Correction Factors for Testing UTD Series DC MCCBs Using AC Test Equipment
The article contains the correction factors to be used when testing DC MCCB breakers with an AC test set, and when each factor applies.
1)
Overcurrent / Long Time Trip Testing
- Applies to Long Time and other overcurrent regions where the trip time is greater than 200 ms.
- In this region, the difference between AC and DC has minimal impact on breaker operation.
- An AC test set may be used directly, and a correction factor of 1.0 should be applied.
2)
Instantaneous Trip Testing
- Applies to the instantaneous trip region (trip time less than 200 ms).
- When performing DC instantaneous testing using AC equipment, a correction factor of 0.87 should be applied.
- This method is consistent with the testing approach used on the UTD production line.
Summary
- Long Time / Overcurrent testing → AC test set, correction factor = 1.0
- Instantaneous trip testing → AC test set, correction factor = 0.87
For
reference, I have also attached the installation and maintenance manuals.
Please refer to the installation manual for installation guidance, and
the maintenance manual for servicing and inspection procedures.