SMA WB 5000A-11 Installation - Manual (Page 71)

SMA Solar Technology AG Troubleshooting
Installation Manual WB5A_6A-IA-IEN114540 71
9.3 Red LED Permanently On
If the red LED of the status display is continuously on during operation, there is either a ground fault
in the system or at least one of the varistors for the overvoltage protection is defective.
In deliberately grounded small wind turbine systems, the red LED has been on ever since the inverter
was commissioned. However, this has no impact on the function of the inverter. Before you check the
small wind turbine system for a ground fault, check whether deliberate grounding has been carried
out.
In deliberately grounded small wind turbine systems, check every so often that the varistors in the
inverter are working properly, since a varistor fault can no longer be displayed.
9.3.1 Checking the Small Wind Turbine System for a Ground Fault
1. Disconnect the inverter on both the DC and AC sides as described in Section 7.2 "Opening the
Inverter" (page 57).
2. Measure resistances between the phases and the ground potential:
– Measure resistance between L1 of the small wind turbine system and the ground potential,
and record value.
– Measure resistance between L2 of the small wind turbine system and the ground potential,
and record value.
– Measure resistance between L3 of the small wind turbine system and the ground potential,
and record value.
If the measured resistances are smaller than 10 Ω , there is a ground fault present in the small
wind turbine system. Eliminate the ground fault.
If the measured resistances tend towards infinity, there is no ground fault present in the small
wind turbine system and presumably the varistors are faulty.
– Check the function of the varistors as described in Section 9.3.2 "Checking the Function of
the Varistors" (page 72).
DANGER!
Risk of lethal electric shock
• Do not touch the small wind turbine system
• Only touch the insulation of the cables on the small wind turbine system.
• Do not touch PE.