MH-ACJK3 monitoring device is a low power consumption, fully intelligent AC combiner box monitoring unit host developed by our company, which is specially used for AC photovoltaic combiner box. Real-time monitoring of three-phase voltage, three-phase current after merging, total circuit breaker status and lightning arrester status, and circuit breaker status of each of the branches The current is monitored. With isolated RS485 interface, it can upload the monitored data and switch value.
2. Features ● Small size and easy installation ● The monitoring device directly uses the AC power supply in the box as the working power supply ● Three-phase AC phase voltage and line voltage measurement, and external current transformers can perform current measurement after three-phase confluence ● Can provide active power AC parameters such as power, reactive power, power factor, frequency, etc. ● One channel temperature measurement, which can measure the temperature inside the box ● 12 digital inputs, which can monitor the operating status of the lightning arrester, main switch and 10 branch switches respectively ● Remaining branch current monitoring module interface ● Isolated RS485 interface for remote data communication, supports MODBUS-RTU protocol ● RS485 interface comes with signal lightning protection function
Third, the technical parameters
Rated voltage input
AC 3 × 220V (380V)
AC 3 × 480V
AC 3 × 690V
Self-powered, phase A and C phase line voltage
Working power voltage range
- AC 90 ～ 560V (rated voltage 380V, 480V)
- AC 400V ～ 800V (rated voltage 690V)
Voltage measurement range
0.5%-120% of rated voltage
Voltage measurement accuracy
Rated current input
(100 – 630A) / 1A
Current measurement range
0.5%-120% of rated current
Current measurement accuracy
-50 ℃ ～ 100 ℃
Passive dry contact input, normally open
Normal working temperature
-30 ℃ ～ 70 ℃
Extreme storage temperature
-40 ℃ ～ 85 ℃
Normal working humidity
5% ～ 95% non-condensing
Safety isolation voltage
Between voltage input and secondary main control circuit: 2500VAC 60 seconds Between voltage input and case ground: 2500VAC 60 seconds between data upload interface and secondary main control circuit: 1500VAC 60 seconds
Data upload interface
Standard RS-485 interface factory setting: Address: 1 Baud rate: 9600bps
Data format: 10 bits without parity (1,8,1.n)
Number of supported nodes: 128
Fourth, the external dimensions and terminal definition diagram
Dimensions: 115 × 90 × 40 (including terminal blocks)
Terminal definition table
| Terminal name |
Terminal group function
AC voltage input
Phase A phase line (AC line voltage provides working power)
Phase B phase line
Phase C line (AC line voltage provides working power)
Three-phase current transformer input
A-phase current transformer non-inverting terminal
A-phase current transformer reverse terminal
Phase B current transformer at the same phase
Phase B current transformer inverting terminal
C-phase current transformer at the same phase
C-phase current transformer reverse terminal
Data upload 485 interface
Connected to ground (earth)
12 digital inputs
For connecting lightning arresters and main circuit breakers
Switch output of each branch circuit breaker
Each switch is connected to the common terminal
Branch current monitoring module
Branch current monitoring module power
DI12 / T
Tributary current monitoring module serial communication interface
(And the 11th and 12th channel multiplexing)
DI11 / R
Five, the indicator description
There are three indicators on the monitoring device, the instructions are as follows:
1. RUN Green running indicator. The main unit is running normally when it is powered on. This indicator flashes.
2. TX yellow host data upload and send indicator. When the monitoring host receives the command correctly and sends data to the background, this light is on.
3. RX yellow As long as there is data transmission on the RS485 bus, this light will be on. You can judge the bus activity based on the flashing of the RX light.
Reference wiring diagram
Extension branch current monitoring module wiring diagram
Seven, alarm description
1. This device is designed with 7 alarm signs: over temperature alarm, three phase voltage over voltage alarm, and three phase over current alarm.
In order to facilitate the background program design, a register is used to designate an alarm flag design.
2. Three parameters of temperature upper limit, voltage upper limit, and current upper limit can be set (supporting handset or supporting tool software)
Eight, current transformer setting instructions
The transformer connected to this device is specified as a current transformer with a rated 1A output. When setting, as long as the input of the transformer is set
Rated current, such as a 400 / 1A transformer, as long as the current transformer parameter is set to 400A (use the supporting handset or supporting tool software settings).
Nine, MODBUS-RTU communication protocol description
1. The serial communication of this device fully complies with the standard MODBUS-RTU protocol. The data format, hardware timing and data frame structure fully comply with the MODBUS protocol. 8,1, n), as long as the address of the monitoring device is set using our special tool software, fast and error-free communication can be performed.
2. This device supports the functional field codes in the MODBUS protocol:
| function code |
Read measurement data, read all setting parameters
Set communication address, rated current specifications, etc.
3. Detailed function code
Function code 03H: read register, read measurement data and parameters
Data definition: See Annex 1 Register data comparison table
Example 1. Read phase A current data:
Command (binary): 01 03 01 02 00 01 CRC 8 bytes
Address function code start address register number CRC check
Response (binary): 01 03 02 01 80 CRC 7 bytes
Address Function Code Bytes Current Data CRC Check
Read phase A current data: 38.4A (384/10)
Function code 10H: write register
Data definition: See the register data comparison table in Annex 1.
Example 2: Write the transformer parameters (change the rated current of the current transformer to 400A)
Command: 01 10 0042 0001 02 0190 CRC
Address function code start address register number of bytes 400A CRC check
Response: 01 10 0042 0001 CRC
Address function code start address register number CRC check
Ten, precautions for use
1. Make sure that the working power supply is within the specified range.
2. Make sure that the communication interface is connected to a standard RS485 network. It is recommended to use a shielded twisted-pair cable of 120 ohms for external RS485 network cables.
3. The ground terminal on the monitoring device is a lightning overvoltage bleeder terminal. Please be sure to connect it during installation.
4. The use environment should be free of conductive dust and non-corrosive metals and gases that damage insulation.
5. Non-professionals should not disassemble this product.
6. If the RS485 network cable of the connected device has an outdoor part, please do lightning protection treatment of the network cable.