Why is CT placed after breaker?
1. Safety:
Placing the CT after the breaker ensures that the CT can be safely isolated when the breaker is open, reducing risks during maintenance or replacement.
2. Protection of CT:
The breaker protects the CT from overcurrents and short circuits, extending its lifespan.
3. Accurate Measurement:
This placement allows the CT to measure the actual current flowing to the load, including any current drawn by equipment connected after the breaker.
4. Selective Measurement:
It measures only the current in the specific circuit protected by that breaker, allowing for more precise monitoring and control.
5. Compliance:
Many electrical codes and standards require CTs to be placed after breakers for safety and accuracy reasons.
6. Ease of Maintenance:
This arrangement allows for easier CT replacement or maintenance without affecting the main power supply.
7. Coordination with Protection Schemes:
It ensures that the current measurement aligns with the breaker's protection function.
8. Avoid Nuisance Tripping:
Placing the CT after the breaker prevents it from detecting inrush currents during breaker closing, which could cause false readings or unnecessary tripping.
9. Flexibility:
It allows for the addition or modification of CTs without necessarily changing the main breaker arrangement.
This configuration is standard practice in most electrical systems to ensure safety, accuracy, and proper system operation. However, specific applications may have variations based on particular requirements or constraints.
