The main difference between a Current Transformer (CT) and a Potential Transformer (PT), also known as a Voltage Transformer, lies in their function: a CT measures current, while a PT measures voltage. Both are crucial for ensuring the accuracy and safety of power systems.
Understanding CTs and PTs
Both CTs and PTs are measuring devices designed to step down high electrical quantities to levels that can be safely and accurately measured by instruments.
Key Differences Between CT and PT
Here's a detailed comparison:
| Feature | Current Transformer (CT) | Potential Transformer (PT) (Voltage Transformer) |
|---|---|---|
| Function | Measures high current by stepping it down. | Measures high voltage by stepping it down. |
| Purpose | To provide a reduced current signal for metering and protection. | To provide a reduced voltage signal for metering and protection. |
| Measurement | Current | Voltage |
| Signal Level | Low current | Low voltage |
How They Work (Based on Reference)
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CT (Current Transformer): A CT lowers the current signals for measurement purposes. It transforms a large primary current into a smaller, measurable secondary current.
-
PT (Potential Transformer): A PT lowers high voltage values into lower ones that can be safely measured. It transforms high primary voltage into a smaller, measurable secondary voltage.
Applications
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CT Applications:
- Metering high currents in transmission lines.
- Protecting equipment from overcurrent conditions.
- Used in conjunction with ammeters, relays, and other protective devices.
-
PT Applications:
- Metering high voltages in transmission lines.
- Protecting equipment from overvoltage conditions.
- Used in conjunction with voltmeters, relays, and other protective devices.
