Electrical Connection To The Pv Field - Dc Side - ABB UNO-DM-TL-PLUS-US Product Manual

E
lectrical connection to the PV field - DC side
Confirm the correct polarity in the input strings.
Confirm there is no ground leakage current in the PV array.
When exposed to sunlight, the PV panels supply DC direct voltage to the inverter.
The inverter's DC switch disconnects the DC current from the PV panels. In the "OFF" posi-
tion the inverter will stop producing power, but DOES NOT disconnect the AC from the grid.
To prevent electrocution hazards, all the connection operations must be carried out with the
external AC disconnect switch, downstream of the inverter (grid side), open and locked out.
The transformerless design requires that the PV array to be floating with respect to ground
per NEC 690.35.
DC PV string wire must be UL-listed wire per NEC 690.35 with rated minimum 600V.
PV output conductors (wiring) must consist of sheathed (jacketed) multi-conductor cables or
single insulated conductors (wires) which must be installed in an approved raceway. These
conductors must be isolated from the enclosure and system grounding, as required by NEC
690.35. This is the responsibility of the installer.
Confirm that the maximum PV array short circuit current for each DC input channel is within
the inverter specification. Array equipment grounding must be installed per the requirements
of the NEC and is the responsibility of the installer. A configuration program that can help to
correctly size the photovoltaic system is available on at http://www.stringsizer.abb.com.
Conduit must be sealed using water-tight fittings to maintain NEMA Type 4X enclosure integrity.
After having carried out preliminary checks and therefore having verified
that there are no problems in the photovoltaic system, and the channel
configuration has been selected (parallel or independent) you may con-
nect the inputs to the inverter.
- Turn the DC switch OFF
- Loosen the four captive screws on the wiring box cover (Torx 20) and
remove the cover
- Remove the threaded plastic plug and nut from the DC cable opening
- Insert the appropriate water-tight conduit connector and tighten to the
chassis to maintain NEMA 4X compliance.
- Run the DC wires through the openings dedicated to the DC conduit.
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5 - Installation
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