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Error Code - 6404 - Overcurrent (L1,L2,L3) Error


SMA CP-Series 6404 Fault Troubleshooting

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1. Notes:

1. Note 1: A CP-10 uses Semikron cubes and a list of compatible exchanges is provided in this report.

2. Note 2: The CP-US series inverter does not display blink codes and requires a data review to diagnose.

2. Visual References:

Figure 1 - Visual reference of Semikron stack

Figure 2 - Visual reference of the SMA Hummel stack

3. Fault Description and Likely Causes

SMA: Overcurrent Grid (HW) Overcurrent on the L1, L2 or L3 line conductors

This indicates that the SMA product has experienced a temporary or permanent fault in the path of the power stacks (SMA schematic reference: Cube 1 - T11, Cube 2 - T12, Cube 3 - T13).

1. SMA Cube Failure (reference “blink codes”)

i. All three stacks could fail at once

ii. One cube could fail alone while other two are not damaged (reference “compatibility”)

iii. One or more Semikron Driver boards could be the root cause

2. SMA Current Transducer (CT) Current Imbalance

i.It is possible for the main AC CT’s (SMA schematic reference: L1 – T30, L2 – T31, L3 – T32) to drift over time and drift can be accelerated by environments with high temperatures.

3. Possible External Event

i.In some cases, external grid events can create a temporary 6404 and cubes are undamaged. For this case, the inverter can be power cycled and returned to operation.

4. Catastrophic Capacitor Failure

i.SMA had a past quality issue with sine filter capacitors (SMA schematic reference: C1, C2, C3) that could catastrophically blow and collaterally damage other equipment in the inverter cabinet.

5. SC20CONT or Firmware

i.SMA SC20Cont (SMA schematic reference: A1) could fail in a manner that gives intermittent 6404 failures.

4. Troubleshooting

  1. Check the blink codes and use the article below to diagnose.
  2. Submit data for a review by the Solar Support team: HERE

5. Reference Material

1. Blink Codes – Semikron stacks have LED “Blink Codes” that can help identify the root cause in their systems. Full document SEMIKUBETM Board GB 11.

Figure 3 – Semikron LED Description 

Figure 4 – Semikron LED 0 Flash Pattern Explanation

Figure 5 – Semikron LED 2 and LED 3 Flash Pattern Explanations

2. Compatibility of Semikron stack types

6. Part Information

  1. For Semikron sets, please contact us for brand new cubes with warranties and training.
  2. For SMA Hummel Stacks, we can refurbish them! Ask us how.
  3. Also, we offer conversion packages to recover spare parts as assets for your project and replace your SMA Hummel cubes with Semikron for simplified diagnostics.

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