De-Commissioning - Delta M42U Operation And Installation Manual

Maintenance

5.5 De-Commissioning

When necessary to remove the inverter from active operation for maintenance
or replacement, follow the instructions below.
To avoid serious injury, use follow the procedure
- Switch off internal AC switch and then both DC switches to cease inverter operation
- Switch off external AC circuit breaker or switch to disconnect the electrical grid from
the inverter chassis
- Remove array DC from chassis requires opening string level MC4 connectors in order
to break string continuity at the inverter MC4 connectors are not intended for use as a
load break switch, therefore:
Ensure inverter DC switches are open and there is no DC current flow
■ For -122 model –
Use MC4 tool to open and disconnect each string from the chassis mounted MC4
terminals at the inverter
■ For -120 model –
1. Within the connected array, open an MC4 connector within each string connected
to the inverter; repeat for strings connected to each MPPT input
2. Open WB by removing WB cover
3. For each MPPT channel,
• Use a voltmeter to check for zero voltage at the combiner output
• If any hazardous voltage level is detected, use voltmeter at the combiner input
(fuse holders) to measure voltage across each string.
• For any strings showing hazardous voltage, open external MC4 connectors in
those strings.
• Repeat measurements to insure there is no continuity in any connected string
• Loosen fuse holder screws to free string wiring and remove from wiring box
■ For -121 model –
1. For each MPPT channel
• Locate and open DC disconnect switch located at or within the associated array
combiner;
- if no switch is provisioned, open continuity of each string as described for -120
model, above
• Open inverter WB, and measure voltage across each MPPT input terminal pair
• Confirm there is no hazardous DC voltage at either input
2. Loosen fuse holder screws to free string wiring and remove from wiring box
■ RS-485 Communication module – all models
1. Remove communications module from inverter
2. Disconnect all communications wiring from the module terminals
3. Remove wiring from communications board assembly
4. Re-install communications board assembly in inverter
DANGER : ELECTRICAL HARZARD!!
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