Schneider Electric DC protection offering for PV solar installations

With the IEC-compliant additions to its Compact NSX and Acti 9 circuit breaker and switch disconnector ranges for photovoltaic installations, Schneider Electric now offers comprehensive DC-side protection.

Malaysia, 13th July 2012 – Schneider Electric is pleased to announce the release of IEC extensions for its Compact NSXTM and Acti 9TM ranges to meet the special high-performance requirements of photovoltaic (PV) systems. The releases highlight the company’s ability to think out of the box when designing DC-side protection devices for PV solar generation, where the principles that underpin the configuration of classic grid-connected AC installations do not apply.

“A PV solar installation generates variable DC output from multiple sources – solar modules arranged in arrays – which requires special disconnects to isolate components”, says Mok Kam Meng, Energy Efficiency Manager, Services & Project Division of Schneider Electric Malaysia.

“What’s more, its short-circuit current is limited, so overcurrent protective devices need to operate at low fault currents. Protection and control devices to operate in a PV installation need to be designed to meet these and other specific requirements of these highly-demanding systems.”

The extensions to the Compact NSX and Acti 9 ranges address specific safety issues.
PV generator and array boxes are housed outdoors where exposure to sunlight and poor ventilation can lead to high temperature working environments. Injuries caused by burns from protective devices have been reported. Furthermore, maintenance and servicing work cannot be carried out in daylight, when solar panels are active, so it is critical to pre-empt any malfunction or incident that might cause a loss of downtime.

It is also far more demanding to open a DC circuit in PV installations as the current is always non-zero. Protective devices should therefore be carefully designed and dimensioned to trip up to a system’s maximum open circuit voltage.

An additional fire hazard associated with PV systems is the risk of double earth faults occurring. As the fault spreads it causes a DC fault arc, which does not self-extinguish even at low currents.

Extensions with extended protection capacities
Schneider Electric’s R&D teams have harnessed their know-how to deliver a now comprehensive IEC-compliant DC protection range that meets the critical standards of PV installations.
Compact NSX DC PV molded case circuit breakers up to 1000V DC are fully consistent with earlier products and accessories in the range. To avoid oversized components and any risk of overheating inside enclosures their ratings have been optimized and upstream jumpers with heat stinks are supplied as standard. And derating tables ensure proper installation in array boxes. The shunt-trip breaker can also be used to remotely trip breakers and ensure the safety of firefighters.

Schneider Electric has also strengthened its classic Acti 9 range offering with the C60 PV modular circuit breakers, C60NA DC and SW60 DC switch disconnectors. The C60 devices boast increased protection capacities – respectively up to 800V DC and 1000V DC for small and large buildings applications. They ensure fully reliable circuit breaking protection and fault isolation for PV strings and wiring. For ease and safety of installation, they come prewired.

Schneider Electric has long boasted a comprehensive proven AC protection offering. It has now done the same on the DC side, so paving the way for solar PV technology to be as safe and reliable as it is green and clean.

Visit www.schneider-electric.com/solar and download the FREE “Safe and reliable photovoltaic energy generation” application guide to learn more.