DTSU666-CT
The Chint DTSU666-CT is the three-phase smart meter with current transformers (CT) for photovoltaic systems with Solax three-phase inverters. It measures bidirectionally up to 200 A, with RS485 Modbus RTU communication. Ideal for high-current commercial installations where direct insertion is not possible. CT set included in the supply.
The Chint DTSU666-CT is the smart three-phase energy meter with external current transformers (CT), designed for photovoltaic systems with Solax three-phase inverters operating on networks with high currents. Thanks to indirect measurement via CT, it is suitable for systems up to 200 A, covering medium-high power commercial and industrial installations.
DTSU666-CT vs DTSU666-D: which one to choose?
The DTSU666 family includes two variants. The DTSU666-D is a direct insertion model (up to 80 A) and does not require external CTs; the DTSU666-CT uses external current transformers and covers systems up to 200 A. The CT version is the correct choice whenever the network current exceeds 80 A or the AC cable has a large cross-section, typically in commercial three-phase or multi-inverter systems. The function is identical for both: bidirectional measurement and RS485 Modbus RTU communication with the Solax inverter.
DTSU666-CT Technical Specifications
| Model | DTSU666-CT (Chint / Solax) |
| Network type | Three-phase 3P+N |
| Nominal voltage | 3×230/400 Vac |
| Maximum system current | 200 A (with external CTs) |
| Frequency | 50–60 Hz |
| Accuracy | Class 1 |
| Communication protocol | RS485, Modbus RTU |
| RS485 port | Ports 24 and 25 of the meter |
| CT cable cross-section | ≥ 5 AWG or 16 mm² |
| Communication cable cross-section | 17–23 AWG or 0.25–1 mm² |
| Self-consumption | ≤ 1 W |
| Display | LCD |
| Installation | Indoor (wall or panel) |
| Inverter compatibility | Solax X3-Hybrid G4, X3-MIC, X3-PRO (three-phase) |
When should you choose the DTSU666-CT?
Choose the DTSU666-CT when the three-phase system exceeds 80 A or when the AC connection cable has a large cross-section that does not allow direct insertion. It is the standard solution for commercial and industrial systems with Solax three-phase inverters. The CTs are installed on the three phases at the point of connection to the grid, without interrupting the circuit during installation.
What is included in the supply?
- DTSU666-CT meter
- Set of 3 current transformers (CT) for three-phase measurement
- RS485 communication cable for connection to the Solax inverter
Frequently Asked Questions
What is the difference between DTSU666-D and DTSU666-CT?
The DTSU666-D is a direct insertion model (max 80 A, no external CT), while the DTSU666-CT uses external current transformers and supports systems up to 200 A. Both provide bidirectional measurement and communicate with the Solax inverter via RS485 Modbus RTU. The choice depends on the maximum system current and the AC cable cross-section.
Are the current transformers (CT) included with the DTSU666-CT?
Yes, the DTSU666-CT comes complete with a set of 3 current transformers for three-phase measurement. The CTs are installed on the three phases of the incoming line from the grid, at the connection point, allowing measurement without interrupting the main circuit.
Does the DTSU666-CT enable zero export to the grid even on three-phase systems?
Yes. Once connected via RS485 to the Solax three-phase inverter and the Export Control function is configured from the inverter menu, the DTSU666-CT allows you to set the export limit to any value, including 0 W for full zero export to the grid. The functionality is identical to the single-phase DDSU666-D version, applied to a three-phase network.
How do you connect the DTSU666-CT CTs to the phases?
The current transformers are installed on the three phases L1, L2, L3 at the point of connection to the grid (upstream of the main panel). The CT cables are connected to the CT input ports of the meter (CT cable cross-section ≥ 5 AWG or 16 mm²). The L phases then enter the voltage acquisition terminals of the meter (ports 2/5/8) and the neutral into port 10. Only qualified electrical personnel should perform the installation.
Can I use the DTSU666-CT with non-Solax three-phase inverters?
The DTSU666-CT is optimized for Solax three-phase inverters and is the model officially recommended by Solax Power for high current systems. Compatibility with inverters from other manufacturers that support the Modbus RS485 protocol is technically possible but not guaranteed. For other brands, always check protocol compatibility with your inverter.
