1. Why there is no display signal after the meter is electrified?
The auxiliary power supply is not connected.
a. Take a multimeter to check if there is enough working voltage on the terminals (1 and 2) of auxiliary power supply.
b. Check the terminal connections of auxiliary power supply.
2. What should I do if the meter flashes abnormally after power supply is connected?
The supply voltage is out of normal working range.
a. Disconnect the auxiliary power supply.
b. Check if the auxiliary power supply exceeds the range on the meter.
c. Check whether the input signal is over 120% of rated value.
d. Make sure that the ambient temperature is not beyond the approved limit.
e. Reconnect the auxiliary power supply.
3. Why the meter only displays garbled text after electrified?
The meter suffers interference seriously.
Disconnect the auxiliary power supply and then re-connect it.
4. Why the revealed data are not precise?
a. The transformation ratio is not proper.
b. The parameters are not matched.
a. Verify if the transformation ratio set in the meter is in accordance with corresponding values in PT or CT.
b. Check if the rated values of voltage and current are accordant.
5. What happens if the meter doesn't response to signal?
Perhaps the signal is not transferred to the meter.
a. Make sure there is signal between wiring terminals.
b. Check if the terminal connection is reliable.
6. Why there is phase loss for a three-phase meter?
a. The signal is not transmitted to the meter.
b. The settings are not matched.
a. Test the wiring terminals to see if there is signal and if the connection is correct.
b. Connect a normal working wire to the meter to replace the phase-losing wire to figure out whether the problem roots in meter or external circuit.
c. Confirm the compliance between practical wring mode and wring mode of meter.
7. It seems that the electricity calculation is not accurate, why?
a. The transformation ratio is wrong.
b. There is a problem with the phase sequence of current or voltage.
a. Check if the transformation ratio of meter matches with PT or CT.
b. Ensure the correct phase sequence of voltage or current.
c. For a meter with power measuring function, use this function to see if there is negative sign for the single-phase power after electrified. The negative sign possibly denotes that the in and out wires of corresponding phase are reversed.
8. Is there any suggestion when the analog output is not accurate?
Maybe the measuring range or item correspondence of analog output is not correct.
a. Confirm the correspondence of upper and lower measuring range of analog output.
b. Ensure the validity of relevant electrical parameters, such as U, I, P, Q, etc.
c. The testing equipment is in normal condition.
d. If PLC is applied, detect the PLC analog input wire.
9. What are recommended measures if abnormal communication occurs?
Generally speaking, there are 3 types of abnormal communication, and the solutions vary from each other.
The first type is that the meter doesn't send back data. When this phenomenon happens, please make sure that the communication settings of meter meet the requirements of host, and the items include slave address, baud rate, check mode, and others. If this problem occurs for more than one meter, please check if the connection of communication bus is still reliable and if the RS485 converter is OK. Under the condition that only a few meters are abnormal, corresponding communication wires need to be detected as well, and there are two recommended methods. The first one is to change the slave addresses of regular and irregular meters, and you can determine if there is a problem with the software of host machine. The second one is to change the installation positions of these meters to see if the problem lies in meter.
The second type is that the meter sends back data, but the data is not correct. As we know, the communication data has two categories, primary data (float type) and secondary data (int/long type). Our customer should read the descriptions about data storing address and format carefully, and the data converting format needs to be confirmed. ModScan32 software meets standard Modbus-RTU protocol, and it can be used to detect the communication. Data derived from the test are revealed in integer, floating point, hexadecimal number or other forms, and you can make a direct comparison between these data and meter-displayed data.
The last type is state information of communication indication signal. During communication test, the communication indication signal will flash if the meter collects data.
10. After electricity is connected, the running indication light of motor protection controller is constantly on, but the display module is still abnormal. What is the reason?
a. DB9 connecting line is used to connect the main body and the display module, maybe it is in bad contact status.
b. DB9 line is broken after bending.
a. Cut off electricity, and tighten the DB9 connecting line.
b. Replace the DB9 line if it is broken.
11. When there is no load for test control loop, the contactor doesn't act as it is supposed to be. What is wrong?
Suppose that the debugging control loss has no load, when the controller receives start command from buttons of display module or from DI terminal, the contactor is electrified and closed for 2 seconds, then it is released, indicating that it can maintain closing state. At the same time, the display module will show progress bar of "start" for only 2 seconds, are returns to "ready to start" page. Additionally, the relay may act abnormally, too.
For all the other control modes except protection mode, the controller checks if the starting process is normal by detecting the main-loop current. After the start command is received, the main relay, which is responsible for the contactor loop, is closed, and the contactor will be electrified and closed. 2 seconds later, if the main-loop current is not over 10% of the rated current, it draws a conclusion that the motor is not started, and the relay will be switched off, resulting in the release of contactor.
a. Under no-load debugging test, enter the parameter setting interface, press "controller parameter setting" - "run mode", and modify "run" to "test". After this operation, the controller won't monitor main-loop current, and all the protection functions are disabled, but the control logic still works normally. Under this condition, the control loop without load can be detected. After debugging, please set the "test" back to "run".
b. An alternative solution is to carry out calibration with load.
12. The motor starts and stops normally, but the measured data are inappropriate. The motor protection controller may mis-respond or not act at all. What is the problem?
There is "run data" in the display module, but it reads wrong. For example, the three phases of current are all 0%, or one phase of current is 0% while the other two are correct, or three phases of current are not 0%, but vary from actual current greatly. Also, there may be a problem with power or power factor, though the voltage and current are correct.
a. The controller's transformer has a plug, and maybe there is something wrong with the connection between the plug and controller body.
b. The rated current of motor or the transformation ratio of CT is not properly set.
c. The current of controller is not matching with motor circuit.
d. The phase sequence of voltage or current is mis-connected.
a. Detect the connection between transformer and controller.
b. Properly set the rated current of motor as well as transformation ratio of CT if external transformer is applied.
c. Check the phase sequence of voltage and current.