feed so that when it kicks in it knocks the contactor out and there by killing the PV system?

Or an mccb with auxiliary contacts for shunt trip.

 

[mark the spark2]

Or an mccb with auxiliary contacts for shunt trip.

Thanks. I am not familiar with shunt trips could you explain how they work or what they do? Thanks again

 

[Leesparkykent]

Thanks. I am not familiar with shunt trips could you explain how they work or what they do? Thanks again

A shunt trip device can be an optional accessory in a mccb that mechanically trips the mccb when power is applied to the shunt trip terminals. The power for the shunt trip does not come from within the mccb, so it must be supplied from an external source (in this case maybe one of the neons on the change over switch)Some MCCBs allow field installlation of a shunt trip kit, however others require factory installation when it's ordered. Check the specific type for available shunt trip voltage ratings and for the method of installation.

http://www.protekuk.co.uk/mccb-data-sheet.pdf

 

[mark the spark2]

A shunt trip device can be an optional accessory in a mccb that mechanically trips the mccb when power is applied to the shunt trip terminals. The power for the shunt trip does not come from within the mccb, so it must be supplied from an external source (in this case maybe one of the neons on the change over switch)Some MCCBs allow field installlation of a shunt trip kit, however others require factory installation when it's ordered. Check the specific type for available shunt trip voltage ratings and for the method of installation.

http://www.protekuk.co.uk/mccb-data-sheet.pdf

Wow thanks that sounds interesting. I will see what is available for our MCCB main switch. Thanks

 

[Worcester]

If you use a shunt trip, presumably the MCCB would need a manual reset?

Whilst G59 relay / contactor would be automatic reset when genny off ?

 

[davesparks]

If you use a shunt trip, presumably the MCCB would need a manual reset?

Whilst G59 relay / contactor would be automatic reset when genny off ?

Not necessarily, you could install a motorised closing mechanism to go with it for ££££££

 

[Gavin A]

it'd be useful to know what inverters you've used. I think both SMA and ABB would have control options that could be used to sort this out.

 

[SibertSolar]

That's a soft input though isn't it Gavin? Resulting in an active but zero power state? Wouldn't an (electro)mechanical interlock be ideally required/preferred?

 

[mark the spark2]

Thanks for comments. The inverters are Fronius Symo.

 

[Gavin A]

That's a soft input though isn't it Gavin? Resulting in an active but zero power state? Wouldn't an (electro)mechanical interlock be ideally required/preferred?

it'd still achieve the same thing though really. Ultimately the G59 settings should stop anything massively bad happening, but it'd not be a good situation to be in for long.

No idea about fronius though.