Ground Fault Protection Device Datasheet

One of the main issues with other ground fault detecon/interrupon (GFDI) products is that these all
break the bond to the grounded conductor. When this occurs, not only is the earth bond compromised but
the baery and DC loads can also be le ungrounded and oang. For a negavely grounded system this
means that the negave side of the baery and loads can oat to negave Voc in relaon to ground and the
posive side can oat to (negave Voc + Vbat).
Sample Scenario: In the case of a 150V MPPT controller, this could introduce users to dangerous array
voltage from the DC loads-to-ground, which could cause a personal safety hazard. It is also possible that
with these other GFDI soluons, the newly introduced higher voltage scenario could create a DC (load-side)
spark safety hazard.
Other ground fault detecon interrupon soluons are inferior because:
• They break the earth bond.
• A 1A fuse in bond creates a very unstable earth bond.
• Others soluons do not isolate the normally grounded conductor of the faulted circuit.
• Normally grounded components (more conductors, baery and DC loads) can oat to a potenal
dierent from ground (negave Voc levels).
• This creates a safety hazard, and as such requires a second Ground Fault Warning Label at the
baery bank.
• Their fuses must be replaced.
• Fuses are crude. They do not blow at precise currents and replacements are oen unavailable at
remote sites.
• They are not ideal for PV systems with mulple controllers. If they are used in systems with mulple
controllers, then the following may occur:
• Only one earth bond means that all controllers in the system will disconnect during a ground fault,
thus causing solar charging to cease.
• Only one earth bond means that the number of controllers that can be connected to a baery bank
is limited to the number of ganged breakers in a GFDI.
• Some GFDIs may be set up to disconnect the inverter and/or DC load(s) for added protecon from
oang voltages, thus causing loads to shut down.
Illustraon: Why Other Ground Fault Protecon Device Soluons Are Inferior