SMA SB 1300TL Service Manual - Manual (Page 16)

Message Cause and corrective measure
Uzwk The internal hardware monitoring system has detected an overvolt-
age in the DC link of the inverter.
Corrective measures:
• If this message is displayed frequently, contact the
SMA Service Line.
Watchdog
Watchdog CCU Internal program run disturbance
Corrective measures:
• If this message is displayed frequently, contact the
SMA Service Line.
4.2 Red LED is Glowing Continuously
4.2.1 Procedure for Troubleshooting
If the red LED is continuously glowing during operation, there is a ground fault in the PV array or at
least one of the varistors for overvoltage protection is defective.
Procedure See
1. Check the PV array for ground faults. Section 4.2.2, page 16
2. If the red LED continues to glow, check
the function of the varistors. Section 4.2.3, page 19
4.2.2 Checking the PV System for Ground Faults
If the red LED is glowing and the inverter displays the message Riso or the communication product
displays the message Insulation error, there is a ground fault in the PV array. The electrical
insulation between the PV system and ground is defective or insufficient.
If the inverter displays the event numbers 3501, 3601 or 3701, there could be a ground fault. The
electrical insulation from the PV system to ground is defective or insufficient.
Danger to life due to electric shock
In the event of a ground fault, high voltages can be present.
• Touch the cables of the PV array on the insulation only.
• Do not touch any parts of the substructure or frame of the PV array.
• Do not connect PV strings with ground faults to the inverter.
Destruction of the measuring device due to overvoltage
• Only use measuring devices with a DC input voltage range of 600 V or higher.
4 Troubleshooting SMA Solar Technology AG
Service Manual SB13-21TL-SG-en-11 16