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


SMA CP-Series 6404 Fault Troubleshooting

Having a problem? We can help. Submit your SD card data HERE.

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 therefore cannot be self-diagnosed in the field. This                 unit requires a data review to diagnose, contact us for support.

a. The SMA CP-US Hummel cubes can be replaced with a Semikron set. Contact us for procedures so we can get your unit back online.

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. Always perform a detailed visual inspection of the stacks when addressing a 6404 fault. Check for arcing from the capacitors to the chasis, debris underneath the stacks, and for any visual signs of overheating.
  2. Check the blink codes and use the article below to diagnose.
  3. Submit data for a review by the Solar Support team: HERE
  4. For the CP-US inverter, it can only be diagnosed using the SMA data packets.

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 - Semikron strongly recommends only operating Semikubes in matching sets for best performance and reliablility.

Due to their recommendation, we are only able to accept stack sets for refurbishment which are a complete matching set. If cubes have been mixed during the warranty period, we'd recommend storing the set until you're able to obtain 3 kubes for a full matching set. 

Is this too confusing? Don't hesitate to reach out and we'll help make sure you've got the correct configuration before shipping.

Figure 6 - Semikron compatibility chart and identification process

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. We also carry limited amounts in stock.
  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.

7. Refurbishment of Semikron Products.

Be sure to reference Figure 6 to ensure your set is a complete matching set.

Inspect your set using the following guidelines to ensure it's a candidate for refurbishment. As always, don't hesitate to reach out to our team for an opinion.

Figure 7 - Initial evaluation of Semikron stacks for refurbishment

Figure 8 - Evaluating moderate damage for Semikron refurbishment

Figure 9 - Evaluating heavy damage which will likely result in a full-cost Semikron refurbishment

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