Repair of the servo frequency inverter Lenze, series EVS-932X-ES

The EVS-9325-ES device is the more powerful “brother” of the EVS-9324-ES device.

PROBLEM:

When the device arrived at Promatis’ premises, the so-called diode test of the input and output connections was immediately performed using a multimeter. The device passed this test with flying colours, indicating that the output IGBT module itself was not affected by the error.

However, the client noted that the device was showing an OC1 error. OC1 (Overcurrent 1) indicates an error that cannot be corrected through software or by resetting the device.

This error means that the output overcurrent protection has been triggered, which in turn indicates that the output current measured by the current transformers on the U and V lines is significantly higher than the normal rated current (150% In).

SOLUTION:

 In that case, it is necessary to replace the current transformers on the U and V lines, labelled LA-25NP. These transformers can fail if, at some point, the current spiked (e.g., a short-term glitch) or due to age, affecting the transistor inside that uses the Hall effect. As a result, even when the current is normal, the device incorrectly reads it as excessively high, preventing normal operation.

After replacing the transformers and the electrolytic capacitors located around them, the device operates normally again.

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