ABB Vacuum Contactor KC2 Power Supply System Technical Transformation Plan

Issue Overview​
The 10kV air compressor starting system of a company utilizes the ABB vacuum contactor KC2 as the control component for the operating circuit. The dedicated wide-voltage power supply module paired with this contactor presents the following issues:

1. ​Frequent failures: The power supply module fails to properly transition the voltage from 300V to 12V, resulting in fuse blowouts.
2. ​Poor heat dissipation: Enclosed installation of the module leads to insufficient heat dissipation, accelerating component aging.
3. ​High costs: The original module costs approximately 5,000 RMB per unit, leading to excessive maintenance expenses.

​II. WONE Technical Transformation Plan​
​Core Approach: Adopt a "functional decomposition" strategy to separate the contactor’s pull-in and holding functions, each powered by different sources.

​System Composition:

1. ​Original power supply module: Handles only the instantaneous pull-in function, outputting 300V DC to drive the contactor pull-in.
2. ​New 12V power supply module: Manages the long-term holding function, providing the maintaining current to the contactor coil after pull-in.
3. ​Control relay: Enables automatic control of power switching after pull-in completion.
4. ​Isolation diode: Prevents interference between different power sources.

​Working Principle:

• During startup, the original module outputs 300V DC to instantly pull in the contactor.
• After the contactor pulls in, the auxiliary contact activates the control relay.
• Once the control relay operates, it cuts off the original module’s power supply circuit and simultaneously connects the 12V holding power supply.
• The 12V power supply provides maintaining current to the contactor coil, ensuring normal operation.

​III. Implementation Plan​
​Equipment List:

​Installation Requirements:

1. The 12V power supply module should be installed in a well-ventilated location outside the cabinet.
2. All wiring must comply with electrical installation standards.
3. Newly added components should be fixed with brackets to ensure secure installation.

​IV. Advantages of the Plan​

1. ​Cost-effectiveness: The total transformation cost is approximately 160 RMB, significantly lower than the 5,000 RMB original module.
2. ​Reliability:
• The original module’s operation changes from continuous to instantaneous, significantly extending its lifespan.
• The 12V power supply module is a standard industrial component, highly reliable and easy to replace.
3. ​Maintainability: The newly added module is installed in a location convenient for maintenance, allowing simple and quick replacements.
4. ​Safety: Electrical isolation ensures safe system operation.
5. ​Proven effectiveness: Similar transformations have been operating stably for two years, with significant results.

​V. Implementation Results​
This plan thoroughly resolves the original design flaws through technical innovation, achieving:

• Equipment failure rate reduced by over 90%.
• Annual maintenance costs reduced by more than 80%.
• Equipment availability increased to 99.5%.
• Maintenance response time shortened from several days to a few hours.