PD668I-AK1 Short version of single-phase digital ammeter (Black/White)

Overview

1. Purpose

This series of digital display instruments is a new generation of programmable intelligent dedicated digital display instruments, mainly used for measuring and indicating analog electrical parameter signals in electrical circuits, and can be extended to RS 485 interfaces or analog transmission output interfaces for remote transmission of measured electrical parameter data. Has a wide measurement range

High measurement accuracy, good stability, long-term operation without calibration, and the ability to set parameters on-site through panel buttons are ideal replacement products for original pointer instruments or ordinary digital instruments.

2. Technical features

This series of instruments adopts large-scale integrated circuits and high-performance single-chip microprocessors, and is designed in a modular manner using digital signal processing technology and SMT technology. It is equipped with switch output (upper and lower limit alarm) modules, analog transmission output modules, and RS 485 digital communication modules for users to choose from. It is very convenient to set parameters such as transformer multiplier, upper and lower limit alarm values (or ranges) and alarm switching, communication address and communication baud rate, transmission output mode and transmission output range of the instrument through the instrument keyboard. The instruments are produced using software calibration, and the modular and universal design significantly improves the production efficiency of the instruments, making this series of instruments highly cost-effective.

Technical Specifications

1. Single phase measurement range

• 1.1 Single phase AC voltmeter

  Measurement range: AC 0-400V

  
  

• 1.2 Single phase AC ammeter

  Measurement range: AC 0-5A

  
  

• 1.3 Sensor specific table (voltage)

  Measurement range: 0-9999V

  
  

• 1.4 Sensor specific meter (current) measurement range: 0-9999A

  
  

• 1.5 Sensor specific meter (frequency) measurement range: 0-9999Hz

2. Three phase measurement range

• 2.1 Three phase AC voltmeter

  Measurement range: AC 0-400V

  
  

• 2.2 Three phase AC ammeter

  Measurement range: AC 0-5A

  
  

3. Accuracy: ± 0.5%

4. Overload capacity: Continuous 1 2 times

• Signal input: DC 0/4-20mA or DC 0-5/10V Signal input: DC 0/4-20mA or DC 0-5/10V Signal input: DC 0/4-20mA or DC 0-5/10V

  
  

5 . Display mode: Four digit LED digital tube effective value display

6. Display resolution: One last word at the end

7. Input power: current<0  5 VA， Voltage ＜ 1 VA

8. Power supply: AC/DC 85-265V or AC 220V ± 15%, 50/60Hz

9. Power supply power consumption:<3VA

10. Alarm output: upper and lower limit alarm, contact capacity AC 250V/1A, DC 30V/1A

11. Transmission output: DC 0/4-20mA or DC 0-5/10V

12. Communication interface: RS485 communication, using MODBUS-RTU communication protocol

13. Working environment: A non corrosive gas environment with a temperature of -10~50 ℃ and a humidity of ≤ 85% RH

Programming and usage

1. Panel description

2. Key Function Description

• OK key: In programming mode, enter the menu when selecting a menu item.

• Reduce key: In programming mode, when selecting a menu item, select up in the same level menu. When setting data, subtract 1 from the current digit

• Add key: In programming mode, when selecting a menu item, press down on the same level menu, and when setting data, increment the current digit by 1

• Menu key: In the measurement display state, press and hold this key for 3 seconds to enter programming mode. The instrument will prompt for the password (Pro 9). The initial password is 0001. After the password is correct, the table can be set.

3. Operation process

The instrument automatically enters the measurement mode after being powered on for about 2 seconds. Press the key for 3 seconds to enter programming mode. The following is the operation flowchart:

Explanation: The programming password is: Basic function password 0001 (full range di SP, decimal point display position Po In, 485 communication address Addr, baud rate setting b AUD); Alarm function password 0002 (low alarm value AL, high alarm value AH).

Menu parameter description

serial number	Parameter code	Set range	Instructions
one		0~9999	Enter programming mode password; The initial password is 0001
two		0~9999	Full range display value
three			Position of decimal point display
four		1~247	Instrument communication address range
five		1200; two thousand and four hundred 4800; nine thousand and six hundred	Select communication baud rate "bAud": 1200; 2400; 4800 or 9600
six			Lower limit alarm value
seven			Upper limit alarm value

4. Schematic diagram of three-phase menu structure (user can set the ratio of 200:5A current transformer as follows)

5. Schematic diagram of single-phase menu structure (the user can set the ratio using a 20:5A current transformer as follows)

Installation and wiring

1. Appearance and installation hole size

2. Installation method

According to the appearance of the instrument, select the corresponding installation hole size in the table above, open a hole on the installation plane, insert the instrument into the installation hole, place the two accessories into the installation slot of the housing, push them tightly by hand, and then fix them with installation screws

(Note: If there is any inconsistency with the wiring diagram on the instrument housing, please refer to the wiring diagram on the instrument housing.)

Three phase wiring diagram:

Single phase wiring diagram:

• Power supply: The working voltage range of the instrument is AC 176-264 V or AC/DC 85-265 V. To prevent damage to the instrument, it is recommended to install a 1A fuse on the live side when using AC power. In areas with poor power quality, it is recommended to install surge suppressors and fast pulse group suppressors in the power circuit.

