Working very closely with our clients, we covered the whole spectrum of original oil circuit breaker ratings. Particular attention was given to the enhanced fault making requirements of the original applications where on site generation and large motor drives are utilised. Most modern vacuum circuit breakers achieve dc component levels of typically 30%. Recognising the fact that the original oil circuit breakers were tested to BS116 at dc component levels of 53%, we conducted supplementary tests at 45%dc component levels to ensure maximum compatibility with the original oil circuit breakers.
The new 800A and 2000A 12 kV vacuum circuit breakers have undergone a very rigorous testing regime and have been fully certified by KEMA at the following ratings:
- 40kA short time current (3 secs) and symmetrical breaking capacity
- 110kA dynamic withstand and peak making capacity (actually achieving in excess of 120kA on test)
- 45% dc component
- 50hz and 60hz short circuit testing conducted (no assigned frequency rating)
The vcb has also been certified as an earthing truck for the double busbar VTD range, achieving 2 x Close onto fault operations at the enhanced peak current of 110kA. Due to one particular clients application, Switchgear Support Ltd have also certified the vacuum circuit breaker at an increased voltage level of 15kV, with a 31.5kA, 60hz rating.
This new range of vacuum circuit breakers may also allow the original switchboard to be safely and justifiably rerated in terms of its fault level, i.e, enhance making capability, fault level increases from 26.3kA to in excess of 30kA. Contact Switchgear Support Ltd for further details.
With Switchgear Support Ltd’s comprehensive knowledge of the VSI and VTD range of switchgear and our knowledge of over 5,000 VSI/VTD retrofits, we can guarantee the correct application of our vacuum circuit breakers in meeting all of your requirements. For 1250A (R12/3 oil circuit breaker) applications, please contact Switchgear Support Ltd.