Installation and Operation Manual (Rev E)
SGI Series Inverters
DOCR-060371
24
4.4
DC Ground Fault Detection and Interruption
Every SGI inverter is equipped with an automatic DC Ground Fault Detection and Interruption
(GFDI) circuit. When a single ground fault on an ungrounded circuit exceeding the pickup value
is present in the PV array or in the DC wiring to the inverter, the DC GDFI breaker will trip and a
ground fault will be signaled by means of a yellow LED and a message on the front LCD display.
Breaker TRIPPED
DC GROUND FAULT INDICATED
Breaker ON
NO GROUND FAULT DETECTED
Figure 4.3 – Operating Positions of GFDI Breaker
DC Ground Fault Current Pickup
Maximum Trip Time
SGI 225/250
4 A
1 s
SGI 266/300/500PE/ 500
5 A
1 s
Table 4.5 – DC GFDI Specifications
WARNING:
In the event of a ground fault, DO NOT TOUCH any equipment (including,
but not limited to: the inverter, the PV array disconnects, the PV array combiners, the
PV panels, the PV racking system). Immediately contact the installer or another
qualified person to locate and repair the source of the ground fault. Be aware that
normally grounded conductors and equipment may be energized and may pose a
significant shock and / or fire hazard.
WARNING:
If the GFDI breaker trips upon connection of one or more combined
strings, a ground fault in the array must be located and eliminated before proceeding.
The DC ground fault is eliminated when the GFDI breaker can be engaged into its
lever-up position and remain in that position. Failure to obey these instructions may
cause the grounded conductor to rise to potentially unsafe voltage levels.
WARNING:
Even when the DC disconnect is in the off position, the ungrounded DC
conductor leading up to the DC disconnect will remain live on the PV side as long as
the PV modules are in daylight. The inverter side of the DC disconnect will also remain
live after the disconnect has been shut off until 60 seconds after the LEDs turn off, as
DC bus capacitors in the inverter discharge.
