L8 And L9 Trip Curves And Trip Times On DC Applications
Question:
- Are there trip curves and documentation for trip times when using L8 UL1077 supplemental protectors or L9 circuit breakers in DC applications?
Answer:
When using these products on DC applications or DC loads, refer to the published trip curves and times for AC applications as show in the current catalog or the UL Application Guide. Use a factor of 1.5 for the magnetic instantaneous trip X the continuous current rating (In).
The thermal trip times remain the same for both AC and DC applications. Refer to the table to calculate trip times for DC applications.
| L8 Supplemental Protectors Instantaneous Trip Times | multiple for AC Current (I/In) | becomes | multiple for DC Current (I/In) |
|---|---|---|---|
| B Trip Curve | 3 to 5 | 4.5 to 7.5 | |
| C Trip Curve | 5 to 10 | 7.5 to 15 | |
| D Trip Curve | 10 to 20 | 15 to 30 |
| L9 Circuit Breaker Instantaneous Trip Times | multiple for AC Current (I/In) | becomes | multiple for DC Current (I/In) |
|---|---|---|---|
| C Trip Curve | 5 to 10 | 7.5 to 15 | |
| D Trip Curve | 10 to 20 | 15 to 30 |
For additional information please contact your nearest authorized distributor, sales representative, or call our customer service or technical support lines.
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