Connection Area – Current Transformers
The differences between the SC-23 and KR-63 are illustrated here.
The SC-23 has provisions to connect to three current transformers. These correspond to the P1, P2 and P3 inputs in the voltage supply connection respectively. Figure below is an example of the SC-23 current transformer connection area.
The positive and negative (or neutral) connection terminals each correspond to a specific voltage reference frame. Refer to table below:
The KR-63 has provisions to connect to 6 different current transformers. These CTs are paired and correspond to the voltage reference frames as described in the table below.
Connecting the CTs
- PRO-TIP: Before running the CT wire through the mounting board, use a permanent marker OR marker labels to mark both ends of the white CT cables to denote CT numbers 1-6 (where appropriate). This will come in handy later when feeding the cables through the backboard and into the enclosure.
- When installing CTs, it is important to match CT and voltage reference frames. Be sure to consistently identify all the phases as you wire in and clip on the CTs. Existing wire colours may not always be consistent in identifying the A, B and C phase. If in doubt, use a multi-meter to check.
- Feed all the CT tails through to the mounting point. Wire in the CT tails to the phoenix plug provided as per the Wiring Diagram. See Figure 8 below for an example of a completed CTs phoenix plug for the SC-23 and KR-63 respectively.
- Clip the CTs around the cables intended for measurement. Take extra care to ensure you have a clear order in which you clip the CTs. For single phase solar on 3 phase consumption using the KR-63, the typical CT allocation is as follows:
*This CT needs to match the phase that the Solar PV system is installed on. In the set up above, the Solar PV system is installed on the Phase A.
- Please ensure the CTs are closed tight and the K → L is facing the right way. Please refer to the Wiring Diagram or the correct CT orientation.
- Making note of the CT allocation is crucial for the registration and commissioning process.