CT Accuracy Class 0.5 vs 5P Explained
Engineering Intent
Metering CTs and protection CTs use different accuracy classes, so 0.5 and 5P should not be treated as interchangeable.
This article is written for engineers, EPC buyers and procurement teams who need to turn CT accuracy class into a clear technical request instead of a vague product inquiry.
Key Selection Data
| Item | Data to Confirm |
|---|---|
| Check 1 | Metering or protection circuit |
| Check 2 | Accuracy class |
| Check 3 | Rated burden |
| Check 4 | Relay fault current requirement |
Standards and Evidence to Request
- IEC 61869 accuracy class definitions
- Meter or relay datasheet
- Protection study
For project approval, request a technical datasheet, outline drawing, wiring or terminal diagram where applicable, routine test report and nameplate information before shipment.
Common Specification Mistakes
- Using metering CT for protection duty
- No ALF or protection class information
- No burden value
RFQ Checklist
- State circuit purpose
- Confirm accuracy class
- Provide burden
- Attach relay or meter data if available
Related Product Paths
Ziyao Power can review the single-line diagram, load schedule, panel drawing or tender sheet and convert the requirement into a practical quotation package.
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