Online monitoring of transformer on-load regulator switches: OLTC condition assessment and fault warning

• Need for OLTC monitoring: The on-load tap-changer is the only mechanical component in the transformer that is actuated frequently, and each regulating operation carries with it mechanical wear and tear. oLTC failures are one of the most important causes of unplanned transformer shutdowns.
• Monitoring content: Tap changer operation counting, switching time monitoring, drive motor current monitoring, monitoring of dissolved gases and micro water in the oil
• fig. values (ethical, cultural etc): By monitoring trends in switching times and motor currents, it gives early warning of mechanical wear and tear before it leads to failure, upgrading OLTC maintenance from "by number of operations" to "by actual condition"."

1. Interpretation of monitoring parameters

1.1 Switching time-OLTC The completion time of each tap change is a central indicator of the condition of the mechanism. A gradual increase in switching time indicates jamming or wear of the mechanism. If the switching time changes abruptly or fluctuates abnormally, it should be checked immediately.

1.2 Drive motor current--The motor current reflects the mechanical load on the switching mechanism. A gradual increase in current represents an increase in resistance to the mechanism (poor lubrication, aging springs, etc.). Abnormal spikes in current may indicate a stall in one of the switching operations.

1.3 Gases in OLTC oil--The on-load regulator has a separate oil compartment, and the acetylene and hydrogen content of the oil reflects the strength of the switching arc and the degree of contact ablation.

2. Frequently Asked Questions FAQ

2.1 Q: Is OLTC monitoring and transformer body monitoring one system?

A: The monitoring objects are different - intrinsic monitoring looks at the inside of the transformer tank, OLTC monitoring looks at the mechanical action of the on-load switch. It is possible to access the same backend platform, but the front-end sensors and acquisition units are separate.

2.2 Q: Is the transformer needed without OLTC?

A: Unloaded regulator transformers do not have the need for frequent mechanical action and do not require OLTC monitoring. Only for on-load regulator transformers.

2.3 Q: How does OLTC monitoring data work?

A: The key is to establish a baseline for parameters such as switching time, motor current, etc., and subsequently compare the trend change of the baseline. Schedule maintenance when the trend accelerates and deteriorates, and you can extend the maintenance cycle when the trend stabilizes.

Disclaimer: The content of this article is for technical exchanges and reference only, and does not constitute any form of procurement commitment or contract offer. Product technical parameters, configuration programs and prices are subject to the actual signed contracts and technical agreements.

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