Protection CT vs Metering CT Selection
Engineering Intent
Protection CTs must reproduce fault current reliably, while metering CTs focus on measurement accuracy near normal load.
This article is written for engineers, EPC buyers and procurement teams who need to turn protection CT and metering CT into a clear technical request instead of a vague product inquiry.
Key Selection Data
| Item | Data to Confirm |
|---|---|
| Check 1 | Circuit purpose |
| Check 2 | Accuracy class |
| Check 3 | Rated burden |
| Check 4 | Fault current and relay requirement |
Standards and Evidence to Request
- IEC 61869
- Protection relay datasheet
- Metering accuracy requirement
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
- One CT specified for all functions without checking cores
- No protection class
- No relay burden information
RFQ Checklist
- State metering and protection cores separately
- Confirm ratio
- Provide class and burden
- Share relay model 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.
Download This Guide as PDF
Save this technical guide for offline reference. Includes all tables, specifications, and contact information.
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