Transformer seal loss

On SMA Sunny Central CP XT central inverters, transformer seal loss shows up as error 6440. The error means the medium-voltage transformer is no longer hermetically sealed. The manufacturer's corrective measure for this error is to inspect the MV transformer. When you inspect the inside of the transformer, check that the sealing strip is properly fixed. Take an oil sample at the oil leakage port and have it analysed to judge the transformer's operating condition. Regular periodic inspection helps catch abnormal transformer conditions before the damage grows. This matters because taking a transformer out of service causes considerable production losses.