Determination and elimination of the operation fault of potentiostat

Determination and elimination of the operation fault of potentiostat

Fault, potentiometer, elimination, judgment, operation

Determination and elimination of the operation fault of potentiostat

The previous is the principle of the use of the potentioscope, now talk about the potentioscope - cathodic protection in the operation of some of the faults and treatment, for the reference and discussion of users.

The potentiostat is a mature instrument, the circuit structure is not complex, the quality of the instrument is rarely the circuit fault. In the cathodic protection system composed of pipes, some common faults occur, the main phenomenon is the output disappears or out of control. Generally, the control potential and protection potential indicated by millivoltmeter are used as the basis for judging whether the potentiostatic is working normally. Of course, the increase and decrease of potential are also errors, and the error is also increased and decreased, but the difference is known when combined with the actual use: the first two are the increase and decrease under the condition of loss of insurance, and the last one is the increase and decrease under the condition of protection.

To deal with the fault of potentiostat, we should make full use of the switch meter of the instrument, combined with different position conditions, first determine whether the fault occurs outside or inside the instrument, and then targeted elimination. The switch meter that can help determine the fault is mainly: "Control - protection" (some instrument is "a given reference") switch, the output voltage table, the table output current, "instructions" table (some instruments are electronic "millivoltmeter", some instruments have been adopting digital display), according to the "control - protection" switch the location of the potential indicator of different circumstances, with or without the size of the output voltage and current, The fault (strictly speaking, the fault of the cathodic protection system) that compresses most of the potentiostatic operation can be determined.

1.

The control potential is normal, the protection potential is high or full amplitude, and the output voltage and current are zero. This phenomenon is an external fault, which may be the reference electrode cable or zero connection cable disconnect, or the reference electrode damage, failure or flow empty. It can be checked and eliminated by several times.

2.

Control voltage is normal, protective potential is low, close to the natural potential, output current is zero, the output voltage high or full picture, this kind of phenomenon is external fault, the most likely is the cathode or anode breakout cable, may be less terminals, virtual or galvanostatic point loss, less likely to have anodic rust off (to run pipe could be relatively increase) for many years, before the targeted check the above aspects, Make sure the potentiostat output safer is in good condition. (The output insurance burn out, strictly should be classified as internal fault, but it is the first output loop, for the simple and clear attribution to the broken line class outside.)

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3.

Normal control voltage, protection potential deviation control, the error is large, the output voltage current normal (along with the changes of control), this phenomenon is commonly the potentiostat fault, comparing amplifier circuit balance disorders, checking and adjusting recoverable, more adjustment cannot restore has bad components, check out after adjust circuit; Rarely is an external fault caused by poor reference electrode characteristics and replacement.

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4.

The control potential is normal or abnormal (abnormal performance is not synchronized with the regulation), the protection potential is low, close to the natural potential, the output voltage and current are zero, this phenomenon can determine the internal fault of the potentiostat, the circuit components, components, and the circuit related to the terminal, plug-in, dropped line and so on to check and eliminate.

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5.

Check and troubleshoot the internal circuit faults of the potentiostat. Master the circuit composition and principle of the potentiostat, and have necessary tools and instruments and spare parts of the standby board. Check the potentiostat circuit fault, should be in line with from the back to the front, from simple to complex principle, step by step, level by level check exclude, specifically, check the polarization power supply, to determine the normal -- check the trigger circuit -- check the oscillation circuit, phase shift circuit (pulse formation) -- check the output, amplification and so on; Check the circuit fault method, the commonly used test method: by detecting the key point voltage or the key path current, and grasp the normal value to judge the fault; Comparison method: the measured value is compared with the normal state circuit to judge and find the fault; Replacement method: to determine good components, replace suspicious components, judge and find faults; Various methods in the inspection and troubleshooting should be flexible, appropriate combination of use, it is not difficult to find out, troubleshooting.

6.

When conditions are available, the potentiostat can be equipped with oscilloscope. By observing the waveform, it can help to find out and determine the fault more quickly and accurately.

The inserted flow chart is designed for a single fault. Sometimes, though not much - failures are combined, which is simultaneously in two or more parts of the fault, the principle of checking out the same way, but need to find out a troubleshooting, check out the second and the third failure, then to increase in front of a "from outside to inside," to do the general principles: "From outside to inside, from back to front, from simple to complex." That is, first check and eliminate the external wiring and facility faults, and then check and eliminate the internal faults of the potentiostat, among which "complex", bias refers to check and eliminate the fault of the circuit part. But grasp of the good, accumulated more maintenance experience, "complex" can also not complex, the same to achieve the disease, solved!