Fault condition upon arrival.

The Yaskawa Varispeed 616G5 CIMR-G5C4011 Spec.40111F was received with the report that the connected motor showed significantly different behavior in forward and reverse direction. In reverse direction, the motor jerked, ran unevenly, and reached a noticeably lower speed. In forward direction, the motor rotated considerably faster at the same reference value.

In addition, it was observed that the motor did not decelerate in a controlled manner during braking. The braking process was not completed properly. Instead, the motor continued running until the inverter shut down with the error “CF – Control Failure”.

This behavior occurred reproducibly and was independent of the mechanical load.

Initial technical assessment

Such asymmetrical behavior between forward and reverse operation usually does not indicate a mechanical problem. The motor itself showed no abnormalities during the initial inspection. Insulation values were within the specified range, and no phase faults or short circuits were detected.

The focus was therefore placed early on the internal control of the inverter, particularly on signal processing and the power channels. The Control Failure error indicates that the control system is no longer able to correctly process or track the actual values.

Diagnosis and findings

After opening the unit, a visual and electrical inspection of the relevant assemblies was carried out. Irregularities were found in the signal stability of individual channels of the power electronics. These deviations were not constant but depended on load and direction of rotation, which is typical for aged or drifting components within the control circuitry.

Such fault patterns are common in units that have been in continuous operation for many years. Aging of individual components causes the control system to operate asymmetrically. As a result, different torque behavior depending on direction of rotation and unstable braking processes occur.

Repair procedure

The unit was completely disassembled. The affected assemblies were selectively repaired. Faulty channels were reworked, and critical components susceptible to aging were replaced. In addition, preventive measures were carried out to ensure long-term stability of the control system.

After completion of the repair, the unit was reassembled and prepared for testing.

Functional test and result

The final test run was performed under defined conditions. The motor ran smoothly in both directions of rotation and reached the same speed at identical reference values. Acceleration and braking processes were stable and reproducible. The Control Failure error did not occur again.

The control system operated correctly, and the running behavior complied with the technical specifications of the unit.

Technical evaluation

The fault was caused by an issue in the internal control system that led to asymmetrical regulation. Such faults are not externally visible and, in many cases, can only be clearly identified through targeted measurements and experience with the specific device type.

Early repair in such cases prevents consequential damage to the motor, mechanics, or connected assemblies.

Conclusion

In the Yaskawa Varispeed 616G5 CIMR-G5C4011 Spec.40111F, differing behavior between forward and reverse operation can indicate internal control problems. If Control Failure errors also occur, the inverter should be inspected and repaired before further failures develop.

Further information such as price and delivery time for:
Yaskawa CIMR-G5C4011 Spec.40111F Varispeed 6161G5

More details about our Yaskawa repair expertise can be found here: Yaskawa Varispeed repairs by Industrypart

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Technical specifications

Functional description

The Varispeed 616G5 is a vector-controlled frequency inverter designed for demanding industrial applications. It enables precise speed and torque control of induction motors and is commonly used in machine tools and production systems. The internal control structure is based on multiple control channels, which can cause asymmetrical running behavior if aging or component drift occurs.

Typical application environments

• Machine tools
• Conveyor systems
• Machining centers
• Industrial systems with high demands on control stability

Alarm messages and notes

Note: Detailed alarm lists can be found in the original manual, alarm table on page 306.

Main components