  
  

• Electricity signal input (current input and voltage input): The current input is a three-phase AC current signal input terminal of A, B, C, where I * is the current input terminal; The voltage input is a three-phase AC voltage signal input terminal consisting of A, B, and C. Please ensure that the phase sequence and polarity of the input signal correspond one-to-one with the terminals when wiring. The input voltage should not exceed the rated input voltage of the product, otherwise PT should be considered, and a 1A fuse must be installed at the voltage input end; The input current should not exceed the rated input current of the product, otherwise external CT should be considered.

  
  

• RS 485 communication wiring

  The instrument provides an RS 485 communication interface, using the MODBUS-RTU communication protocol (see appendix). Up to 32 instruments can be connected simultaneously on a communication line, and each instrument should have a unique communication address within the line. The communication connection should use shielded twisted pair cables with copper mesh, and the wire diameter should not be less than 0 5 mm. When wiring, the communication line should be kept away from strong electrical cables or other strong electric field environments. Users can choose other suitable connection methods according to specific situations.

MOBUS-RTU communication protocol

1. The instrument provides RS485 communication interface and adopts MODBUS-RTU communication protocol

2. Communication information transmission process

When a communication command is sent from the host to the slave, the slave that matches the address code sent by the host receives the communication command. If the CRC check is correct, the corresponding operation is performed, and then the execution result (data) is returned to the host. The returned information includes address code, function code, executed data, and CRC check code. If the CRC check is incorrect, no information will be returned.

• address code

  The address code is the first byte of each communication information frame, ranging from 1 to 247. Each slave must have a unique address code, and only the slave that matches the address code sent by the host can respond and send information. When sending information from the device, the data is sent starting with their respective address codes. The address code sent by the host indicates the address of the slave to be sent, while the address code returned by the slave indicates the address of the slave to be sent. The corresponding address code indicates where the information comes from.

  
  

• function code

  The second byte of each communication information frame. The host sends a function code to tell the slave what action should be performed. The slave responds with the same function code as the one sent from the host, indicating that the slave has responded to the host and performed the relevant operations.

  The instrument supports the following function codes:

  function code	definition	operation
  03H	Read register	Obtain the current binary value of one or more registers

  
  

• data

  The data area varies depending on the function code. These data can be numerical values, reference addresses, etc. For different slaves, the address and data information are not the same (a communication information table should be provided).

  The host can read and modify instrument data registers freely using communication commands (function code 03H), and the length of data read at once should not exceed the valid range of data register addresses.

  
  

The process of generating a CRC is as follows:

• Pre set a 16 bit register (hexadecimal, all 1s), called the CRC register;

• XOR the first byte of the data frame with the low byte in the CRC register, and store the result in the CRC register.

• Move the CRC register to the right by one bit, fill the highest bit with 0, move the lowest bit out and check.

• If the one removed in the previous step is 0, repeat the third step (next time): 1; XOR the CRC register with a preset fixed value (0A001H);

• Repeat steps three and four until 8 shifts are made, thus completing a complete 8-bit process;

• Repeat steps two to five to process the next eight bits until all byte processing is complete;

• The final value of the CRC register is the value of the CRC

4. Example of communication message:

Read Data (Function Code: 03H): This function allows users to obtain data collected and recorded by terminal devices, as well as system parameters. There is no limit to the number of data collected by the host in a single request, but it cannot exceed the defined address range. The following example is reading 1 data I from a slave with terminal device address 01H (2 words per address in the data frame).

Read data register (function code 03H): ReadThe current value is 5.000A, and the instrument address is 1.

• Inquiry data frame (host)

  address	command	Starting register address (high-order)	Starting register address (low bit)	Number of registers (high bits)	Number of registers (low order)	CRC16 (low position)	CRC16 (high position)
  01H	03H	00H	00H	00H	01H	84H	0AH

  
  

• Response data frame (host)

  address	command	data length	Data (6 bytes)	CRC16 (low position)	CRC16 (high position)
  01H	03H	02H	13H,88H	B5H	12H

  
  

5. MODBUS Address Information Table

• Three phase digital voltmeter

  address	Project Description	data type	attribute	Instructions
  0	A-phase voltage value	int	R	Secondary side value
  one	B-phase voltage value	int	R	Secondary side value
  two	C-phase voltage value	int	R	Secondary side value
  three	Pt voltage multiplier	int	R/W	1~9999

  
  

• Three phase digital ammeter

  address	Project Description	data type	attribute	Instructions
  0	Phase A current value	int	R	Secondary side value
  one	B-phase current value	int	R	Secondary side value
  two	C-phase current value	int	R	Secondary side value
  three	Ct current rate	int	R/W	1~9999

  Explanation: The voltage and current values read are the values on the secondary side

  Actual voltage value once=(voltage readout value xPT)/10V

  If the voltage value is read as 1000, PT=100, The current actual voltage value is 10000V=10.00KV

  Actual current value=(current reading value xCT)/1000A

  If the current value is read as 5000, CT=20, The current actual current value is 100.0A