What Is the Difference Between the Ratio on the Current Transformer and the Ratio on the Watt-Hour Meter?

1. Differences in use

If the transformation ratio of the current transformer is inconsistent with the transformation ratio of the ammeter, the displayed value of the ammeter cannot be used directly and must be scaled.

If the transformer with a ratio of 5 is used on a meter with a ratio of 1, the secondary current of the CT will generally exceed 1A, which will cause the meter with a ratio of 1 to exceed the range and damage the ammeter.

2. Difference accuracy

If the transformer of ratio 1 is used on the meter of ratio 5, since the secondary current of the CT is less than 1A, the measurement accuracy of the ammeter of ratio 5 will be greatly reduced.

The 800/5 ammeter is broken, and the 300/5 ammeter can be used as a temporary substitute. However, the measured results must be scaled.

3、Relay protection requirements difference

* The short-circuit capacity at the outlet of the circuit breaker remains unchanged under the maximum and minimum operating modes.

* The current transformer is a two-phase incomplete star connection.

* GL-11 type overcurrent relay is used for overload and quick-break protection.

* The operating power supply is DC 220V, and the circuit breaker opening form is shunt tripping.