ac Generator Islanding

[Zokes]

NEC 690 has safety provisions for photovoltaic systems such that if the grid voltage is lost, the PV system must auto disconnect. This is to avoid a hazardous condition for someone trying to repair the grid. Is there a similar provision for ac generators which automatically start providing power locally during a power outage? It seems the same same condition would exist in both scenarios.
Thanks in advance.

 

[ron]

Re: ac Generator Islanding

You can parallel utility and generator with permission from the utility and compliance with Standard 1547-2003 IEEE Standard for Interconnecting Distributed Resources with Electric Power Systems.
http://shop.ieee.org/ieeestore/Product.aspx?product_no=SH95144

Lots of protective relay requirements.

 

[rcwilson]

Re: ac Generator Islanding

Solar power systems almost always operate in parallel with the utility, to sell power to the utility or offset a portion of the customer load. When the sun goes down, the transfer to utility power is seamless.

A standby generator is usually designed to only run during a power outage It is usually connected through a transfer switch that only allows the generator to connect to the load, not to the utility. If the generator does have paralleling switchgear, it will also have several protective relaying functions to protect the utility, including relaying to separate from the utility during a utility power outage.