Differences in wiring methods between 3P3W and 3P4W in electric meters
In electric meters, 3P3W (three-phase three-wire) and 3P4W (three-phase four-wire) are two common wiring methods. The main difference between them lies in whether they include a naught wire. The following will introduce in detail their features, type wiring methods, and the method to change 3P4W to 3P3W for deal with current imbalance.
1. 3P3W (three-phase three-wire) electric meter
Features:
- Three phase conductors, No need naught wire.
- Suitable for three-phase load balancing scenarios.
Types wiring for 3P3W line
2. 3P4W (three-phase four-wire) electricity meter
Features:
- Three phase conductors and one naught wire, for a total of four conductors.
- Suitable for unbalanced three-phase load scenarios.
Types wiring for 3P4W line
Method to change 3P4W wiring method to 3P3W to deal with current imbalance
During the operation of the power system, the current imbalance caused by different loads may require changing the wiring method of the meter, from 3P4W (three-phase four-wire) to 3P3W (three-phase three-wire). This process involves connecting the conductors of phase B with the naught wire to accommodate current imbalances and improve measurement accuracy.
Overview of 3P3W wiring method:
Compared with 3P4W, the 3P3W wiring method does not have a naught wire. This wiring method is usually used in situations where the load is more balanced. The steps to change the wiring method are as follows:
Step 1. Connect phase B with naught wire: Connect the B-phase wire originally connected to the meter with naught wire.
Step 2. Reconnect the A, B, and C phase wires: Connect the A, B, and C phase wires to the corresponding input terminals of the meter respectively.
Step 3. Verify the phase sequence: Make sure the phase sequence of the connection is correct, A corresponds to A phase, B corresponds to B phase, and C corresponds to C phase.
Step 4. After changing the wiring method, it is essential to go to the configuration menu of the meter. Here, you need to adjust the settings to the new wiring method from 3P4W to 3P3W.(Default 3P4W，Optional: 3P3W3CT and 3P3W2CT)
This step ensures that the meter accurately measures and monitors the electrical parameters in the new configuration. Additionally, verify that all settings related to voltage, current, power factor, and other relevant parameters are correctly configured to align with the updated wiring configuration.
Changing the wiring method from 3P4W to 3P3W is a professional way to deal with current imbalance. By removing the naught line, the system is more adaptable to situations where the current is relatively balanced, improving the accuracy of meter measurements.
