Can’t increase the current in the rectifier cabinet? Waiting online, thanks for the analysis
Thread Content
The electrolyzer is equipped with a thyristor rectifier cabinet of model KHS-1000A/90V. At present, it is not possible to increase the current; replacing the capacitor and thyristors has not resolved the issue. We request the manufacturer to analyze and address this problem – waiting urgently
The thyristor has been replaced, so it must be a problem with the control trigger. Use an oscilloscope to check whether the trigger signal is normal Otherwise, it’s a load issue!
If the current cannot be increased, it can be analyzed in two scenarios: if the voltage can be increased, then it is definitely a problem with the load; carefully check the connections such as the busbars and slots, as well as their performance； If the voltage cannot be increased either, there must be a problem with the triggering.
The on-load voltage regulation levels can also be adjusted to correspond to changes in current.
The capacity of this rectifier unit is limited, so the current cannot be increased. First, check whether the power supply is functioning properly, as well as issues such as missing phases, voltage levels, and balance； Furthermore, a light-load test can be conducted by connecting an electric furnace to see if the voltage can be adjusted continuously. If there are no issues, then the problem lies with the load; if the voltage cannot be adjusted, first check the condition of the fast fuse, and then examine the trigger control circuit using an oscilloscope.
With all the peripheral devices working properly, increase the voltage by one level and apply a direct voltage surge two or three times to see if it works. If that doesn’t work, then with the device powered on (at the highest current level you can set), use the millivolt setting on a multimeter to measure the voltage across each of the 6 fast-blow fuses. If the voltage values are similar, then reinsert the 6 fuses in order ； If the voltage values differ significantly, then check the condition of the thyristor by measuring the resistance between the K and G terminals, as well as examining the solder joints and similar elements. That’s all I can know. I hope this will be helpful to you.
Reply to 2# liuei: Hello, I would like to ask about the frequent fluctuations in current in our rectifier cabinets. The current drops from its set value to zero and then rises back to its maximum value; after several such fluctuations, operation resumes normally. This phenomenon occurs quite often when the cabinets are running in automatic mode. When this fault occurs, switching to manual mode for adjustment doesn’t work; there is no current output, but it returns to normal after a while. What could be causing this issue? Thank you. I’m sorry to bother you
First, rule out any issues with the load
It won’t increase; check whether the current sensor is working properly. It’s either a feedback issue. Check the current feedback circuit.
Find out whether it is current negative feedback; temporarily disconnect the feedback and see if there is any change in the current. Determine how many sets of thyristors there are by checking their forward and reverse resistance values. The trigger waveform can be seen using an oscilloscope; by checking whether the trigger voltage is normal, it’s possible to determine the issue fairly accurately
Based on the phenomenon you described, it might be a problem with the synchronization signal