What Can Nameplate Information Tell Us About the Performance of a 20 kV Vacuum Circuit Breaker (VCB)?
When selecting or inspecting a 20 kV Vacuum Circuit Breaker (VCB), the nameplate provides essential information about its performance and operating conditions. A typical 1250 A VCB nameplate includes the following parameters:
Rated Voltage: 24 kV
Although the system voltage is 20 kV, the VCB is rated at 24 kV to provide insulation margin and ensure safe operation.
Rated Current: 1250 A
Indicates the breaker can continuously carry 1250 A without overheating.
Rated Frequency: 50 Hz
Suitable for 50 Hz power systems, compliant with medium-voltage distribution standards.
Rated Short-circuit Breaking Current: 25 kA / 3 s
The breaker can withstand a maximum short-circuit current of 25 kA and safely interrupt it within 3 seconds, protecting the electrical system.
Rated Operating Sequence: O-0.3s-CO-3min-CO
Specifies the breaker’s operation cycle: Open – Close (0.3 s) – Open – 3-minute rest – Close again, ensuring fast operation and load adaptability.
Rated Withstand Voltage: 50/125 kV
Includes power-frequency AC withstand voltage 50 kV and lightning impulse withstand voltage 125 kV, verifying insulation strength.
Closing Coil Voltage: AC/DC 100 ~ 125 V
Ensures the closing coil matches the control power for reliable operation.
Opening Coil Voltage: DC 100 ~ 125 V
Ensures the opening coil voltage is compatible with the control source, enabling safe breaker interruption.
Understanding these nameplate parameters helps engineers correctly select, install, and operate a VCB, improving system safety and reliability. The nameplate serves not only as the breaker’s “ID card” but also as a key reference for performance and compatibility.
Vacuum Circuit Breaker Timer & Analyzer(JYK-II)
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Hazards and Treatment of Excessive Contact Resistance of Circuit Breakers or HV Switches
How to measure the contact resistance without changing the circuit?
How to Correctly Test the Contact Resistance of HV Switchgear or Circuit Breaker?
Why Does Excessive Contact Resistance Occur In Electrical Secondary Circuits?
What is the Testing Checklist for 110kV/220kV Substation Acceptance and Maintenance Testing?
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