CT secondary burden
Compare complete lead-loop and connected device burden with the CT rated burden.
Enable JavaScript for live calculations. Read the method and default example below.
Method and assumptions
- Lead VA = secondary current² × complete lead-loop resistance. Total external VA = lead VA + device VA.
- Loop resistance includes outgoing and return leads. CT winding resistance is excluded.
Before using the result
- This budget does not verify accuracy, saturation, protection class or performance at the actual operating burden.
- Never open an energised CT secondary. Use an approved shorting and test arrangement.
Worked example
Illustrative default inputs. Enter your project values above.
- CT secondary current
- 5 A
- Complete lead-loop resistance
- 0.113 Ω
- Connected device burden
- 0.5 VA
- CT rated burden
- 5 VA
Default results
- Lead burden
- 2.825 VA
- Total external burden
- 3.325 VA
- Rated burden used
- 66.5 %
Choose a reference or send your BOQ
Compare relevant product families, then confirm the exact rating, control supply and duty. Price and availability are confirmed with your enquiry.
Technical references
These references support planning. The exact model documentation and a project-specific engineering review govern the final specification.