REFU Elektronik GmbH
REFUsol 48K-UL
11
The inverter is connected to the DC photovoltaic array with two DC block terminal inputs rated for max.
1000 V.
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2.3.6
Grounding Requirements
Determine the appropriate grounding method with the responsible authority having jurisdiction.
System grounding, if required by Section 250 of the National Electrical Code, ANSI/NFPA 70, is the
responsibility of the installer.
The photovoltaic system grounding shall be installed per the requirements of Section 690.41 through
690.47 of the National Electrical Code, ANSI/NFPA 70, and is the responsibility of the installer.
Grounding the PV Modules
The PV frames require an equipment grounding conductor (EGC) per NEC requirements.
The inverter is a transformerless inverter. For this reason, it has no galvanic isolation. Neither the
positive (+) pole nor the negative ( ) pole of the modules connected to the inverter can be grounded.
Only the array frame/racking and modules frame must be grounded, or only the PV module frame
and racking must be grounded.
Insulation resistance detection (ground fault detection): Since the inverter is connected to
ungrounded PV arrays, it has an insulation resistance detection circuit that measures the DC
insulation resistance between the PV array inputs and earth ground prior to starting.
An Isolation Monitor Interrupter (IMI) is used to limit ground fault and backfeed current to the array
and the Protective Earth connection. This device limits shock hazards by restricting the ability of the
unit to connect to the grid when the system exceeds the limits stated in UL 1741. Additionally, the PV
array IMI monitors for ground fault current as required by UL 1741. If a ground fault occurs, the
inverter will shut off and will not restart until the fault has been cleared.
Grounding the AC Circuit
A protective earth feedthrough terminal block is available in the AC connection area. The gauge of the AC
grounding conductor must be sized in accordance with Table 250.122 of the NEC.
Important
Establish an AC ground connection to the protective earth ground (PE)
terminals before connecting to the grid.
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2.3.7
Heat Hazard
The cabinet surface and heat sink can reach temperatures up to 75 °C (167 °F).
WARNING
Risk of burn. The inverter components can become extremely hot during
normal operation.
Use caution when working around the heat sink area.
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